HVAC Instrumentation and Control Devices
Remade from scratch under the authoring cheatsheet: the field-device layer of the building automation system, control valves and pneumatic devices owned here, one enclosure field with the harsher locations as clauses, a trade-off note beside every choice
Showing changes from Rev 2
to Rev 3
in HVAC Instrumentation and Control Devices.
---
title: HVAC Instrumentation and Control Devices
category: Mechanical / Controls & Testing
−toc_depth: 3
description: >
− When to use: Specifying the field layer of HVAC control devices for commercial,
− institutional, and light-industrial buildings (new construction or major renovation):
− space, duct, immersion, and outdoor temperature/humidity sensors; differential-pressure
− transmitters for duct static, hydronic, and filter applications; CO2 sensors for
− demand-controlled ventilation; occupancy sensors in the HVAC loop; airflow measurement
− stations; unitary/terminal thermostats; and electric valve and damper actuators furnished
− under the controls scope. Covers device selection, accuracy, enclosure, mounting,
− termination, and field calibration/verification for devices wired to BAS field
− controllers over hardwired, BACnet MS/TP, BACnet/IP, or Modbus RTU networks.
− Not intended for: BAS controllers, network architecture, programming, and sequences of
− operation (use [[sync/building-automation-system]]); testing, adjusting, and balancing
− (use [[sync/testing-adjusting-and-balancing]]); functional performance testing and
− commissioning (use [[sync/commissioning]]); industrial process control valves and
− positioners (use [[sync/control-valves-and-actuators]]); industrial process
− instrumentation and flow measurement (use [[sync/process-instrumentation]] and
− [[sync/flow-measurement]]); the damper, louver, and damper-body assemblies the actuator
− mounts on (use [[sync/louvers-and-dampers]]); ductwork and hydronic piping (use
− [[sync/hvac-ductwork]] and [[sync/hydronic-piping]]); control wiring conductors and
− raceways (use [[sync/conductors-and-cables]] and [[sync/raceways-and-conduit]]); VFD
− speed-reference points (use [[sync/hvac-variable-frequency-drives]]); lighting-only
− occupancy sensors (use [[sync/lighting-controls]]); and fire alarm duct smoke detectors
− (use [[sync/fire-alarm-systems]]).
+ When to use: The field-device layer of a building automation system: the sensors, transmitters, switches, thermostats, and actuators wired or networked to the field controllers that execute HVAC sequences of operation. Covers space sensors and thermostats; temperature sensor assemblies with probes, averaging elements, thermowells, and radiation shields; humidity, carbon dioxide, and indoor air quality sensors; pressure transmitters and switches; equipment status, flow-proving, low-temperature, and condensate overflow switches; occupancy signal sources for HVAC; airflow measurement station hardware; water leak detectors and interposing relays; automatic control valves for hydronic and steam coils; electric damper and valve actuators; and pneumatic control devices where a pneumatic system is retained. Addresses supply and signal interface, wireless sensor policy, enclosure ratings by location, device-level acceptance testing, and spares, for new construction, whole-system replacement, and expansion of an existing control system.
+
+ Not intended for: The controllers, network, programming, graphics, alarming, trending, and cybersecurity of the building automation system, and the system-level device selections it owns, namely sensing element type, measurement error, carbon dioxide range and background calibration, pressure and airflow ranges, actuator control signal, fail-safe mechanism, torque margin, and close-off basis (see [[sync/building-automation-system]]); process instrumentation and control valves for industrial and water facilities (see [[sync/process-instrumentation]] and [[sync/control-valves-and-actuators]]); pressure-independent control valves furnished as a hydronic specialty complete with their actuator (see [[sync/hydronic-specialties]]); the compressor, dryer, and main distribution of a control air system (see [[sync/compressed-air-systems]]); damper bodies and life-safety dampers with their listed actuators (see [[sync/louvers-and-dampers]] and [[sync/fire-and-smoke-dampers]]); duct smoke detectors (see [[sync/fire-alarm-systems]]); refrigerant and combustion gas detection (see [[sync/gas-detection-systems]]); occupancy sensors serving only lighting (see [[sync/lighting-controls]]); variable frequency drives (see [[sync/hvac-variable-frequency-drives]]); testing, adjusting, and balancing (see [[sync/testing-adjusting-and-balancing]]); and control conductors and raceways (see [[sync/conductors-and-cables]] and [[sync/raceways-and-conduit]]).
---
# Scope {toc}
−## This standard governs the field layer of the HVAC controls system: the sensing elements, transmitters, thermostats, and actuators that gather signals for and execute commands from the building automation system. {note}
+## This standard covers the field devices of the building automation system: the instruments that measure a condition, the switches that prove a state, the thermostats that control unitary equipment, the control valves that vary coil and heat exchanger flow, and the actuators that move dampers and valves. It begins at the field controller's terminal strip and extends outward to the point of measurement or actuation. {note}
−## It begins at the field controller's terminal strip and extends outward to the point of measurement or actuation. Everything from the controller inward — the controller itself, the network, programming, and the written sequences of operation — belongs to [[sync/building-automation-system]]. Drawing the boundary at the controller terminal keeps two different trades and two different submittal reviews from overlapping at the most error-prone seam in a controls installation. {note}
+## The building automation system standard owns the system-level decisions about these devices, and this standard does not restate them. The following are selected under [[sync/building-automation-system]] and apply to every device furnished here. {note}
−## The devices covered are the physical instruments a technician can touch, calibrate, and replace. {note}
+- The temperature sensing element, the maximum combined measurement error for temperature, humidity, carbon dioxide, pressure, and airflow, and the sensor operating band within the sensor range
+- Carbon dioxide measurement technology, range, and the automatic background calibration policy
+- Duct static and hydronic pressure sensor ranges, and the airflow measurement technology
+- The modulating control signal, the fail-safe mechanism for each damper and valve class, the damper actuator torque margin, and the valve close-off basis
+- Control wiring practices, the labeling method, point naming, calibration reference traceability, and the field functional testing scope
−## This includes space temperature sensors and wall thermostats; duct, mixed-air, immersion, and outdoor temperature and humidity sensors; differential-pressure transmitters for duct static, hydronic, and filter applications; CO2 sensors for demand-controlled ventilation; occupancy sensors tied into the HVAC loop; airflow measurement stations; and electric valve and damper actuators furnished under the controls scope. {note}
+## What remains for this standard is the device itself: its housing and occupant interface, its probe, well, shield, or manifold, its supply and output, whether it is wired or wireless, the switches that report status and protect equipment, the interposing relays between controller and equipment, the control valve body and its sizing, the actuator hardware features, the pneumatic devices and control air of a retained pneumatic system, the enclosure rating for its location, and the device-level tests that prove each one before the system is functionally tested. {note}
−## Devices shall be furnished, installed, terminated, field-calibrated, and point-to-point verified under this section prior to testing, adjusting, and balancing.
+## The following are outside this standard and are governed elsewhere. {note}
−## Devices shall be compatible with the building automation system controllers and network protocols specified in [[sync/building-automation-system]].
+- Sequences of operation, which are published on the contract drawings and in the equipment standards
+- Pressure-independent control valves furnished as a hydronic specialty complete with their actuator, governed by [[sync/hydronic-specialties]]
+- The compressor, dryer, receiver, and main distribution that produce and deliver control air, governed by [[sync/compressed-air-systems]]
+- Damper frames, blades, seals, and leakage class, governed by [[sync/louvers-and-dampers]], and fire, smoke, and combination dampers together with their listed actuators, governed by [[sync/fire-and-smoke-dampers]]
+- Duct smoke detectors, governed by [[sync/fire-alarm-systems]]
+- Refrigerant, carbon monoxide, and combustible gas detection, governed by [[sync/gas-detection-systems]]
+- Process-grade pressure, level, and temperature instruments, governed by [[sync/process-instrumentation]], and modulating process control valves, governed by [[sync/control-valves-and-actuators]]
+- Instrument-grade airflow and water-flow measurement performed by the balancing agency, governed by [[sync/testing-adjusting-and-balancing]]
+- Control conductors, cable, and raceway, governed by [[sync/conductors-and-cables]] and [[sync/raceways-and-conduit]]
−## Each device shall be selected to satisfy the sensor inputs and actuator outputs required by the project's sequences of operation.
+## Field devices shall be furnished, installed, and tested by the controls contractor responsible for the building automation system under [[sync/building-automation-system]].
−## ASHRAE Guideline 36 is the best single reference for determining which inputs and outputs a given system type requires; the sequences themselves are owned by the BAS standard, but the device list must satisfy them. {note}
+## The devices furnished shall provide every hardware input and output required by [[drawing: the points list]].
−## The following work is explicitly excluded from this standard and is governed elsewhere. {note}
+## Device locations shall be as indicated on [[drawing: the controls drawings]].
−## The boundaries below are stated as scope exclusions, not obligations, because no one performs them under this section. {note}
−- BAS controllers, network architecture, operator workstations, programming, sequences of operation, scheduling, alarming, trending, and cybersecurity — [[sync/building-automation-system]].
−- Testing, adjusting, and balancing, including instrument-calibrated airflow and water-flow measurement by a TAB agency — [[sync/testing-adjusting-and-balancing]].
−- Building commissioning and functional performance testing of integrated systems — [[sync/commissioning]].
−- Industrial and process modulating control valves and valve positioners — [[sync/control-valves-and-actuators]].
−- Process pressure, level, and temperature instrumentation with process-grade RTDs and thermowells — [[sync/process-instrumentation]].
−- Industrial and process flow measurement instruments — [[sync/flow-measurement]].
−- Louver and damper bodies, including volume-control, fire, and smoke dampers; only the actuator mounted on the body is covered here — [[sync/louvers-and-dampers]].
−- HVAC ductwork materials and construction — [[sync/hvac-ductwork]].
−- Hydronic piping materials and specialties — [[sync/hydronic-piping]].
−- Control conductors, signal cable, and control wire — [[sync/conductors-and-cables]].
−- Raceways and conduit methods for control wiring — [[sync/raceways-and-conduit]].
−- HVAC variable-frequency drives and their integral speed-reference points — [[sync/hvac-variable-frequency-drives]].
−- Lighting occupancy sensors used solely for lighting control — [[sync/lighting-controls]].
−- Fire alarm duct smoke detectors installed and tested under the fire alarm contract — [[sync/fire-alarm-systems]].
+## Where a device required by the points list is not located on the controls drawings, the Contractor shall request its location from the Engineer in writing before roughing in the wiring that serves it.
# Referenced Standards {toc}
## Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
−## Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+## Where the contract documents, the adopted building code, or a referenced standard conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
| Standard | Title |
|----------|-------|
−| ANSI/ASHRAE 135-2024 | BACnet — A Data Communication Protocol for Building Automation and Control Networks |
−| ANSI/ASHRAE/IES 90.1-2022 | Energy Standard for Buildings Except Low-Rise Residential Buildings |
−| ANSI/ASHRAE 62.1-2022 | Ventilation and Acceptable Indoor Air Quality |
−| ASHRAE Guideline 13-2015 | Specifying Direct Digital Control Systems |
−| ASHRAE Guideline 36-2021 | High-Performance Sequences of Operation for HVAC Systems |
−| NFPA 70 | National Electrical Code (Articles 725, 800, 430) |
−| NFPA 90A-2024 | Standard for the Installation of Air-Conditioning and Ventilating Systems |
+| ANSI/ASHRAE 135 | BACnet - A Data Communication Protocol for Building Automation and Control Networks |
+| ANSI/ASHRAE 62.1 | Ventilation and Acceptable Indoor Air Quality |
+| ANSI/ASHRAE/IES 90.1 | Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings |
+| ANSI/ASHRAE Guideline 13 | Specifying Building Automation Systems |
+| ANSI/ASHRAE Guideline 36 | High-Performance Sequences of Operation for HVAC Systems |
+| ANSI/ISA-5.1 | Instrumentation Symbols and Identification |
+| ANSI/ISA-7.0.01 | Quality Standard for Instrument Air |
+| ANSI/ISA-75.01.01 | Industrial-Process Control Valves: Flow Capacity, Sizing Equations for Fluid Flow Under Installed Conditions |
+| ANSI/FCI 70-2 | Control Valve Seat Leakage |
+| ASME B16.34 | Valves: Flanged, Threaded, and Welding End |
+| ASME B31.9 | Building Services Piping |
+| NFPA 70 | National Electrical Code (Article 725 - Class 2 and Class 3 circuits) |
+| NFPA 90A | Installation of Air-Conditioning and Ventilating Systems |
| UL 916 | Energy Management Equipment |
−| UL 60730-1 | Automatic Electrical Controls — General Requirements |
−| NEMA 250-2020 | Enclosures for Electrical Equipment (1000 V Maximum) |
−| IEC 60529 | Degrees of Protection Provided by Enclosures (IP Code) |
−| ISA-5.1-2009 | Instrumentation Symbols and Identification |
−| ANSI/ISA-51.1-1979 (R1993) | Process Instrumentation Terminology |
−| AMCA 500-D | Laboratory Methods of Testing Dampers for Rating |
+| UL 873 | Temperature-Indicating and -Regulating Equipment |
+| UL 353 | Limit Controls |
+| UL 508 | Industrial Control Equipment |
+| UL 60730-1 | Automatic Electrical Controls - General Requirements |
+| UL 60730-2-9 | Automatic Electrical Controls - Particular Requirements for Temperature Sensing Controls |
+| UL 50E | Enclosures for Electrical Equipment, Environmental Considerations |
+| UL 1203 | Explosion-Proof and Dust-Ignition-Proof Electrical Equipment for Use in Hazardous (Classified) Locations |
+| NEMA 250 | Enclosures for Electrical Equipment (1000 Volts Maximum) |
+| NEMA DC 3 | Residential Controls - Low Voltage Room Thermostats |
+| ANSI/AMCA 500-D | Laboratory Methods of Testing Dampers for Rating |
+| 47 CFR Part 15 | Radio Frequency Devices (Subpart C - intentional radiators) |
# Submittals {toc}
−## The Contractor shall submit the following action submittals for review and approval prior to procurement:
−- Product data for each sensor, transmitter, thermostat, and actuator type, including accuracy, range, output signal, supply voltage, and enclosure rating.
−- A device schedule cross-referenced to the control drawings by ISA-5.1 tag number, listing service, location, range, and accuracy for each point.
−- Shop drawings showing sensor mounting details, immersion well lengths, averaging-element insertion depths, and actuator-to-damper or actuator-to-valve linkage.
−- Actuator torque calculations for each damper, including damper area, blade-seal friction allowance, and applied safety factor.
−- Wiring termination diagrams showing field device to controller terminal assignments and circuit classification per NFPA 70 Article 725.
+## Action Submittals {toc}
+### The Contractor shall submit the following for the Engineer's review and return before any field device is procured or installed:
+
+- Product data for each sensor, transmitter, switch, thermostat, and actuator model, giving range, accuracy, supply voltage, output signal, enclosure rating, and rated ambient conditions
+- Device schedule listing each device by the point name assigned under the building automation system, with its service, location, range, output signal, and enclosure rating
+- Insertion schedule giving the probe length, averaging element length, thermowell insertion length, and the duct or pipe size at each duct-mounted and pipe-mounted sensor
+- Actuator selection schedule listing each damper and valve with the actuator model, the torque or close-off rating, the fail-safe mechanism, the auxiliary switches, and the position feedback furnished
+- Damper actuator torque calculation for each damper, using the damper manufacturer's published close-off torque at the maximum differential pressure across the damper and the torque margin selected under the building automation system
+- Control valve schedule giving, for each control valve, the service, design flow, calculated and selected flow coefficient, pressure drop at design flow, valve authority, body type and size, end connections, body pressure rating, and seat leakage class
+- Status and safety switch schedule giving each switch's type, trip setting, reset action, and the circuit it interrupts
+- Mounting details for space sensors, duct sensors, pipe sensors, outdoor sensors, and pressure pickups
+- Wireless gateway and repeater plan where wireless sensors are furnished
+- Pneumatic device data and control air tubing layout where pneumatic control devices are furnished
+- Sample of each space sensor and thermostat housing offered for occupied spaces, for finish review
+
```datasheet
−label: Action Submittals Required
+label: Required Action Submittals
type: checkbox
options:
− - Product data for each device type
− - Device schedule keyed to ISA-5.1 tags
− - Mounting and insertion shop drawings
− - Damper actuator torque calculations
− - Wiring termination diagrams
+ - "Product data for each device model"
+ - "Device schedule keyed to the building automation system point names"
+ - "Insertion schedule for duct and pipe sensors"
+ - "Actuator selection schedule"
+ - "Damper actuator torque calculations"
+ - "Control valve schedule"
+ - "Status and safety switch schedule with trip settings"
+ - "Mounting details"
+ - "Wireless gateway and repeater plan"
+ - "Pneumatic device data and tubing layout"
+ - "Space sensor and thermostat housing samples"
default:
− - Product data for each device type
− - Device schedule keyed to ISA-5.1 tags
− - Mounting and insertion shop drawings
− - Damper actuator torque calculations
− - Wiring termination diagrams
+ - "Product data for each device model"
+ - "Device schedule keyed to the building automation system point names"
+ - "Insertion schedule for duct and pipe sensors"
+ - "Actuator selection schedule"
+ - "Damper actuator torque calculations"
+ - "Control valve schedule"
+ - "Status and safety switch schedule with trip settings"
+ - "Mounting details"
```
−## The Contractor shall submit the following informational submittals:
−- NIST-traceable factory calibration certificates for all CO2 sensors and for temperature transmitters serving air-handler supply-air and mixed-air points.
−- Manufacturer installation instructions for each device type.
−- A field calibration and point-to-point verification report for every installed device, completed before TAB begins.
+### Where a space sensor or thermostat housing is offered in more than one finish, the Architect shall select the finish from the submitted samples before the devices are procured.
+### The device schedule and the actuator selection schedule shall be submitted together with the point list required under [[sync/building-automation-system]] so that each device can be checked against the point it serves.
+
+## Informational Submittals {toc}
+
+### The Contractor shall submit the following for information before device installation begins:
+
+- Manufacturer's installation instructions for each device model
+- Factory calibration certificates for the device classes selected under Testing
+- Signal compatibility verification listing each device output against the controller input on which it terminates
+- Radio frequency site survey results where wireless sensors are furnished
+
```datasheet
−label: Informational Submittals Required
+label: Required Informational Submittals
type: checkbox
options:
− - Factory calibration certificates (CO2 and critical TT)
− - Manufacturer installation instructions
− - Field calibration and point-to-point report
+ - "Manufacturer's installation instructions"
+ - "Factory calibration certificates for the selected device classes"
+ - "Signal compatibility verification"
+ - "Radio frequency site survey results"
default:
− - Factory calibration certificates (CO2 and critical TT)
− - Manufacturer installation instructions
− - Field calibration and point-to-point report
+ - "Manufacturer's installation instructions"
+ - "Factory calibration certificates for the selected device classes"
+ - "Signal compatibility verification"
```
−## The Contractor shall submit the following closeout submittals:
−- Operation and maintenance data including recommended recalibration intervals for CO2 and humidity sensors.
−- A final as-installed device schedule reflecting field changes, with tag numbers reconciled to the control and mechanical drawings.
+## Closeout Submittals {toc}
+### The Contractor shall submit the following before the field devices are accepted:
+
+- As-installed device schedule reconciled to the record controls drawings
+- As-installed control valve schedule identifying the valve installed at each service
+- Status and safety switch setpoint record giving the as-left trip setting of every switch
+- Actuator stroke and fail-safe test record
+- Wireless sensor signal strength record and the battery installation date for each wireless device
+- Control air tubing pressure test record where pneumatic control devices are furnished
+- Operation and maintenance data giving the recalibration interval, the battery replacement interval, and the part number of every consumable element and module
+
```datasheet
−label: Closeout Submittals Required
+label: Required Closeout Submittals
type: checkbox
options:
− - O&M data with recalibration intervals
− - Final as-installed device schedule
+ - "As-installed device schedule"
+ - "As-installed control valve schedule"
+ - "Status and safety switch setpoint record"
+ - "Actuator stroke and fail-safe test record"
+ - "Wireless signal strength and battery date record"
+ - "Control air tubing pressure test record"
+ - "Operation and maintenance data with recalibration and battery intervals"
default:
− - O&M data with recalibration intervals
− - Final as-installed device schedule
+ - "As-installed device schedule"
+ - "As-installed control valve schedule"
+ - "Status and safety switch setpoint record"
+ - "Actuator stroke and fail-safe test record"
+ - "Operation and maintenance data with recalibration and battery intervals"
```
+### Sensor calibration records shall be submitted as required under [[sync/building-automation-system]] and shall not be duplicated in this closeout package.
+
# Quality Assurance {toc}
−## Devices shall be the products of manufacturers regularly engaged in the production of HVAC field instrumentation and actuators.
+## Listing and Certification {toc}
−## Electronic thermostats, room sensors, and energy-management controllers shall be listed under UL 916.
+### Sensors, transmitters, thermostats, and actuators shall be listed by a Nationally Recognized Testing Laboratory to UL 916, UL 60730-1, or UL 873 as applicable to the product.
−## Thermostats and space sensors shall comply with the applicable safety requirements of UL 60730-1.
+### Low-temperature limit switches, static pressure limit switches, and condensate overflow switches that interrupt equipment operation shall be listed to UL 353 or UL 60730-1.
−## A factory calibration certificate is not a substitute for field verification. {note}
+### Current switches and interposing relays shall be listed to UL 508 or UL 60730-1.
−## Field-installed sensors are frequently shipped uncalibrated or drift during shipping and handling. Requiring a NIST-traceable factory certificate establishes the as-shipped baseline; the field verification below confirms the device still reads true after installation. Both are required for the critical points. {note}
+### Devices supplied from a Class 2 source shall be listed for Class 2 operation in accordance with NFPA 70 Article 725.
−## Installed sensor accuracy shall be field-verified to within 1.5 times the manufacturer's rated accuracy over the device's operating range.
+### Wireless devices shall be certified under 47 CFR Part 15 for the frequency band and the radiated power at which they operate.
−## Sensors failing the field verification tolerance shall be replaced, not adjusted, before TAB begins.
+### Devices installed in classified hazardous locations shall be listed for the class, division, and group present, to UL 1203 where an explosion-proof enclosure is the means of protection.
−## Sensor accuracy shall be re-verified after TAB completion at points affected by balancing.
+## Source Limitation {toc}
−## Sensor tag numbers shall follow ISA-5.1 format.
+### The manufacturer source limitation applying to field devices shall be as indicated in the datasheet.
−## Sensor tag numbers shall be identical across the control, mechanical, and electrical contract documents.
+```datasheet
+label: Field Device Source Limitation
+type: radio
+options:
+ - "Single manufacturer for each device family across the project"
+ - "Single manufacturer for all field devices"
+ - "No source limitation"
+default: "Single manufacturer for each device family across the project"
+```
−## A supply-air temperature transmitter on AHU-1 carried as TT-AHU-1-SA on one drawing set and as something else on another is a guaranteed installation error and a recurring source of controls RFIs. Tag consistency is a quality-assurance requirement, not a drafting nicety. {note}
+### Devices of one family from one manufacturer share a calibration procedure, a spare inventory, and a replacement part, and every additional manufacturer of the same family adds its own. A single manufacturer for every family is offered by fewer suppliers, which narrows the bid list by the same amount that it simplifies the spare shelf. {note}
−# Environmental and Service Conditions {toc}
+## Signal Compatibility {toc}
−## Enclosure type shall be selected for the installed environment per NEMA 250.
+### The controls contractor shall verify that the output of every sensor, transmitter, and switch and the input of every actuator is compatible with the controller terminal on which it lands, and shall record the verification in the device schedule.
−## Enclosure selection is a function of where the device lives, not of the device itself. The same transmitter may be Type 1 in a dry electrical room and Type 4X on a corrosive rooftop. IEC 60529 IP ratings are an acceptable equivalent basis where a manufacturer rates only to the IP code: IP54 is roughly equivalent to NEMA Type 12, and IP65 to NEMA Type 4. {note}
+### Where a device output cannot be terminated directly on the controller input, the signal conditioner, isolator, or interposing relay required shall be furnished and shown in the device schedule at no additional cost to the Owner.
−## Devices in dry, conditioned interior locations shall be furnished in NEMA Type 1 enclosures.
+## Device Identification {toc}
−## Devices in mechanical rooms, boiler rooms, and exterior locations shall be furnished in NEMA Type 4 enclosures.
+### Each device shall be identified in the device schedule and on its label by the point name assigned to it under [[sync/building-automation-system]].
−## Devices in pool, chemical, or other corrosive environments shall be furnished in NEMA Type 4X (stainless) enclosures.
+### Where the contract drawings tag a device under ANSI/ISA-5.1, the device schedule shall list that tag beside the point name.
−## Devices in classified hazardous locations shall be furnished in explosion-proof enclosures listed to UL 1203.
+### A device carried under one identifier on the controls drawings and under another on the mechanical drawings is wired to the wrong terminal often enough that reconciling the two identifiers at submittal is cheaper than reconciling them at point-to-point verification. {note}
+# Environmental and Service Conditions {toc}
+
+## Enclosure Rating {toc}
+
+### Devices mounted outdoors shall be rated for continuous operation between [[parameter: site-ambient-temperature-minimum]] and [[parameter: site-ambient-temperature-maximum]] without loss of published accuracy.
+
+### Field device housings shall carry at least the enclosure rating indicated in the datasheet, rated under NEMA 250 or UL 50E.
+
```datasheet
−label: Device Enclosure Type by Location
+label: Minimum Device Enclosure Rating
type: select
options:
− - "NEMA Type 1 (dry interior)"
− - "NEMA Type 4 (mechanical room, exterior)"
− - "NEMA Type 4X (corrosive / washdown, stainless)"
− - "Explosion-proof, UL 1203 (classified hazardous)"
−default: "NEMA Type 1 (dry interior)"
+ - "NEMA Type 1"
+ - "NEMA Type 2"
+ - "NEMA Type 12"
+ - "NEMA Type 13"
+ - "NEMA Type 3R"
+ - "NEMA Type 4"
+ - "NEMA Type 4X"
+default: "NEMA Type 1"
```
−## Devices shall be rated for the temperature, humidity, and vibration of their installed location without degradation of stated accuracy.
+### Most field devices sit in a conditioned interior, so Type 1 is the default. The clauses that follow raise the rating for the locations that need more, whatever the datasheet selects; a project whose devices are mostly in one harsher class raises the datasheet value instead. {note}
−# Power and Signal {toc}
+### Devices mounted outdoors shall be rated NEMA Type 3R, Type 4, or Type 4X.
−## Sensor and device power shall be 24 VAC or 24 VDC Class 2 per NFPA 70 Article 725.41.
+### A Type 4 enclosure excludes hose-directed water and wind-driven rain; Type 4X adds resistance to corrosion, which matters where the device sits in salt air, cooling tower drift, or a kitchen exhaust plume. Type 3R excludes falling rain and sleet but not water driven against it, so it depends on a hood or a shield for the rest. {note}
−## Class 2 power limiting keeps the field wiring inside the energy thresholds that permit plenum-rated cable without conduit in many jurisdictions and bounds the fault energy at the sensing element. The conductors and raceways themselves are governed by [[sync/conductors-and-cables]] and [[sync/raceways-and-conduit]]; this standard fixes only the device-side voltage and circuit class. {note}
+### Devices mounted where airborne dust, lint, or fibers accumulate shall be rated NEMA Type 12, Type 13, Type 4, or Type 4X.
−## For two-wire 4-20 mA loop-powered devices, maximum loop resistance shall be verified against the specified supply voltage before installation.
+### Devices mounted where dripping or light splashing of a non-corrosive liquid occurs shall be rated NEMA Type 2, Type 12, Type 4, or Type 4X.
−## A 4-20 mA loop has a finite voltage budget. If the sum of the device burden, the wiring resistance, and the controller input resistance exceeds what the supply can drive, the transmitter saturates below 20 mA and the reading clips at the top of the range. This is checked on paper at submittal, not discovered at startup. {note}
+### Devices mounted in locations subject to washdown, hose-directed water, or persistent condensation shall be rated NEMA Type 4 or Type 4X.
−## Sensor supply voltage shall be selected to match the device input requirement.
+### Devices mounted in locations exposed to salt air, chemical fumes, pool chemicals, or cooling tower drift shall be rated NEMA Type 4X.
+### Devices installed in a plenum used for environmental air shall be listed for plenum use or installed in an enclosure listed for that use, in accordance with NFPA 90A and NFPA 70.
+
+## Vibration and Air Density {toc}
+
+### Transmitters and switches shall not be mounted on fan housings, pump casings, or other vibrating equipment.
+
+### Where the sensed point is on vibrating equipment, the transmitter or switch shall be mounted on a fixed surface nearby and connected to the sensed point by tubing or by a remote sensing element.
+
+### Airflow measurement stations and pressure-based flow devices whose calibration depends on air density shall be corrected for [[parameter: altitude]] in the transmitter or in the controller, and the point at which the correction is applied shall be identified in the device schedule.
+
+### A thermal dispersion station measures mass flow and reports it as a standard volumetric rate; a pitot or orifice device measures velocity pressure, which at altitude corresponds to a higher actual velocity than a sea-level calibration assumes. Which device needs the correction, and where it is applied, is what the device schedule entry records. {note}
+
+# Supply and Signal Interface {toc}
+
+## Device Supply Voltage {toc}
+
+### Sensors, transmitters, and switches that require supply power shall be supplied at the voltage indicated in the datasheet from a Class 2 source complying with NFPA 70 Article 725.
+
```datasheet
−label: Sensor Supply Voltage
+label: Sensor and Transmitter Supply Voltage
type: radio
options:
− - "24 VAC, Class 2"
− - "24 VDC, Class 2"
−default: "24 VAC, Class 2"
+ - "Class 2, 24 VAC"
+ - "Class 2, 24 VDC"
+ - "Class 2, 24 VAC or 24 VDC as accepted by each device"
```
−## Device output signal type shall match the receiving BAS controller input.
+### Actuators shall be supplied at the voltage indicated in the datasheet.
```datasheet
−label: Analog Sensor Output Signal
+label: Actuator Supply Voltage
+type: radio
+options:
+ - "Class 2, 24 VAC"
+ - "Class 2, 24 VDC"
+ - "Line voltage, 120 VAC"
+ - "Line voltage, 230 VAC"
+default: "Class 2, 24 VAC"
+```
+
+### Line-voltage actuators shall be supplied from a branch circuit with a disconnecting means within sight of the actuator, in accordance with NFPA 70.
+
+### Devices sharing a control power transformer shall observe the common polarity and single-point secondary grounding required under [[sync/building-automation-system]].
+
+### A half-wave-rectified device on a transformer secondary that also feeds a full-wave device shorts the secondary through the two rectifiers whenever the common conductor is shared, and the fault presents as a transformer that runs hot and a device that resets at random. Which devices are half-wave is stated in the product data and is checked at submittal. {note}
+
+## Transmitter Output Signal {toc}
+
+### Analog transmitters shall deliver the output signal indicated in the datasheet.
+
+```datasheet
+label: Transmitter Output Signal
type: select
options:
− - "4-20 mA"
+ - "Two-wire loop-powered 4-20 mA"
+ - "Three-wire or four-wire 4-20 mA"
- "0-10 VDC"
- "2-10 VDC"
− - "RTD (1000 Ω platinum, direct)"
− - "Thermistor (10k Ω, direct)"
− - "BACnet MS/TP (network)"
−default: "4-20 mA"
+ - "0-5 VDC"
+ - "Networked digital output on the field bus"
```
−# Temperature Sensors {toc}
+### A current loop is unaffected by the voltage drop of a long run and by most induced noise, and a live-zero signal distinguishes an open circuit from a zero reading; a voltage output needs no loop supply calculation and shares a common with the controller, which simplifies the panel wiring where runs are short. Which weighs more depends on the run length and the electrical environment between the device and the panel. {note}
−## Temperature sensing element type shall be selected for the service.
+### For each two-wire current loop, the Contractor shall verify before installation that the sum of the transmitter's minimum operating voltage, the controller input burden at 20 mA, and the loop conductor drop at 20 mA does not exceed the loop supply voltage.
−## For most building points a 10k Ω thermistor gives adequate accuracy at the lowest cost and is the default for space sensing. A 1000 Ω platinum RTD is more linear and stable over a wide span and is preferred for immersion and critical air-handler points. A 4-20 mA transmitter is used where the run length or electrical noise makes a direct-resistance signal unreliable, and a BACnet MS/TP network sensor is used where the project's network architecture favors device-level addressing. {note}
+### Networked field devices shall communicate on the field bus protocol selected under [[sync/building-automation-system]].
−## Space temperature sensors shall be furnished as the selected element type.
+## Temperature Sensor Signal {toc}
+### Temperature sensors shall connect to the controller by the method indicated in the datasheet.
+
```datasheet
−label: Space Temperature Sensor Element
+label: Temperature Sensor Signal
type: radio
options:
− - "10k Ω thermistor"
− - "1000 Ω platinum RTD"
− - "4-20 mA transmitter"
− - "BACnet MS/TP network sensor"
−default: "10k Ω thermistor"
+ - "Direct resistance element wired to the controller input"
+ - "Transmitter with an analog output"
+ - "Networked digital output on the field bus"
+default: "Direct resistance element wired to the controller input"
```
−## Space temperature sensors shall hold their rated accuracy over the full 40°F to 95°F operating range.
+### A direct resistance element has no electronics at the sensor to fail or drift, and a controller input that reads resistance holds the whole measurement chain to one conversion. A transmitter converts the element to a signal that survives long runs and electrically noisy routes, and adds a second calibrated device to every point that has one. {note}
−## An accuracy figure with no stated span is meaningless: a device can be ±0.5°F at 70°F and ±3°F at the ends of its range. Stating the operating span over which the accuracy must hold is what makes the specification enforceable. {note}
+## Discrete Contacts {toc}
−## Space temperature sensor accuracy shall meet the selected class.
+### Status and safety switches shall provide voltage-free contacts rated for the controller input they serve and for the pilot duty of any relay or safety circuit they interrupt.
+### Switches that interrupt equipment operation shall provide a separate contact, or a separately monitored input, so that the building automation system registers the trip without depending on the interrupted circuit.
+
+### Where a switch is hardwired to interrupt equipment operation, the interrupt shall remain effective with the equipment's hand-off-auto selector and any drive bypass in every position.
+
+### A safety contact wired into the automatic leg of a hand-off-auto selector is bypassed the moment the selector is turned to hand, which is the position it is usually left in while the fault is being found. {note}
+
+## Interposing Relays {toc}
+
+### Interposing relays between a controller output and an equipment control circuit shall be of the type indicated in the datasheet.
+
```datasheet
−label: Space Temperature Sensor Accuracy
−type: radio
+label: Interposing Relay Type
+type: select
options:
− - "Standard, ±1.0°F (±0.5°C)"
− - "High-accuracy, ±0.5°F (±0.25°C) for critical/laboratory spaces"
−default: "Standard, ±1.0°F (±0.5°C)"
−unit: °F
+ - "Plug-in relay in a socket with a status indicator"
+ - "DIN-rail interface relay with a status indicator"
+ - "Enclosed relay module with a manual override switch"
+ - "Solid-state relay"
```
−## Space temperature sensors shall be located to read representative occupied-zone conditions.
+### A plug-in relay is replaced without touching a wire; a DIN-rail interface relay takes the least panel space; an enclosed module with a manual override lets a technician run the equipment with the controller output failed; a solid-state relay has no contacts to wear and, when it fails, more often fails conducting than open, which decides whether it belongs in a safety circuit. {note}
−## Poor sensor placement is the single most common cause of comfort complaints that no amount of controller tuning can fix. Sensors on exterior walls read the wall, not the room; sensors under a supply diffuser read the supply air; sensors near a radiant panel or in direct solar gain read the source, not the occupant. {note}
+### Relay contacts shall be rated for the voltage, current, and load type of the circuit they switch, including the inrush current of any starter or contactor coil.
−## Space temperature sensors shall be mounted a minimum of 5 ft from any heat source and 18 in from the nearest supply register per ASHRAE Guideline 13.
+### Relays located outside a controller panel shall be mounted in an enclosure at the equipment served and shall not be concealed above a fixed ceiling without an access panel.
−## Space temperature sensors shall not be located on exterior walls, above ceiling supply diffusers, adjacent to radiant panels, or in positions subject to direct solar radiation.
+## Wireless Sensors {toc}
−## Space sensor location shall be coordinated with the architectural reflected ceiling and elevation drawings. [[drawing: space sensor mounting locations]]
+### Wireless sensors shall be used only as permitted by the policy indicated in the datasheet.
−## Duct and mixed-air temperature sensors shall be averaging type with the selected insertion length.
+```datasheet
+label: Wireless Sensor Policy
+type: radio
+options:
+ - "Not permitted"
+ - "Permitted at locations designated by the Engineer"
+ - "Permitted for space-mounted sensors at the Contractor's option"
+ - "Permitted for any sensor at the Contractor's option"
+default: "Permitted at locations designated by the Engineer"
+```
+### Where wireless sensors are permitted, the radio technology shall be as indicated in the datasheet.
+
```datasheet
−label: Duct Averaging Temperature Sensor Insertion Length
+label: Wireless Sensor Radio Technology
type: select
options:
− - "12 in"
− - "18 in"
− - "24 in"
−default: "18 in"
−unit: in
+ - "Proprietary sub-gigahertz mesh"
+ - "IEEE 802.15.4 mesh, Zigbee or Thread"
+ - "EnOcean"
+ - "Bluetooth mesh"
+ - "Wi-Fi"
```
−## Duct, mixed-air, immersion, and outdoor temperature sensors shall hold ±0.5°F accuracy at 70°F.
+### Wireless sensors shall be powered as indicated in the datasheet.
−## Factory calibration certificates shall be furnished for air-handler supply-air and mixed-air temperature sensors.
+```datasheet
+label: Wireless Sensor Power Source
+type: radio
+options:
+ - "Replaceable battery"
+ - "Energy harvesting from ambient light or temperature difference"
+ - "Wired supply with a wireless signal"
+default: "Replaceable battery"
+```
−## Mixed-air sensors shall be of sufficient averaging length to span the full duct cross-section.
+### Battery-powered wireless sensors shall have a published battery life, at the sensor's configured reporting interval, of not less than the period indicated in the datasheet.
−## Mixed air stratifies: the cold outdoor stream and the warm return stream do not blend completely within the mixing box. A short single-point sensor placed in either stream reports a temperature that does not exist anywhere the air is actually delivered, which corrupts every economizer and freeze-protection decision downstream. A serpentine averaging element that crosses the full duct face is the only reliable way to read true mixed-air temperature. {note}
+```datasheet
+label: Minimum Wireless Sensor Battery Life
+type: range
+unit: years
+min: 1
+max: 10
+setpoints: [1, 2, 3, 5, 7, 10]
+default: 5
+```
−## Immersion temperature sensors in hydronic piping shall be furnished with thermowells of the selected insertion length.
+### Each wireless sensor shall report its battery condition and its link quality as points to the building automation system.
+### Wireless sensors shall be installed only after a radio frequency site survey has identified the gateway and repeater locations, and the repeaters the survey requires shall be furnished at no additional cost to the Owner.
+
+### Wireless sensor batteries shall be replaceable without removing ceiling finishes, equipment access panels, or the sensor's mounting.
+
+### Mechanical rooms, elevator lobbies, and rooms with metal-lined walls attenuate a radio signal enough that a mesh that tested well in an open shell fails after the equipment and the finishes go in. A survey taken at rough-in is a prediction; the signal strength record at closeout is the evidence. {note}
+
+# Space Sensors and Thermostats {toc}
+
+## Space Sensor Housing {toc}
+
+### Space sensor housings shall be as indicated in the datasheet.
+
```datasheet
−label: Immersion Sensor Thermowell Insertion Length
+label: Space Sensor Housing
type: select
options:
− - "2.5 in"
− - "4 in"
− - "6 in"
−default: "4 in"
−unit: in
+ - "Thermoplastic wall housing"
+ - "Metal wall plate, flush to the wall"
+ - "Thermoplastic housing with a locking tamper-resistant cover"
+ - "Housing with a wire guard"
+ - "Impact-rated housing"
+default: "Thermoplastic wall housing"
```
−## Immersion sensors in systems above 140°F, or in any system requiring sensor replacement under pressure, shall be installed in thermowells.
+### Tamper-resistant covers or guards shall be provided on space sensors in [[drawing: the areas designated on the controls drawings]] regardless of the housing selected above.
−## A thermowell lets a sensor be pulled and replaced without draining the system or scalding the technician, and it isolates the element from the pressure boundary. Thermowell length and insertion depth must match the pipe diameter and the sensor element length so the tip sits in the flowing stream, not in a stagnant boundary layer at the wall. Coordinate the immersion taps with [[sync/hydronic-piping]]. {note}
+### The visible face of a space sensor is an architectural element in a finished room, which is why the finish review under Submittals precedes procurement rather than following installation. {note}
−## Outdoor air temperature and humidity sensors shall be furnished in a NEMA 4X housing with a passive radiation shield.
+### Space sensors shall be mounted on a device box, and the box and any conduit entering it shall be sealed so that air from the wall cavity cannot reach the sensing element.
−## A bare outdoor sensor in sunlight reads the solar load on its own housing, not the air, and can run many degrees high on a clear day. A ventilated radiation shield is what makes an outdoor reading usable for economizer and reset logic. {note}
+### A sensor on an unsealed box reads a mix of room air and wall-cavity air, and the cavity air moves with stack effect and wind, so the error changes through the day and cannot be calibrated out. {note}
−# Humidity Sensors {toc}
+## Occupant Interface {toc}
−## Humidity sensing technology shall be capacitive thin-film polymer.
+### Space sensors shall display the information indicated in the datasheet.
−## Capacitive thin-film elements are the building-controls standard: they recover from saturation, resist contamination better than bulk-polymer elements, and hold accuracy over a wide range. Bulk-polymer elements are cheaper but drift faster and are reserved for non-critical monitoring. {note}
+```datasheet
+label: Space Sensor Display
+type: radio
+options:
+ - "No display"
+ - "Space temperature"
+ - "Space temperature and setpoint"
+ - "Space temperature, setpoint, mode, and fan status"
+```
−## Humidity sensor accuracy shall meet the selected class.
+### Occupant adjustment of the space temperature setpoint shall be as indicated in the datasheet.
```datasheet
−label: Humidity Sensor Accuracy
+label: Occupant Setpoint Adjustment
type: radio
options:
− - "Standard, ±3% RH (capacitive)"
− - "Precision, ±2% RH (data center, archival)"
−default: "Standard, ±3% RH (capacitive)"
−unit: "% RH"
+ - "No occupant adjustment"
+ - "Offset adjustment within a band set at the building automation system"
+ - "Absolute setpoint adjustment within limits set at the building automation system"
+ - "Unrestricted setpoint adjustment"
```
−## Combined temperature/humidity elements shall be furnished where both points are required at the same location.
+### Where offset adjustment is selected, the adjustment band on each side of the scheduled setpoint shall not exceed the value indicated in the datasheet.
```datasheet
−label: Humidity Sensor Configuration
+label: Maximum Occupant Setpoint Offset
+type: range
+unit: °F
+min: 1
+max: 5
+setpoints: [1, 2, 3, 4, 5]
+```
+
+### An occupancy override button shall be provided on space sensors as indicated in the datasheet.
+
+```datasheet
+label: Occupancy Override Button
type: radio
options:
− - "Combined temperature/humidity element"
− - "Separate humidity element"
−default: "Combined temperature/humidity element"
+ - "Provided on every space sensor"
+ - "Provided on sensors serving zones with unoccupied periods"
+ - "Not provided"
```
−## Duct-mounted humidity sensors shall be located a minimum of three duct widths downstream of any cooling coil.
+### The override duration and the setpoint limits enforced at the building automation system are sequence parameters set under [[sync/building-automation-system]]; the sensor furnishes the button and the adjustment input, not the rule. The sequences of ANSI/ASHRAE Guideline 36 assume both inputs exist at the zone and hold the timer and the limits in the controller. {note}
−## Air leaving a cooling coil at part load is at or near saturation, and condensate carried onto a capacitive element destroys it. Locating the sensor well downstream gives the air room to mix and warm above its dew point before it reaches the element. {note}
+### Setpoint adjustment and override inputs on a networked space sensor shall be readable and writable from the building automation system so that the adjustment band and the override duration can be changed without visiting the sensor.
−## Duct-mounted humidity sensors in condensation-prone locations shall include a condensation-protection provision such as a hydrophobic filter or heated element.
+## Unitary Equipment Thermostats {toc}
−# Differential-Pressure Transmitters {toc}
+### Equipment controlled by a thermostat rather than by a field controller shall be as indicated on [[drawing: the mechanical equipment schedules]].
−## Differential-pressure transmitters shall be electronic piezoresistive type.
+### Thermostats shall comply with NEMA DC 3 and shall be listed to UL 873 or UL 60730-2-9.
−## Piezoresistive transmitters are stable, have no moving linkage to wear, and provide a clean analog or network output. Mechanical pressure switches and gauges are reserved for simple local indication and high/low limit safeties, not for the modulating control and reset inputs this section covers. {note}
+### Thermostat integration with the building automation system shall be as indicated in the datasheet.
−## Differential-pressure transmitter range shall be selected so the design setpoint falls at 50% to 60% of full scale.
+```datasheet
+label: Thermostat Integration
+type: radio
+options:
+ - "Communicating thermostat on the field bus"
+ - "Standalone thermostat with a status contact monitored by the building automation system"
+ - "Standalone thermostat, not monitored"
+ - "Cloud-managed thermostat with an internet connection"
+default: "Communicating thermostat on the field bus"
+```
−## A transmitter operating at the bottom of its range wastes resolution and amplifies sensor noise into the control loop; one operating near full scale clips during transients. Placing the design setpoint near mid-scale gives headroom in both directions and the best signal-to-noise for reset control. {note}
+### A communicating thermostat exposes its setpoint, mode, and space temperature to the operator for scheduling, reset, and trending; a standalone thermostat with a status contact tells the operator only that the equipment is running; an unmonitored thermostat is invisible to the system. The cost of each step up is a field bus drop or a monitored input, which is what makes the choice one of network reach rather than device price. A cloud-managed thermostat gives the Owner scheduling and remote access through the vendor's service without a field bus drop, and puts the schedule, the history, and the access behind an internet account and the vendor's continued operation of that service. {note}
−## Duct static pressure transmitters shall be furnished with the selected range and ±1% full-scale accuracy.
+### Standalone thermostat scheduling capability shall be as indicated in the datasheet.
```datasheet
−label: Duct Static Pressure Transmitter Range
−type: select
+label: Standalone Thermostat Scheduling
+type: radio
options:
− - "0 to 1 in WC (terminal duct)"
− - "0 to 3 in WC (AHU supply duct)"
− - "0 to 5 in WC"
−default: "0 to 3 in WC (AHU supply duct)"
−unit: in WC
+ - "Seven-day programmable with a holiday schedule"
+ - "Seven-day programmable"
+ - "Non-programmable"
```
−## Duct static pressure sensors shall be located approximately two-thirds of the way down the longest duct run, not at the air-handler discharge.
+### Where the thermostat is the only automatic control on the equipment, the scheduled shutoff that [[parameter: adopted-energy-code]] requires is performed by the thermostat, and a non-programmable thermostat satisfies it only where the code exempts that equipment. {note}
−## ASHRAE Guideline 36 requires the static pressure sensor be located remote from the fan. Sensing at the discharge makes the static-pressure-reset logic travel a much wider band than necessary and starves the terminal boxes at the end of the run, the exact opposite of what duct static reset is meant to achieve. {note}
+### Thermostats shall enforce a deadband between the heating and cooling setpoints of not less than the value required by [[parameter: adopted-energy-code]].
−## Duct static pressure sensor location shall be coordinated with the ductwork layout. [[drawing: duct static sensor location]]
+### Thermostats shall provide keypad lockout and setpoint range limits configurable by the Owner.
−## Building (room differential) static pressure transmitters shall be furnished with a ±0.25 in WC range and ±1% full-scale accuracy.
+### Thermostats serving heat pumps shall be furnished with the auxiliary heat staging, the emergency heat mode, and the reversing valve output that the served equipment requires.
−## Hydronic differential-pressure transmitters shall be furnished with the selected range and ±0.5% full-scale accuracy.
+### Line-voltage thermostats controlling electric heaters directly shall be rated for the connected load and listed to UL 873.
+## Cloud-Managed Thermostats {toc}
+
+### Requirements in this article apply where a cloud-managed thermostat is selected under Thermostat Integration.
+
+### A cloud-managed thermostat shall not be connected to the building automation network unless the connection is identified and accepted in the cybersecurity plan required under [[sync/building-automation-system]].
+
+### Each cloud-managed thermostat shall be enrolled in a service account held in the Owner's name.
+
+### The Contractor shall transfer the credentials of the service account to the Owner at closeout.
+
+### The factory default credentials of each cloud-managed thermostat shall be changed before the thermostat is placed in service.
+
+### A thermostat managed through a vendor's service depends on that service staying in operation, on the building's internet connection, and on whoever holds the account; an account opened in the installer's name leaves the site with the installer. {note}
+
+# Temperature Sensor Assemblies {toc}
+
+## Sensing Element and Measurement Error {toc}
+
+### The temperature sensing element, the lead-wire compensation for low-resistance elements, and the maximum combined measurement error shall be as selected under [[sync/building-automation-system]].
+
+### Each sensor assembly shall hold the combined measurement error over the range of conditions its mounting location produces.
+
+## Duct Sensors {toc}
+
+### Single-point duct sensors shall be rigid probes inserted to the depth indicated in the datasheet.
+
```datasheet
−label: Hydronic Differential-Pressure Transmitter Range
+label: Single-Point Duct Probe Insertion Depth
+type: range
+unit: in.
+min: 4
+max: 24
+setpoints: [4, 6, 8, 12, 18, 24]
+derived: "the duct depth at the mounting location, placing the element tip near the duct centerline"
+default: derived
+```
+
+### A duct probe shorter than half the duct depth reads the boundary layer near the wall, which lags the core airflow on every temperature change and reads closer to the mechanical room than to the air. {note}
+
+### Where an averaging element is required under [[sync/building-automation-system]], the element construction shall be as indicated in the datasheet.
+
+```datasheet
+label: Averaging Element Construction
+type: radio
+options:
+ - "Flexible capillary averaging element supported on clips"
+ - "Rigid multi-point averaging probe"
+default: "Flexible capillary averaging element supported on clips"
+```
+
+### The averaging element length shall be as indicated in the datasheet.
+
+```datasheet
+label: Averaging Element Length
+type: range
+unit: ft
+min: 4
+max: 48
+setpoints: [4, 8, 12, 16, 24, 32, 48]
+derived: "the duct cross-sectional area at the mounting location and the averaging element coverage ratio selected under the building automation system standard"
+default: derived
+```
+
+### Averaging elements shall be arranged in a serpentine pattern that covers the duct cross-section.
+
+### Averaging elements shall be supported on clips at the intervals published by the manufacturer and held clear of the duct wall and the coil face.
+
+### Duct sensors shall be mounted through a gasketed flange or a sealed bushing so that the duct penetration is airtight.
+
+## Pipe Sensors and Thermowells {toc}
+
+### Pipe temperature sensors shall be mounted by the method indicated in the datasheet.
+
+```datasheet
+label: Pipe Temperature Sensor Mounting
+type: radio
+options:
+ - "Immersion element in a thermowell"
+ - "Direct immersion element without a well"
+ - "Surface-mounted strap-on element beneath the insulation"
+default: "Immersion element in a thermowell"
+```
+
+### Where strap-on elements are used, they shall be clamped to a cleaned bare pipe surface with a thermally conductive compound and covered by the pipe insulation.
+
+### A strap-on element reads the pipe wall, which lags the fluid on every change and reads low on hot water and high on chilled water by an amount that depends on the insulation over it. Where the sequence uses the reading for a differential or a reset, that lag is the error the loop then chases. {note}
+
+### Thermowells shall be furnished for every immersion sensor in a pressurized system.
+
+### Thermowell material shall be as indicated in the datasheet.
+
+```datasheet
+label: Thermowell Material
+type: radio
+options:
+ - "Brass"
+ - "Type 304 stainless steel"
+ - "Type 316 stainless steel"
+default: "Brass"
+```
+
+### Thermowells in steam, condensate, and high-temperature hot water service shall be stainless steel regardless of the selection above.
+
+### Thermowell insertion length shall be as indicated in the datasheet.
+
+```datasheet
+label: Thermowell Insertion Length
+type: range
+unit: in.
+min: 2.5
+max: 12
+setpoints: [2.5, 4, 6, 8, 10, 12]
+derived: "the nominal pipe size at the tap, placing the element tip within the center third of the pipe"
+default: derived
+```
+
+### The thermowell connection size and the tap location shall be coordinated with the piping furnished under [[sync/hydronic-piping]] and [[sync/chilled-and-condenser-water-piping]].
+
+### Where the pipe is too small for the insertion length, the thermowell shall be installed in an elbow or a tee with the tip pointing upstream, or in an enlarged section of pipe.
+
+### Immersion elements shall be spring-loaded against the well bottom, and the well shall be filled with a thermally conductive compound before the element is inserted.
+
+### Calibration test wells for checking immersion sensors against a reference thermometer shall be provided as indicated in the datasheet.
+
+```datasheet
+label: Calibration Test Wells at Immersion Sensors
+type: radio
+options:
+ - "Provided at every immersion sensor"
+ - "Provided at immersion sensors serving central plant control and energy calculations"
+ - "Not provided"
+```
+
+### Each calibration test well shall be installed in the same straight section of pipe as the sensor it serves, with no branch, coil, or heat source between the two.
+
+### A test well lets the installed sensor be compared with a reference probe in the same water without pulling the sensor or interrupting control; without one, every later check disturbs the reading it is meant to verify, and the plant sensors that feed an energy calculation are the ones checked most often. {note}
+
+## Outdoor Air Sensors {toc}
+
+### Outdoor air temperature and humidity sensors shall be housed in the radiation shield indicated in the datasheet.
+
+```datasheet
+label: Outdoor Sensor Radiation Shield
+type: radio
+options:
+ - "Passive multi-plate radiation shield"
+ - "Fan-aspirated radiation shield"
+ - "Louvered sun hood integral to the sensor housing"
+default: "Passive multi-plate radiation shield"
+```
+
+### A fan-aspirated shield draws air across the element continuously and removes the residual solar error that a passive shield leaves in still air, at the cost of a powered fan that can fail silently; the failure shows as a reading that drifts high on calm sunny afternoons. {note}
+
+### Outdoor air sensors shall be mounted where indicated on [[drawing: the controls drawings]], at a location meeting the exposure requirements of [[sync/building-automation-system]].
+
+## Combined Sensors {toc}
+
+### Where temperature and humidity are both measured at one location, the sensor arrangement shall be as indicated in the datasheet.
+
+```datasheet
+label: Combined Temperature and Humidity Sensing
+type: radio
+options:
+ - "Combined temperature and humidity sensor in one housing"
+ - "Separate temperature and humidity sensors"
+default: "Combined temperature and humidity sensor in one housing"
+```
+
+# Humidity, Carbon Dioxide, and Air Quality Sensors {toc}
+
+## Humidity Sensor Hardware {toc}
+
+### The humidity sensing technology, the maximum combined humidity measurement error, and the recalibration interval shall be as selected under [[sync/building-automation-system]].
+
+### The humidity sensing element shall be protected by the filter indicated in the datasheet.
+
+```datasheet
+label: Humidity Element Filter
type: select
options:
− - "0 to 30 PSI (chilled/hot water ≤150 PSI systems)"
− - "0 to 50 PSI"
−default: "0 to 30 PSI (chilled/hot water ≤150 PSI systems)"
−unit: PSI
+ - "Sintered stainless steel filter cap"
+ - "PTFE membrane filter"
+ - "Slotted cover without a filter"
```
−## Filter differential-pressure transmitters shall be ranged to read clean-to-final pressure drop across the served filter bank.
+### A sintered or membrane filter keeps dust and droplets off the polymer element and slows its response by seconds to a minute; an open cover responds fastest and fouls first. Duct and outdoor elements see dust and condensate that a room element does not, so the filter choice follows the mounting location. {note}
−# CO2 and Demand-Controlled Ventilation {toc}
+### Duct humidity sensors shall be located downstream of any cooling coil or humidifier by not less than the humidifier's published absorption distance and not less than the distance indicated in the datasheet.
−## CO2 sensors shall be non-dispersive infrared (NDIR) type.
+```datasheet
+label: Minimum Distance of Duct Humidity Sensor Downstream of Coil or Humidifier
+type: range
+unit: ft
+min: 3
+max: 30
+setpoints: [3, 5, 10, 15, 20, 30]
+```
−## NDIR is the only technology accurate and stable enough for ventilation control. Dual-beam NDIR, which uses a reference wavelength to cancel lamp aging and window fouling, is preferred over single-beam for long-term stability without constant recalibration. {note}
+### Humidity sensors mounted where the air can reach saturation shall be furnished with a heated sensing element or a condensation-tolerant element.
−## ASHRAE 90.1-2022 Section 6.4.3 mandates demand-controlled ventilation for zones with a design occupant density of 25 people or more per 1000 ft². {note}
+## Carbon Dioxide Sensor Hardware {toc}
−## Where the energy code triggers DCV, CO2 sensing is the input that drives it, so the sensor selection below is code-driven, not optional, for those zones. ASHRAE 62.1-2022 governs the ventilation calculation the DCV logic executes. {note}
+### Carbon dioxide measurement technology, range, combined measurement error, and automatic background calibration shall be as selected under [[sync/building-automation-system]].
−## CO2 sensors shall be furnished with the selected technology and range.
+### Each zone for which [[parameter: adopted-energy-code]] requires demand-controlled ventilation shall be provided with the carbon dioxide sensor or occupant-count sensor indicated on [[drawing: the points list]].
+### Carbon dioxide sensors shall be mounted as indicated in the datasheet.
+
```datasheet
−label: CO2 Sensor Technology and Range
+label: Carbon Dioxide Sensor Mounting
+type: radio
+options:
+ - "Wall-mounted in the zone"
+ - "Duct-mounted in the return air"
+default: "Wall-mounted in the zone"
+```
+
+### A return-air sensor reads the flow-weighted average of every zone on the system, so on a multiple-zone system it cannot detect one crowded room; on a single-zone system it reads the same air a wall sensor would, without a device on the wall. {note}
+
+### Wall-mounted carbon dioxide sensors shall not be mounted within 3 ft of a door, an operable window, or a supply air outlet, or within the exhalation path of a seated occupant.
+
+### Carbon dioxide sensor modules shall be as indicated in the datasheet.
+
+```datasheet
+label: Carbon Dioxide Sensor Module
+type: radio
+options:
+ - "Field-replaceable sensing module"
+ - "Sealed sensor replaced as a unit"
+```
+
+### Wall-mounted carbon dioxide sensors shall display as indicated in the datasheet.
+
+```datasheet
+label: Carbon Dioxide Sensor Display
+type: radio
+options:
+ - "No display"
+ - "Concentration display"
+```
+
+### An outdoor carbon dioxide reference sensor shall be provided as indicated in the datasheet.
+
+```datasheet
+label: Outdoor Carbon Dioxide Reference Sensor
+type: radio
+options:
+ - "Provided"
+ - "Not provided"
+default: "Not provided"
+```
+
+### Demand-controlled ventilation sequences compute the ventilation rate from the difference between the zone concentration and the outdoor concentration. A fixed outdoor value is correct on average and wrong on any given afternoon; a measured value removes that error at the cost of one more sensor to calibrate, and the error is larger where the outdoor concentration runs well above the rural baseline, as it does near traffic and in dense districts. {note}
+
+## Additional Air Quality Sensing {toc}
+
+### Where the sequence of operations uses indoor air quality parameters beyond carbon dioxide, sensors for the parameters indicated in the datasheet shall be furnished.
+
+```datasheet
+label: Additional Indoor Air Quality Parameters Sensed
+type: checkbox
+options:
+ - "Total volatile organic compounds"
+ - "Particulate matter, PM2.5"
+ - "Particulate matter, PM10"
+ - "Carbon monoxide in occupied spaces"
+ - "None"
+```
+
+### Metal-oxide volatile organic compound sensors report a relative index rather than a concentration traceable to a reference, and two sensors of the same model in the same room can disagree; what they measure reliably is change over time at one location. Optical particulate sensors count particles by light scattering and infer mass, so their reading depends on the particle size distribution assumed at calibration. {note}
+
+### Air quality sensors serving an indoor air quality procedure under ANSI/ASHRAE 62.1 shall meet the accuracy that procedure assigns to the parameter measured.
+
+### Carbon monoxide detection in parking structures and combustion equipment rooms is governed by [[sync/gas-detection-systems]] and is not furnished under this standard. {note}
+
+# Pressure Transmitters and Switches {toc}
+
+## Pressure Transmitter Hardware {toc}
+
+### Duct static and hydronic pressure sensor ranges and the maximum pressure measurement error shall be as selected under [[sync/building-automation-system]].
+
+### The sensing element of differential pressure transmitters shall be as indicated in the datasheet.
+
+```datasheet
+label: Differential Pressure Sensing Element
type: select
options:
− - "Dual-beam NDIR, auto-calibrating, 0-2000 ppm"
− - "Dual-beam NDIR, 0-5000 ppm"
− - "Single-beam NDIR, 0-2000 ppm"
−default: "Dual-beam NDIR, auto-calibrating, 0-2000 ppm"
−unit: ppm
+ - "Piezoresistive silicon"
+ - "Variable capacitance"
+ - "Variable reluctance"
+ - "Thermal mass flow bridge"
```
−## CO2 sensors shall meet an accuracy of ±50 ppm or ±3% of reading, whichever is greater, per ASHRAE 62.1.
+### Capacitance and reluctance elements resolve the very low pressures of building static and terminal duct measurement with less zero drift than a piezoresistive element of the same range; a piezoresistive element withstands overpressure and shock better and costs less at ranges above a few inches of water. A thermal bridge measures the leakage flow through an internal orifice and suits ranges below a tenth of an inch of water. {note}
−## CO2 sensors shall warm up to within stated accuracy in 3 minutes or less.
+### Transmitters shall withstand, without damage or calibration shift, an overpressure of not less than the fan shutoff pressure for air service and the pump shutoff head for hydronic service, and the published proof pressure shall be shown in the product data.
−## Automatic baseline calibration (ABC) shall be disabled in continuously occupied (24/7) spaces.
+### Transmitters shall provide zero and span adjustment accessible without removing the transmitter from its mounting.
−## CO2 sensors in continuously occupied spaces shall be manually recalibrated every 12 months.
+### Transmitters shall be furnished with a local display as indicated in the datasheet.
−## ABC logic assumes the space empties and falls to outdoor CO2 concentration at least once every seven days, then resets its zero to that low point. A 24/7 facility never reaches that baseline, so ABC drifts its zero upward and reports falsely low CO2, which starves the space of ventilation exactly when it is occupied. In those spaces ABC must be turned off and the sensor calibrated by hand on a schedule. {note}
+```datasheet
+label: Pressure Transmitter Local Display
+type: radio
+options:
+ - "No local display"
+ - "Integral digital display"
+```
−## ABC selection shall be set per the space occupancy pattern.
+### Building static pressure transmitters shall be bidirectional with a range centered on zero.
+### The full-scale range of building static pressure transmitters in each direction shall be as indicated in the datasheet.
+
```datasheet
−label: CO2 Sensor Auto-Baseline Calibration (ABC)
+label: Building Static Pressure Range, Each Direction
+type: range
+unit: 'in. w.g.'
+min: 0.05
+max: 1
+setpoints: [0.05, 0.1, 0.25, 0.5, 1]
+drawing_ref: "the points list"
+default: deferred
+```
+
+### The outdoor reference for building static pressure shall be sensed through a static pressure probe shielded from wind and rain, mounted [[drawing: where indicated on the controls drawings]].
+
+### An unshielded outdoor reference reads the wind's velocity pressure as a change in building pressure, and the building pressurization loop then chases every gust. {note}
+
+## Pressure Pickups and Connections {toc}
+
+### Duct static pressure pickups shall be as indicated in the datasheet.
+
+```datasheet
+label: Duct Static Pressure Pickup
type: radio
options:
− - "ABC enabled (intermittently occupied spaces)"
− - "ABC disabled, manual recalibration every 12 months (continuously occupied)"
−default: "ABC enabled (intermittently occupied spaces)"
+ - "Multi-port static pressure probe"
+ - "Single-point tube with a static pressure tip"
+ - "Flush duct wall tap"
+default: "Multi-port static pressure probe"
```
−## An outdoor CO2 reference sensor shall be provided where required to baseline high-occupancy DCV calculations.
+### A multi-port probe averages several sensing ports across a short span of duct and is insensitive to the small velocity component that a single tip picks up when it is not exactly parallel to the flow. A flush wall tap is the cheapest and reads velocity pressure as static wherever the flow is not parallel to the wall. {note}
+### Hydronic pressure transmitters shall be connected through the manifold indicated in the datasheet.
+
```datasheet
−label: Outdoor CO2 Reference Sensor
+label: Hydronic Pressure Transmitter Manifold
type: radio
options:
− - "Provided (high-occupancy / urban baseline)"
− - "Not provided (assume 400 ppm outdoor baseline)"
−default: "Not provided (assume 400 ppm outdoor baseline)"
+ - "Three-valve manifold"
+ - "Five-valve manifold"
+ - "Isolation valves without an equalizing valve"
```
−## ASHRAE 62.1 DCV math assumes a 400 ppm outdoor baseline. Actual outdoor CO2 at grade in dense urban locations runs 450 to 600 ppm, so a fixed 400 ppm assumption systematically under-ventilates. A measured outdoor reference removes that error in high-occupancy buildings; smaller projects in clean-air locations may omit it. {note}
+### A three-valve manifold provides two isolation valves and an equalizing valve, so the transmitter can be zeroed under line pressure and removed without draining; a five-valve manifold adds vent valves for bleeding and test connections. Without an equalizing valve, zeroing requires isolating the transmitter from both taps and venting it. {note}
−# Occupancy Sensors {toc}
+### Hydronic pressure sensing lines shall include a snubber or a pulsation dampener where the transmitter is within ten pipe diameters downstream of a pump discharge or a modulating valve.
−## Occupancy sensors tied into the HVAC control loop shall use the selected sensing technology.
+### Air pressure sensing tubing runs longer than the length the transmitter manufacturer publishes for the specified response time shall be identified in the device schedule with the response time they produce.
+## Pressure Switches {toc}
+
+### Air filter condition shall be sensed by the method indicated in the datasheet.
+
```datasheet
−label: HVAC Occupancy Sensor Technology
+label: Air Filter Condition Sensing
type: radio
options:
− - "Passive infrared (PIR) only"
− - "Dual-technology (PIR + ultrasonic/microwave)"
−default: "Dual-technology (PIR + ultrasonic/microwave)"
+ - "Differential pressure transmitter reporting a continuous value"
+ - "Differential pressure switch with an adjustable setpoint"
+ - "Differential pressure switch and a local gauge"
+ - "Local gauge without a signal to the building automation system"
+ - "No filter condition sensing"
+default: "Differential pressure transmitter reporting a continuous value"
```
−## Passive infrared (PIR) alone detects motion and is adequate where occupants move regularly. Dual-technology sensors add ultrasonic or microwave detection and hold occupancy through low-motion activity such as seated desk work, preventing the HVAC from prematurely dropping a still-occupied zone to setback. This sensor is the HVAC loop's occupancy input only; sensors used solely for lighting are governed by [[sync/lighting-controls]]. {note}
+### A transmitter reports the pressure drop as it rises and lets the operator trend the filter loading and schedule the change; a switch reports only that its setpoint has been crossed, and the setpoint is right at one airflow, because the pressure drop across a filter at a given loading falls with the square of airflow on a variable-volume system. {note}
−## Occupancy sensors shall provide a discrete output to the HVAC controller for occupied/unoccupied determination.
+### Duct high and low static pressure limit switches shall be provided where indicated on [[drawing: the controls drawings]].
−## Occupancy sensor coverage and mounting location shall be coordinated with the served zone. [[drawing: occupancy sensor coverage]]
+### Static pressure limit switches shall be hardwired to interrupt the fan safety circuit.
−# Thermostats {toc}
+### Static pressure limit switch reset shall be as indicated in the datasheet.
−## Electronic thermostats for unitary and terminal equipment shall be UL 916 listed and shall comply with UL 60730-1.
+```datasheet
+label: Static Pressure Limit Switch Reset
+type: radio
+options:
+ - "Manual reset at the switch"
+ - "Automatic reset"
+ - "Manual reset from the building automation system"
+default: "Manual reset at the switch"
+```
−## Thermostats serving BAS-integrated equipment shall communicate to the controller over the project network protocol.
+### A limit switch that resets itself restarts the fan into the same condition that tripped it, so the duct sees the overpressure again on every cycle; the manual reset exists to make someone find the closed damper first. {note}
−## A networked thermostat exposes its setpoint, mode, and space temperature to the BAS for scheduling, reset, and trending. A standalone thermostat is an island the operator cannot see or override remotely, acceptable only where the served equipment is genuinely outside the BAS scope. {note}
+### Pressure switches shall have a trip setpoint adjustable over a range that includes the value on the switch schedule, with the setpoint scale visible without removing the cover.
−## Thermostat communication and adjustment scope shall be selected for the application.
+# Equipment Status and Safety Switches {toc}
+## Fan and Pump Status {toc}
+
+### The running status of constant-speed fans and pumps shall be sensed by the method indicated in the datasheet.
+
```datasheet
−label: Thermostat Type
+label: Status Sensing - Constant-Speed Fans and Pumps
type: radio
options:
− - "BACnet MS/TP networked thermostat"
− - "Standalone electronic thermostat (non-networked)"
−default: "BACnet MS/TP networked thermostat"
+ - "Current switch on a motor lead"
+ - "Differential pressure switch across the fan or pump"
+ - "Starter auxiliary contact"
+ - "Flow switch in the discharge"
+default: "Current switch on a motor lead"
```
−## User-adjustable setpoint range and override authority shall be limited to the values established by the project's energy and comfort requirements.
+### The running status of drive-controlled fans and pumps shall be sensed by the method indicated in the datasheet.
−# Airflow Measurement Stations {toc}
+```datasheet
+label: Status Sensing - Drive-Controlled Fans and Pumps
+type: radio
+options:
+ - "Current switch on a motor lead"
+ - "Run status from the drive over the network"
+ - "Run status contact from the drive"
+ - "Differential pressure switch across the fan or pump"
+```
−## Airflow measurement stations (AFMS) shall use the selected sensing technology.
+### A current switch proves that the motor is drawing load current, which a broken belt or a sheared coupling removes and an auxiliary contact does not; a differential pressure switch proves that air or water is moving, which a closed damper or valve removes and a current switch does not; a drive's run status proves that the drive is commanding the motor. Each method proves one thing, and the sequence decides which thing the operator needs to know. {note}
+### Current switches shall be split-core, self-powered from the monitored conductor, and rated for the full-load current of the motor served.
+
+### The current switch trip setting shall be as indicated in the datasheet.
+
```datasheet
−label: Airflow Measurement Station Type
+label: Current Switch Trip Setting
type: radio
options:
− - "Pitot-array (flow cross)"
− - "Thermal dispersion"
−default: "Thermal dispersion"
+ - "Adjustable trip set in the field above the no-load current"
+ - "Self-calibrating trip set automatically on first run"
+ - "Fixed trip at the switch's rated threshold"
```
−## A pitot-array (flow-cross) station averages velocity pressure across the duct and is robust and inexpensive, but loses accuracy at very low velocities where velocity pressure becomes negligible. A thermal-dispersion array measures mass flow directly and holds accuracy down to very low velocities, at higher cost, and is preferred for outdoor-air and minimum-ventilation measurement where the flow is small and the accuracy matters most. {note}
+### Current switches on belt-driven or coupled equipment shall have their trip point set above the motor current with the belt removed or the coupling disconnected, and below the motor current at the lowest operating speed.
−## Airflow measurement stations shall be furnished with a factory calibration certificate traceable to the as-built duct configuration.
+### On a drive-controlled motor at minimum speed, the current can fall close to the belt-off current at full speed, and a switch set at startup with the drive at full speed reads off every time the drive slows down. The trip point is set with the drive at minimum speed. {note}
−## Airflow measurement stations shall be installed with the manufacturer's required straight-duct distances upstream and downstream.
+### Motor current sensing shall provide the output indicated in the datasheet.
−## A flow station reads accurately only in a developed, non-swirling velocity profile. Mounting it too close to an elbow, transition, or damper produces a distorted profile and a systematically wrong reading no field calibration can correct. The required straight-run distances are part of the device specification, not a field option. {note}
+```datasheet
+label: Motor Current Sensing Output
+type: radio
+options:
+ - "Status contact"
+ - "Status contact and analog current output"
+ - "Analog current output with a threshold computed at the controller"
+default: "Status contact"
+```
−## Airflow measurement station location shall be coordinated with the ductwork layout to provide the required straight runs. [[drawing: AFMS location and straight-run]]
+## Hydronic Flow Proving {toc}
−# Damper Actuators {toc}
+### Flow through chillers, boilers, heat exchangers, and other equipment whose manufacturer requires proof of flow before operation shall be proven by the device indicated in the datasheet.
−## Damper actuators furnished under this section mount on damper bodies provided under [[sync/louvers-and-dampers]].
+```datasheet
+label: Hydronic Flow Proving Device
+type: select
+options:
+ - "Paddle-type flow switch"
+ - "Thermal dispersion flow switch"
+ - "Differential pressure switch across the equipment"
+ - "Differential pressure transmitter with a threshold at the controller"
+ - "Flow meter output compared with a threshold at the controller"
+```
−## This section covers only the actuator, its control signal, and its fail-safe behavior. The damper blade, frame, seals, and leakage class belong to the damper standard. The two must be coordinated so the actuator torque matches the damper the manufacturer actually ships. {note}
+### A paddle switch responds to velocity at one point and needs a straight run to read; a thermal dispersion switch has no moving part and responds slowly; a differential pressure device across the equipment reads the pressure drop the manufacturer publishes and cannot distinguish low flow from a fouled tube bundle. Where the equipment manufacturer's own controller performs a flow proof, the field device is the backup rather than the interlock. {note}
−## Damper actuator torque shall be sized at a minimum of 2 in-lb per ft² of damper area per AMCA 500-D, with a 20% safety factor added.
+### The flow proving contact shall be hardwired into the equipment safety circuit where the equipment manufacturer requires it, and shall be monitored by the building automation system in every case.
−## The bare-area rule covers the air load, but the torque needed to drive a damper closed also has to overcome blade-seal friction, linkage losses, and the differential pressure across the closed blade. Sizing on area alone is the most common cause of actuators that stall short of full close at design static, which shows up as a TAB failure and a string of RFIs. The submitted torque calculation must account for seal friction and applied safety factor explicitly. {note}
+### Flow switches shall be installed in a straight run of pipe with the upstream and downstream lengths published by the switch manufacturer.
−## Spring-return (fail-safe) actuators shall be furnished on all outside-air, exhaust, and smoke-control dampers.
+### Paddle-type flow switches shall have the paddle trimmed to the pipe size in accordance with the manufacturer's table and shall be set to trip at the minimum flow the equipment manufacturer requires.
−## Damper actuator return type shall be selected for the service.
+## Low-Temperature Limits {toc}
+### Where [[parameter: site-ambient-temperature-minimum]] is below 32°F, a low-temperature limit switch shall be provided on the leaving-air side of each water coil that can receive outdoor air, unless the contract documents indicate another freeze protection method for that coil.
+
+### Low-temperature limit switches shall trip on the coldest point along the element and not on the average temperature of the element.
+
+### A vapor-tension element trips when any short segment falls below the setpoint, which is the property that matters, because a stratified mixing plenum can freeze one corner of a coil while the average across the face is well above freezing. {note}
+
+### Each low-temperature limit element shall serve not more than the coil face area indicated in the datasheet.
+
```datasheet
−label: Damper Actuator Return Type
+label: Maximum Coil Face Area per Low-Temperature Limit Element
+type: range
+unit: ft²
+min: 10
+max: 40
+setpoints: [10, 15, 20, 25, 30, 40]
+default: 20
+```
+
+### The low-temperature limit element length shall be as indicated in the datasheet.
+
+```datasheet
+label: Low-Temperature Limit Element Length
+type: range
+unit: ft
+min: 8
+max: 40
+setpoints: [8, 12, 20, 24, 40]
+derived: "the coil face area and the maximum coil face area served per element"
+default: derived
+```
+
+### Low-temperature limit elements shall be serpentined across the coil face on the leaving-air side, supported on clips, and held clear of the coil fins and the casing.
+
+### Low-temperature limit reset shall be as indicated in the datasheet.
+
+```datasheet
+label: Low-Temperature Limit Reset
type: radio
options:
− - "Spring-return (fail-safe) — required on OA, exhaust, smoke-control"
− - "Non-spring-return (power-driven both directions)"
−default: "Spring-return (fail-safe) — required on OA, exhaust, smoke-control"
+ - "Manual reset at the switch"
+ - "Automatic reset"
+ - "Manual reset from the building automation system"
+default: "Manual reset at the switch"
```
−## Damper actuator control mode shall be selected for the application.
+### The low-temperature limit contact shall be hardwired to stop the supply fan, close the outdoor air damper, and open the coil control valve, in addition to the sequence response programmed at the controller.
+## Condensate Overflow {toc}
+
+### A condensate overflow switch shall be provided in the primary drain pan or the auxiliary drain pan of each cooling coil where the adopted mechanical code requires overflow protection, and at each location indicated on [[drawing: the controls drawings]].
+
+### The condensate overflow switch action shall be as indicated in the datasheet.
+
```datasheet
−label: Damper Actuator Control Mode
+label: Condensate Overflow Switch Action
+type: radio
+options:
+ - "Hardwired to stop the cooling equipment, with the trip reported to the building automation system"
+ - "Hardwired to stop the cooling equipment, not reported"
+ - "Reported to the building automation system, which stops the cooling equipment"
+default: "Hardwired to stop the cooling equipment, with the trip reported to the building automation system"
+```
+
+### The mechanical code's overflow provision is satisfied by a device that shuts the equipment down directly; routing the shutdown through the controller adds the controller and its program to the path the code relies on, which the authority having jurisdiction accepts or does not. {note}
+
+### Condensate overflow switches shall be float or conductance type, mounted so that the trip level is below the pan rim by the margin the switch manufacturer publishes.
+
+### Condensate overflow switches shall be testable by raising the water level in the pan without disassembling the switch.
+
+## Water Leak Detectors {toc}
+
+### Water leak detectors shall be provided at the locations indicated on [[drawing: the controls drawings]].
+
+### Water leak detectors shall be of the type indicated in the datasheet.
+
+```datasheet
+label: Water Leak Detector Type
type: select
options:
− - "Modulating, 2-10 VDC"
− - "Floating (tri-state, 24 VAC)"
− - "On/off (open/close)"
−default: "Modulating, 2-10 VDC"
+ - "Spot detector with floor-contact probes"
+ - "Leak-sensing cable with a zone monitor"
+ - "Leak-sensing cable with a distance-reading monitor"
+ - "Float switch"
```
−## Modulating damper actuators shall use a 2-10 VDC control signal with spring return, not 0-10 VDC.
+### A spot detector reports water at one point and misses a leak that runs the other way; sensing cable reports water anywhere along its run, and a distance-reading monitor says where along the run; a float switch reports a depth of water and suits a pan or a sump rather than a floor. {note}
−## With a 0-10 VDC actuator, a lost or broken signal reads as 0 V, which the actuator interprets as a valid full-open (or full-closed) command rather than a fault. A 2-10 VDC actuator treats 0 V as signal-loss and drives to its spring-return fail-safe position instead. Specifying a 2-10 VDC live-zero signal is what makes signal loss a safe event. {note}
+### Each water leak detector shall report its alarm to the building automation system through a contact or a networked output.
−## Damper actuator torque rating shall be selected to satisfy the calculated requirement.
+### A local audible alarm at each water leak detector shall be provided as indicated in the datasheet.
```datasheet
−label: Damper Actuator Torque Rating
+label: Water Leak Detector Local Audible Alarm
+type: radio
+options:
+ - "Provided"
+ - "Not provided"
+```
+
+### A local sounder brings someone to a leak in a room that is occupied and is heard by no one in a mechanical room that is entered once a week; the alarm at the building automation system reaches the operator in either case. {note}
+
+## Damper and Valve Position Proving {toc}
+
+### Where the sequence requires proof of damper or valve position, position shall be sensed by the device indicated in the datasheet.
+
+```datasheet
+label: Damper and Valve Position Proving Device
+type: radio
+options:
+ - "Auxiliary switch integral to the actuator"
+ - "Blade-mounted end switch on the damper"
+ - "Position feedback signal from the actuator compared with a threshold at the controller"
+default: "Auxiliary switch integral to the actuator"
+```
+
+### An actuator auxiliary switch proves the actuator shaft position, and a blade switch proves the blade; where the linkage between them can slip, only the blade switch proves the damper. {note}
+
+# Occupancy Sensing for HVAC {toc}
+
+## Occupancy Signal Source {toc}
+
+### The source of the occupancy signal used by HVAC zone sequences shall be as indicated in the datasheet.
+
+```datasheet
+label: Occupancy Signal Source for HVAC Zones
type: select
options:
− - "35 in-lb"
− - "70 in-lb"
− - "90 in-lb"
− - "180 in-lb"
− - "300 in-lb"
−default: "70 in-lb"
+ - "Dedicated occupancy sensor wired to the zone controller"
+ - "Occupancy status shared from the lighting control system over the network"
+ - "Occupancy status shared from the lighting occupancy sensor by an isolated contact"
+ - "Occupancy status from the access control or security system"
+ - "Occupant-count sensor at the zone entrance"
+ - "No occupancy sensing, schedule only"
+```
+
+### A shared lighting sensor saves a device in every room and ties the HVAC zone to the lighting sensor's coverage pattern, time delay, and failure; a dedicated sensor costs a device and gives the HVAC sequence its own signal. A networked share depends on both systems' gateways being up; a contact share depends on neither. {note}
+
+### Where the occupancy signal is shared from another system by a contact, the contact shall be isolated so that neither system's control power is connected to the other.
+
+### Where the occupancy signal is shared from another system over the network, the signal shall be presented at the building automation system as a point with the loss-of-communication behavior defined under [[sync/building-automation-system]].
+
+## Dedicated HVAC Occupancy Sensors {toc}
+
+### Dedicated HVAC occupancy sensors shall use the detection technology indicated in the datasheet.
+
+```datasheet
+label: HVAC Occupancy Sensor Detection Technology
+type: select
+options:
+ - "Passive infrared"
+ - "Ultrasonic"
+ - "Dual-technology, passive infrared and ultrasonic"
+ - "Microwave"
+ - "Thermal or optical occupant counting"
+```
+
+### The detection technologies behave as described under [[sync/lighting-controls]]; what differs for HVAC is that a missed occupant puts a zone into setback with someone in it, and a false detection holds a zone at the occupied ventilation rate with no one there. {note}
+
+### Dedicated HVAC occupancy sensors shall provide a voltage-free contact or a networked point to the zone controller.
+
+### The vacancy delay applied by the zone sequence shall be set at the building automation system, and the sensor's own time delay shall be set to its minimum.
+
+### Sensor coverage and mounting shall be as indicated on [[drawing: the controls drawings]].
+
+### Occupancy sensors that also serve lighting control are furnished and governed under [[sync/lighting-controls]]. {note}
+
+# Airflow Measurement Station Hardware {toc}
+
+## The airflow measurement technology, the maximum airflow measurement error, and the straight duct lengths at each station shall be as selected under [[sync/building-automation-system]].
+
+## Airflow measurement station probes shall be of the material indicated in the datasheet.
+
+```datasheet
+label: Airflow Measurement Station Probe Material
+type: radio
+options:
+ - "Aluminum"
+ - "Type 304 stainless steel"
+ - "Type 316 stainless steel"
+default: "Aluminum"
+```
+
+## Aluminum probes cost least and serve a clean airstream for the life of the building; Type 304 stainless steel resists the moisture and the mild chemistry of a laboratory or kitchen exhaust; Type 316 adds the molybdenum that resists chlorides, which is what a coastal outdoor air intake or a pool exhaust carries. {note}
+
+## Stations in kitchen exhaust, laboratory exhaust, or other corrosive or grease-laden airstreams shall be stainless steel, whatever the datasheet selects.
+
+## Each station shall be furnished with a transmitter matched to its probe array by the station manufacturer, delivering the output selected under Transmitter Output Signal.
+
+## Where a factory calibration certificate is required under Testing, the certificate for each station shall state the calibration airflow range and the probe configuration tested.
+
+## Thermal dispersion stations installed where the airstream carries fog, snow, or entrained moisture shall be furnished with the moisture protection the station manufacturer publishes for that exposure.
+
+# Damper Actuators {toc}
+
+## Damper Actuator Sizing and Mounting {toc}
+
+### The control signal, the fail-safe mechanism for each damper class, and the torque margin above close-off torque shall be as selected under [[sync/building-automation-system]].
+
+### The torque rating of each damper actuator shall be as indicated in the datasheet.
+
+```datasheet
+label: Damper Actuator Torque Rating
+type: range
unit: in-lb
+min: 18
+max: 360
+setpoints: [18, 35, 45, 70, 90, 135, 180, 270, 360]
+derived: "the damper manufacturer's published close-off torque at the maximum differential pressure across the damper, increased by the torque margin selected under the building automation system standard"
+default: derived
```
−## Damper actuator fail-safe position on loss of power shall match the sequence of operations. [[drawing: damper fail-safe position schedule]]
+### Damper close-off torque is published by the damper manufacturer from testing under ANSI/AMCA 500-D and rises with blade seal friction and differential pressure, which is why the calculation starts from the damper the project actually buys under [[sync/louvers-and-dampers]] rather than from a torque-per-area rule. {note}
−# Valve Actuators {toc}
+### Where the required torque exceeds the rating of one actuator, two or more actuators of the same model shall be mounted on a jackshaft and driven by the same signal.
−## Electric valve actuators for hydronic two-way and three-way control valves shall be furnished under this section.
+### Damper actuators shall be mounted as indicated in the datasheet.
−## The valve body and trim are part of the hydronic system; this section covers the electric actuator that drives it, its control signal, and its fail-safe direction. Industrial process control valves and positioners are not covered here and are governed by [[sync/control-valves-and-actuators]]. {note}
+```datasheet
+label: Damper Actuator Mounting
+type: radio
+options:
+ - "Direct-coupled to the damper shaft"
+ - "Crank arm and linkage"
+ - "Direct-coupled to a jackshaft"
+default: "Direct-coupled to the damper shaft"
+```
−## Valve actuators shall be electric type with a 24 VAC/VDC supply, unless an existing pneumatic system is being retained.
+### A direct-coupled actuator clamps to the shaft and has no linkage to slip, wear, or be adjusted; a crank arm and linkage fits an actuator where the shaft end is inaccessible and adds two pivots and a rod whose adjustment sets the stroke. {note}
+### Actuators shall be protected against overload throughout the stroke by electronic stall detection and shall not depend on end switches to stop the motor at the end positions.
+
+### Actuators shall provide a means of limiting the stroke at each end without changing the control signal range.
+
+### Non-spring-return damper actuators shall provide a manual gear release or crank so that the damper can be positioned without power.
+
+### Modulating damper actuators shall be rated for continuous modulating duty.
+
+### Actuators for fire, smoke, and combination dampers are furnished with the damper as part of its listing under [[sync/fire-and-smoke-dampers]]; the connection of those actuators and their status contacts to the field controller is made under this standard. {note}
+
+## Damper Actuator Features {toc}
+
+### Actuators on outdoor air, relief, and isolation dampers shall be furnished with the number of auxiliary switches indicated in the datasheet.
+
```datasheet
−label: Valve Actuator Type
+label: Auxiliary Switches - Outdoor Air, Relief, and Isolation Damper Actuators
+type: range
+unit: switches
+min: 0
+max: 2
+setpoints: [0, 1, 2]
+default: 1
+```
+
+### Actuators on other modulating dampers shall be furnished with the number of auxiliary switches indicated in the datasheet.
+
+```datasheet
+label: Auxiliary Switches - Other Modulating Damper Actuators
+type: range
+unit: switches
+min: 0
+max: 2
+setpoints: [0, 1, 2]
+default: 0
+```
+
+### Auxiliary switches shall be adjustable over the full stroke and rated for the circuit they switch.
+
+### Modulating damper actuators shall provide position feedback as indicated in the datasheet.
+
+```datasheet
+label: Damper Actuator Position Feedback
type: radio
options:
− - "Electric, modulating"
− - "Electric, on/off"
− - "Pneumatic (existing pneumatic system retained)"
−default: "Electric, modulating"
+ - "No position feedback"
+ - "Analog position feedback signal to the controller"
+ - "Position reported over the field bus"
+default: "No position feedback"
```
−## Modulating valve actuators shall accept a 2-10 VDC control signal.
+### Position feedback closes the loop on the actuator rather than on the damper; it detects a stalled or disconnected actuator and does not detect a slipped linkage or a blade that does not follow the shaft. {note}
−## Valve actuators shall be rated for at least 1.25 times the valve close-off differential pressure.
+### The maximum running time of modulating damper actuators for the full stroke shall be as indicated in the datasheet.
−## An actuator that can position the valve mid-stroke but cannot drive it fully closed against system differential pressure leaks flow at the closed position, defeating temperature control and wasting energy. Sizing for 1.25 times the close-off pressure gives margin for pump head variation and valve wear. {note}
+```datasheet
+label: Maximum Running Time - Modulating Damper Actuators
+type: range
+unit: seconds
+min: 15
+max: 300
+setpoints: [15, 30, 60, 90, 120, 150, 300]
+```
−## Valve actuator fail-safe position on loss of power shall be coordinated with the coil it serves and matched to the actuator's spring-return direction at the time of purchase.
+### A fast actuator lets the loop respond to a disturbance sooner and lets an oscillating loop oscillate faster; an actuator that takes two minutes to stroke limits how quickly a poorly tuned loop can hunt, which is not the same as tuning it. Smoke control and pressurization sequences set their own closure times under [[sync/smoke-control-systems]]. {note}
−## Fail direction is a life-and-property decision, not a default. A chilled-water coil valve should fail closed so a power loss cannot flood the coil and the space below it. A hot-water or steam coil in a freeze-prone air stream may need to fail open to keep flow through the coil and prevent a freeze burst. The spring-return direction is fixed when the actuator is bought, so the failure mode must be settled before procurement, not at startup. {note}
+# Automatic Control Valves {toc}
−## Valve actuator fail-safe position shall be selected per the served coil.
+## Control Valve Configuration {toc}
+### This section covers the two-way and three-way control valves that the building automation system modulates or positions on hydronic coils, heat exchangers, and steam coils. The actuator's control signal, fail-safe mechanism, and close-off basis are selected under [[sync/building-automation-system]], and the actuator itself is furnished under Valve Actuators. {note}
+
+### Pressure-independent control valves are furnished as a hydronic specialty complete with their actuator under [[sync/hydronic-specialties]] and are not selected here. {note}
+
+### The configuration of each control valve as two-way, three-way mixing, or three-way diverting shall be as indicated on [[drawing: the mechanical drawings]].
+
+## Control Valve Body Type {toc}
+
+### The body type of control valves NPS 2 and smaller shall be as indicated in the datasheet.
+
```datasheet
−label: Valve Actuator Fail-Safe Position
+label: Control Valve Body Type - NPS 2 and Smaller
type: select
options:
− - "Fail closed (chilled-water coils)"
− - "Fail open (hot-water/steam coils in freeze-prone air streams)"
− - "Fail last (modulating, no freeze or flood risk)"
−default: "Fail closed (chilled-water coils)"
+ - "Characterized ball valve"
+ - "Globe valve"
+ - "Two-position zone valve"
+ - "Six-way characterized ball valve for four-pipe changeover"
```
−# Network Integration {toc}
+### The body type of control valves NPS 2-1/2 and larger shall be as indicated in the datasheet.
−## Networked field devices shall communicate over the project's BAS network protocol per ANSI/ASHRAE 135.
+```datasheet
+label: Control Valve Body Type - NPS 2-1/2 and Larger
+type: select
+options:
+ - "Flanged globe valve"
+ - "Flanged characterized ball valve"
+ - "High-performance double-offset butterfly valve"
+ - "Resilient-seated butterfly valve"
+```
−## BACnet MS/TP and BACnet/IP are the dominant building-controls protocols; Modbus RTU appears on some packaged equipment. The network architecture, addressing, and controller-side integration are owned by [[sync/building-automation-system]]; this section requires only that the field device speak the protocol the project has standardized on. {note}
+### A globe valve throttles smoothly over its full stroke and is repairable in the line; a characterized ball valve reaches the same flow coefficient in a smaller, lower-cost body and closes tighter; a resilient-seated butterfly valve throttles usefully over only part of its rotation, which is why it is most often applied to two-position isolation of chillers, towers, and boilers rather than to a modulating coil. {note}
−## Networked field device protocol shall be selected to match the BAS network.
+## Control Valve Flow Characteristic {toc}
+### The inherent flow characteristic of two-way coil control valves shall be as indicated in the datasheet.
+
```datasheet
−label: Networked Device Protocol
+label: Inherent Flow Characteristic - Two-Way Coil Control Valves
+type: radio
+options:
+ - "Equal percentage"
+ - "Linear"
+ - "Modified parabolic"
+default: "Equal percentage"
+```
+
+### Three-way valves shall combine the characteristic selected for the coil port with a linear characteristic in the bypass port.
+
+### A water coil delivers most of its capacity at a small fraction of design flow, so its output rises steeply at low flow and flattens near design. An equal percentage valve opens slowly at first and faster later, which offsets that curve and gives the loop a nearly proportional relation between valve position and heat delivered; a linear characteristic suits a service whose output is already proportional to flow, such as a heat exchanger held at a small approach. {note}
+
+## Control Valve Sizing {toc}
+
+### The flow coefficient of each control valve shall be calculated in accordance with ANSI/ISA-75.01.01 for the design flow and design pressure drop of its service.
+
+### Each modulating hydronic control valve shall be selected so that its pressure drop at design flow, divided by the sum of that pressure drop and the pressure drop of the circuit whose flow it varies, is not less than the valve authority indicated in the datasheet.
+
+```datasheet
+label: Minimum Valve Authority - Modulating Hydronic Valves
+type: range
+unit: ratio
+min: 0.1
+max: 0.8
+setpoints: [0.1, 0.2, 0.25, 0.3, 0.4, 0.5, 0.6, 0.8]
+```
+
+### The pressure drop of each modulating hydronic control valve at design flow shall not exceed the value indicated in the datasheet.
+
+```datasheet
+label: Maximum Pressure Drop at Design Flow - Modulating Hydronic Valves
+type: range
+unit: psi
+min: 1
+max: 15
+setpoints: [1, 2, 3, 4, 5, 6, 8, 10, 15]
+```
+
+### Low authority lets the rest of the circuit take over the pressure drop as the valve closes, so the valve does most of its throttling in the last few percent of its stroke; raising authority buys control at the cost of pump head, which is why the minimum authority and the maximum pressure drop are set as a pair. {note}
+
+### Each modulating steam control valve shall be sized for the design steam flow at the pressure drop indicated in the datasheet, expressed as a percentage of the valve inlet gauge pressure.
+
+```datasheet
+label: Steam Control Valve Design Pressure Drop
+type: range
+unit: '% of inlet gauge pressure'
+min: 10
+max: 80
+setpoints: [10, 20, 30, 40, 50, 60, 70, 80]
+```
+
+### A larger share of the inlet pressure taken across the steam valve gives it authority over the coil and its trap; past the critical pressure ratio, roughly half the absolute inlet pressure, the flow no longer rises with the drop while the noise and the trim wear still do. {note}
+
+### Two-position control valves shall be line size unless otherwise indicated on [[drawing: the mechanical drawings]].
+
+### A control valve smaller than the line in which it is installed shall be connected with concentric reducers.
+
+## Control Valve Construction {toc}
+
+### Control valve bodies shall carry a manufacturer's published pressure-temperature rating, under ASME B16.34 or the valve standard applicable to the body material, of not less than the working pressure indicated in the datasheet at the maximum design temperature of the service.
+
+```datasheet
+label: Minimum Control Valve Body Working Pressure Rating
+type: range
+unit: psig
+min: 125
+max: 600
+setpoints: [125, 150, 200, 250, 300, 400, 600]
+derived: "the design working pressure and maximum design temperature of the piping system served, as specified in the piping standard for that service"
+default: derived
+```
+
+### The body material of control valves NPS 2 and smaller shall be as indicated in the datasheet.
+
+```datasheet
+label: Control Valve Body Material - NPS 2 and Smaller
type: select
options:
− - "BACnet MS/TP"
− - "BACnet/IP"
− - "Modbus RTU"
−default: "BACnet MS/TP"
+ - "Forged brass"
+ - "Cast bronze"
+ - "Stainless steel"
```
−## Wireless field sensors shall be used only where a wired run is impractical.
+### The body material of control valves NPS 2-1/2 and larger shall be as indicated in the datasheet.
−## Wireless field sensors shall provide a minimum 5-year battery life.
+```datasheet
+label: Control Valve Body Material - NPS 2-1/2 and Larger
+type: select
+options:
+ - "Cast iron"
+ - "Ductile iron"
+ - "Carbon steel"
+ - "Stainless steel"
+```
−## Wireless mesh sensors are a retrofit tool for places a wire cannot reasonably reach, not a default. ASHRAE Guideline 13 sets a 5-year minimum battery life so a ceiling full of sensors does not become an annual ladder-and-battery maintenance burden. Mechanical rooms are RF-hostile and may need wired repeaters that must be accounted for in the BAS scope, not discovered at startup. {note}
+### Brass and bronze bodies match copper tube and the pressure classes of small coils; stainless steel is chosen where the fluid attacks copper alloys, as high-concentration glycol, deionized water, and some treatment chemistries do. At larger sizes, cast iron costs least within its pressure and temperature limits, ductile iron extends both, and carbon steel is the body where the piping standard sets a rating that iron cannot meet. {note}
−## Wireless sensor battery replacement access shall be provided without removing finished ceiling or equipment.
+### The ball and stem material of characterized ball valves shall be as indicated in the datasheet.
```datasheet
−label: Field Sensor Wiring Method
+label: Characterized Ball Valve Ball and Stem Material
type: radio
options:
− - "Wired"
− - "Wireless mesh (retrofit, ≥5-year battery, wire run impractical)"
−default: "Wired"
+ - "300-series stainless steel"
+ - "Chrome-plated brass"
+ - "Nickel-plated brass"
```
+### A stainless ball and stem resist the dezincification and plating wear that plated brass shows in glycol and in water with a high chloride content; the plated options cost less and hold up where the water treatment under [[sync/hvac-water-treatment]] is maintained. {note}
+
+### The seat leakage of two-way control valves shall not exceed the ANSI/FCI 70-2 class indicated in the datasheet.
+
+```datasheet
+label: Maximum Seat Leakage Class - Two-Way Control Valves
+type: select
+options:
+ - "ANSI/FCI 70-2 Class II"
+ - "ANSI/FCI 70-2 Class III"
+ - "ANSI/FCI 70-2 Class IV"
+ - "ANSI/FCI 70-2 Class V"
+ - "ANSI/FCI 70-2 Class VI"
+```
+
+### Class IV is the customary rating of a metal-seated globe valve; Class VI is bubble-tight and is reached with a soft seat that wears faster at high differential pressure and high temperature. The tighter class matters on a heating coil that must not creep in summer, and matters not at all on a coil that is never fully closed. {note}
+
+### Stem packing on control valves NPS 2-1/2 and larger shall be replaceable without removing the valve from the piping.
+
+## Control Valve End Connections {toc}
+
+### End connections of control valves NPS 2 and smaller shall be compatible with the joining method of the adjacent piping.
+
+```datasheet
+label: Control Valve End Connections - NPS 2 and Smaller
+type: select
+options:
+ - "Threaded, NPT"
+ - "Press-connect for copper tube"
+ - "Solder end"
+ - "Union end"
+derived: "the joining method of the adjacent piping at each valve"
+default: derived
+```
+
+### End connections of control valves NPS 2-1/2 and larger shall be compatible with the joining method of the adjacent piping.
+
+```datasheet
+label: Control Valve End Connections - NPS 2-1/2 and Larger
+type: select
+options:
+ - "Flanged"
+ - "Grooved"
+ - "Lug-style"
+ - "Wafer-style"
+derived: "the joining method of the adjacent piping at each valve"
+default: derived
+```
+
+### The end connection follows the joining method the piping trade uses at that size under [[sync/hydronic-piping]] and [[sync/chilled-and-condenser-water-piping]], which is why both fields are derived rather than chosen here; a lug body can be removed with the downstream pipe in place and a wafer body cannot, which is the one difference a bidder decides on for an isolation service. {note}
+
+# Valve Actuators {toc}
+
+## Valve Actuator Selection {toc}
+
+### The control signal, the fail-safe mechanism for each valve class, and the close-off basis shall be as selected under [[sync/building-automation-system]].
+
+### Control valve bodies are furnished under Automatic Control Valves; this section furnishes the actuator that drives them. {note}
+
+### Valve actuators shall be of the motive type indicated in the datasheet.
+
+```datasheet
+label: Valve Actuator Motive Type
+type: radio
+options:
+ - "Electric motor actuator"
+ - "Electro-hydraulic actuator"
+ - "Pneumatic actuator"
+default: "Electric motor actuator"
+```
+
+### An electro-hydraulic actuator develops high close-off force at a slow, steady stroke and suits a large globe valve at high differential pressure; a pneumatic actuator is chosen where an existing compressed air system is retained or where the plant already maintains instrument air. {note}
+
+### Pneumatic valve actuators shall be selected only where the pneumatic control device policy under Pneumatic Control Devices permits them, and shall comply with that section.
+
+### Actuators for stem-lift valves shall be linear, and actuators for quarter-turn valves shall be rotary, each coupled to the valve without an intermediate linkage.
+
+### The close-off differential pressure rating of each valve actuator shall be as indicated in the datasheet.
+
+```datasheet
+label: Valve Actuator Close-Off Rating
+type: range
+unit: psi
+min: 25
+max: 300
+setpoints: [25, 50, 75, 100, 150, 200, 300]
+derived: "the maximum differential pressure the pumping system can develop at the valve with all other valves closed, as required under the building automation system standard"
+default: derived
+```
+
+### Valve and actuator assembly shall be as indicated in the datasheet.
+
+```datasheet
+label: Valve and Actuator Assembly
+type: radio
+options:
+ - "Actuator factory-mounted on the valve and tested as one assembly"
+ - "Actuator field-mounted on the valve by the controls contractor"
+default: "Actuator factory-mounted on the valve and tested as one assembly"
+```
+
+### A factory-mounted assembly arrives with the stroke set and the close-off verified under one warranty for the pair; field mounting lets the piping trade set the valve early and the controls trade mount the actuator later, and puts the stroke setting and the warranty boundary between two trades. {note}
+
+## Valve Actuator Features {toc}
+
+### Modulating valve actuators shall provide position feedback as indicated in the datasheet.
+
+```datasheet
+label: Valve Actuator Position Feedback
+type: radio
+options:
+ - "No position feedback"
+ - "Analog position feedback signal to the controller"
+ - "Position reported over the field bus"
+default: "No position feedback"
+```
+
+### The maximum running time of modulating valve actuators for the full stroke shall be as indicated in the datasheet.
+
+```datasheet
+label: Maximum Running Time - Modulating Valve Actuators
+type: range
+unit: seconds
+min: 15
+max: 300
+setpoints: [15, 30, 60, 90, 120, 150, 300]
+```
+
+### Non-spring-return valve actuators shall provide a manual override so that the valve can be positioned without power.
+
+### Valve actuators mounted where the valve stem can fall below the dew point of the surrounding air shall be furnished with a stem heater or a thermal barrier between the valve and the actuator.
+
+### A chilled water valve stem in a humid mechanical room condenses continuously, and the condensate runs into the actuator housing, which is the usual cause of an actuator that fails in its second summer. {note}
+
+### Valve actuators shall be rated for continuous modulating duty and shall be electronically protected against overload at the end positions.
+
+## Terminal Unit Valve Actuators {toc}
+
+### Actuators on terminal unit coil valves shall be of the type indicated in the datasheet.
+
+```datasheet
+label: Terminal Unit Valve Actuator Type
+type: radio
+options:
+ - "Modulating electric actuator"
+ - "Floating electric actuator"
+ - "Two-position electric actuator"
+ - "Two-position thermal actuator"
+```
+
+### A thermal actuator moves a wax element with a heater and has no motor, no gear train, and no audible operation; it takes minutes to stroke and cannot modulate. A floating actuator modulates without position feedback and drifts from its commanded position unless the sequence periodically drives it to an end stop. {note}
+
+# Pneumatic Control Devices {toc}
+
+## Pneumatic Device Policy {toc}
+
+### Pneumatic control devices shall be used only as permitted by the policy indicated in the datasheet.
+
+```datasheet
+label: Pneumatic Control Device Policy
+type: radio
+options:
+ - "No pneumatic control devices"
+ - "Extension of an existing pneumatic control system"
+ - "Pneumatic actuators under electronic control through electro-pneumatic transducers"
+default: "No pneumatic control devices"
+```
+
+### A pneumatic actuator needs control air that is compressed, dried, filtered, and kept that way; where the plant already maintains that supply for an existing system, extending it costs less than replacing every actuator it serves, and where it does not, the compressor and the dryer are the price of the first pneumatic device. {note}
+
+### Requirements in this section apply where the policy permits pneumatic control devices.
+
+### The compressor, dryer, receiver, and main distribution that produce and deliver control air are furnished under [[sync/compressed-air-systems]]; this section begins at the branch that serves a control device. {note}
+
+### Where the policy permits extension of an existing pneumatic control system, the Contractor shall verify before connecting to it that the existing control air supply meets ANSI/ISA-7.0.01 and has the capacity to serve the added devices.
+
+### The Contractor shall report any deficiency found in the existing control air supply to the Engineer in writing before connecting to it.
+
+## Electro-Pneumatic Transducers {toc}
+
+### Electro-pneumatic transducers shall convert the controller output to a pneumatic output whose span matches the spring range of the actuators they serve.
+
+### Each electro-pneumatic transducer shall be furnished with an output pressure gauge.
+
+### Electro-pneumatic transducers shall be mounted in a controller panel or in an enclosure outside the air stream.
+
+## Pneumatic Actuators and Positioners {toc}
+
+### Pneumatic actuators sequenced with another actuator on a common signal shall be fitted with a positive positioner.
+
+### The spring ranges of pneumatic actuators sequenced on a common signal shall not overlap unless the sequence of operations requires overlapping operation.
+
+### The spring range stamped on an actuator is its range at no load; friction and the force of the air or the water on the blade or plug shift the range in service, so two actuators sequenced on their nameplate ranges drift into overlap and open together. A positioner holds each actuator to its commanded position against that load. {note}
+
+## Control Air Quality {toc}
+
+### Control air delivered to pneumatic devices shall meet the particulate, oil content, and pressure dew point requirements of ANSI/ISA-7.0.01.
+
+### The pressure dew point of control air serving tubing routed outdoors or through unheated spaces shall be below [[parameter: site-ambient-temperature-minimum]].
+
+## Control Air Tubing {toc}
+
+### Control air tubing shall be of the material indicated in the datasheet.
+
+```datasheet
+label: Control Air Tubing Material
+type: select
+options:
+ - "Type L copper tube"
+ - "Polyethylene tubing in metallic raceway"
+ - "Fire-retardant polyethylene tubing listed for air-handling spaces"
+```
+
+### Copper tube resists heat and crushing and needs no raceway for a plenum; polyethylene in raceway costs less per foot and depends on the raceway for both its protection and its plenum listing; listed fire-retardant polyethylene runs exposed in a plenum and is the least tolerant of a tight bend or a dropped tool. {note}
+
+### Tubing installed in a plenum used for environmental air shall be copper or shall be listed for that use in accordance with NFPA 90A.
+
+### Control air tubing shall be pressure tested at not less than 1.5 times its maximum operating pressure for the duration indicated in the datasheet.
+
+```datasheet
+label: Control Air Tubing Pressure Test Duration
+type: range
+unit: minutes
+min: 15
+max: 240
+setpoints: [15, 30, 60, 120, 240]
+```
+
+### Control air tubing shall show no pressure loss readable on a test gauge graduated in increments of 1 psi or finer over the test duration.
+
# Installation {toc}
−## Devices shall be installed in accordance with the manufacturer's published instructions and the approved shop drawings.
+## Device Mounting {toc}
−## Sensor and actuator locations shall be coordinated with [[sync/mechanical-insulation]] so that pipe-mounted sensors and flow stations are excluded from the insulation scope or provided with serviceable insulation jackets.
+### Devices shall be installed in accordance with the manufacturer's published instructions and the reviewed mounting details.
−## A pipe temperature tap or flow station buried under continuous insulation is unreadable and unserviceable. Coordinating the insulation scope at submittal keeps the sensing points accessible and the insulation continuous everywhere else. {note}
+### Each device shall be mounted so that it can be removed and replaced without disturbing ductwork, piping, insulation, or another device, and the access doors required for that purpose shall be coordinated under [[sync/duct-accessories]].
−## Wiring terminations shall be made to the field controller per the approved wiring diagrams and classified per NFPA 70 Article 725.
+### Pipe-mounted sensors, thermowells, flow switches, and pressure taps shall be coordinated with [[sync/mechanical-insulation]] so that each is left accessible and the insulation is finished around it.
−## Immersion sensors shall be installed with the element tip in the flowing stream and the thermowell oriented against the flow where required by the manufacturer.
+### Outdoor devices shall be mounted with the conduit entering from below and with a drip loop in any cable entering the enclosure.
−## Outdoor sensors shall be installed in their radiation shields, away from exhaust discharges, condensing-unit airflow, and wall-reflected solar load.
+### Devices shall not be mounted on removable panels, access doors, or filter access frames of equipment.
−## Each installed device shall be labeled with its ISA-5.1 tag number matching the device schedule.
+## Control Valve Installation {toc}
+### Control valves shall be installed with the actuator above the horizontal centerline of the pipe.
+
+### Control valves shall be installed with the body flow arrow matching the direction of flow.
+
+### Control valves NPS 2 and smaller shall be installed with unions or flanged connections that allow removal of the valve without cutting pipe.
+
+## Wiring and Termination {toc}
+
+### Field device wiring, separation, shielding of network cable, and termination shall comply with [[sync/building-automation-system]].
+
+### Shielded cable serving an analog transmitter shall have its shield grounded at the controller panel only, and the shield at the device shall be insulated from the device housing.
+
# Testing {toc}
−## Each device shall be point-to-point verified from the sensing element or actuator to the controller input/output before TAB and commissioning.
+## Factory Calibration Certificates {toc}
−## Point-to-point verification confirms that the device wired to a given controller terminal is the device the drawings say is there and that it reads or strokes correctly. It is a device-level check; integrated functional performance testing of the assembled system is owned by [[sync/commissioning]], and instrument-calibrated flow measurement is owned by [[sync/testing-adjusting-and-balancing]]. {note}
+### Factory calibration certificates traceable to a national metrology institute shall be furnished for the device classes indicated in the datasheet.
−## Each sensor shall be field-calibrated against a reference instrument and verified to within 1.5 times its rated accuracy.
+```datasheet
+label: Device Classes Requiring Factory Calibration Certificates
+type: checkbox
+options:
+ - "Carbon dioxide sensors"
+ - "Humidity sensors"
+ - "Differential pressure transmitters"
+ - "Airflow measurement stations"
+ - "Temperature transmitters"
+ - "Outdoor air temperature sensors"
+ - "Space temperature sensors"
+ - "Electro-pneumatic transducers"
+default:
+ - "Carbon dioxide sensors"
+ - "Humidity sensors"
+ - "Differential pressure transmitters"
+ - "Airflow measurement stations"
+```
−## Each modulating actuator shall be stroked through its full range and verified to reach commanded position at 0%, 50%, and 100%.
+### A factory certificate records the device as it left the bench; it does not survive a drop in shipping or a month on a dusty site. It establishes the baseline against which the field verification is judged, and a device whose field reading disagrees with its certificate by more than the specified error is the one to return rather than adjust. {note}
−## Each spring-return actuator shall be verified to drive to its fail-safe position on loss of power and loss of signal.
+## Field Verification {toc}
−## A signed field calibration and verification report shall be submitted for every device before TAB begins.
+### Sensor calibration against a reference instrument, the disposition of sensors that fail it, and the calibration record shall be as required under [[sync/building-automation-system]].
+### Each actuator shall be commanded to 0%, 50%, and 100% of its signal range, and the damper or valve position observed at each point shall be recorded.
+
+### Each spring-return and stored-energy fail-safe actuator shall be verified to reach its fail-safe position on loss of control power and, separately, on loss of control signal with power maintained.
+
+### Each current switch shall be verified to indicate off with the belt removed or the coupling disconnected, and to indicate on with the equipment at its lowest operating speed.
+
+### Each pressure switch shall have its trip point verified with a calibrated pressure source rather than by driving the system to the trip condition.
+
+### Each low-temperature limit switch shall be verified to trip by cooling a section of the element below the setpoint, and to interrupt the circuits it serves.
+
+### Each condensate overflow switch shall be verified to trip by raising the water level in the pan, and to stop the equipment it serves.
+
+### Each flow proving device shall be verified to indicate no flow with the isolation valve closed and flow with the pump running.
+
+### Each water leak detector shall be verified to alarm at the building automation system by wetting its probes, or a point along each run of sensing cable.
+
+### Before the piping is insulated, each control valve shall be inspected for flow direction and port orientation against the control valve schedule.
+
+### Each wireless sensor's received signal strength at its gateway or parent node shall be recorded, and any sensor below the manufacturer's minimum margin shall be relocated or served by an added repeater before acceptance.
+
+### Each switch's as-left trip setting shall be recorded on the status and safety switch setpoint record.
+
+### Device-level tests shall be completed and recorded before the point-to-point verification and field functional testing required under [[sync/building-automation-system]] begin.
+
+### The allocation of repeat-test cost after a failed test shall be as required under [[sync/building-automation-system]].
+
# Delivery, Storage, and Handling {toc}
−## Devices shall be delivered in the manufacturer's original packaging with calibration certificates enclosed.
+## Devices shall be delivered in the manufacturer's original packaging with calibration certificates and installation instructions enclosed.
−## Devices shall be stored indoors in a clean, dry, temperature-controlled environment until installation.
+## Devices shall be stored indoors in a clean, dry location within the storage temperature range published by the manufacturer.
−## CO2 and humidity sensors shall be protected from construction dust.
+## Carbon dioxide, humidity, and air quality sensors shall remain sealed in their packaging until dust-producing work in the space where they are installed is complete.
−## CO2 and humidity sensors shall not be energized or exposed during dusty construction activities.
+## Where a carbon dioxide, humidity, or air quality sensor must be installed before dust-producing work is complete, it shall be covered with a dust-tight cover that is removed only after final cleaning, and the installation date and the uncovering date shall be recorded in the device schedule.
−## Construction dust coats optical CO2 windows and contaminates humidity elements, shifting calibration before the device ever sees service. Keeping these sensors sealed until the space is clean preserves the factory calibration the project paid for. {note}
+## Construction dust coats the optical window of an infrared sensor and lodges in the pores of a humidity element, and the shift it causes does not appear until the reading is compared with a reference. {note}
+## Control valves, thermowells, flow switch tees, and pressure taps shall be delivered to the piping installer before the section they serve is closed and pressure tested.
+
# Warranty {toc}
−## Devices shall be warranted against defects in materials and workmanship for a minimum of one year from substantial completion.
+## Field devices shall be warranted against defects in materials and workmanship for the period indicated in the datasheet, measured from the date of substantial completion.
−## CO2 sensors shall carry a manufacturer's calibration-stability warranty of not less than five years.
+```datasheet
+label: Field Device Warranty Period
+type: range
+unit: years
+min: 1
+max: 5
+setpoints: [1, 2, 3, 5]
+default: 1
+```
−## A long calibration-stability warranty is the manufacturer's commitment that the device will not drift out of tolerance over its service life, which is the property that actually matters for a DCV sensor. A one-year defects warranty says nothing about drift. {note}
+## Where field devices are furnished under the same contract as the building automation system, warranty coverage, repair, and response for the devices shall be as required under [[sync/building-automation-system]].
+## Carbon dioxide sensors shall be warranted to remain within their specified measurement error without field recalibration for the period indicated in the datasheet.
+
+```datasheet
+label: Carbon Dioxide Sensor Calibration Warranty Period
+type: range
+unit: years
+min: 1
+max: 15
+setpoints: [1, 2, 3, 5, 7, 10, 15]
+default: 5
+```
+
+## A defects warranty covers a sensor that stops working; a calibration warranty covers one that keeps working and reads wrong, which for a demand-controlled ventilation sensor is the failure that costs energy or ventilation. {note}
+
+## Where a device is repaired or replaced under warranty, the repaired or replaced device shall carry a new warranty of the same term from the date of the repair, or the remainder of the original term, whichever ends later.
+
# Spare Parts {toc}
−## The Contractor shall furnish the following spare parts and consumables:
−- Two of each space temperature sensor type installed.
−- One of each transmitter type installed.
−- Replacement CO2 sensor elements or modules where the sensor uses a field-replaceable element, in the quantity scheduled.
+## Spare sensors and actuators of the classes listed under [[sync/building-automation-system]] shall be furnished as required there.
+## The Contractor shall deliver the additional spare devices indicated in the datasheet at substantial completion.
+
```datasheet
−label: Spare Parts Furnished
+label: Additional Spare Devices Delivered at Substantial Completion
type: checkbox
options:
− - Space temperature sensors (2 of each type)
− - Transmitters (1 of each type)
− - Replaceable CO2 elements/modules (as scheduled)
+ - "Thermostats of each model installed"
+ - "Current switches of each model installed"
+ - "Low-temperature limit switches of each model installed"
+ - "Differential pressure switches of each model installed"
+ - "Condensate overflow switches of each model installed"
+ - "Water leak detectors of each type installed"
+ - "Carbon dioxide sensing modules of each model installed"
+ - "Humidity sensing elements of each model installed"
+ - "One full replacement set of wireless sensor batteries"
+ - "Actuator auxiliary switch kits of each model installed"
+ - "Thermowells of each size installed"
+ - "Stem packing kits for each control valve model NPS 2-1/2 and larger"
+ - "Electro-pneumatic transducers of each model installed"
default:
− - Space temperature sensors (2 of each type)
− - Transmitters (1 of each type)
+ - "Current switches of each model installed"
+ - "One full replacement set of wireless sensor batteries"
```
+
+## Spare devices of each selected class shall be furnished in the quantity indicated in the datasheet.
+
+```datasheet
+label: Spare Device Quantity per Class
+type: range
+unit: units
+min: 1
+max: 10
+setpoints: [1, 2, 3, 5, 10]
+default: 2
+```
+
+## Spare devices shall match the installed devices in model, range, and firmware, and shall be turned over against a written inventory signed by the Owner's representative.
+
+## Spare sensors with polymer humidity elements or infrared optics age in storage, and a spare kept for five years can be no better than the device it replaces; the inventory records the delivery date so the Owner can rotate them. {note}