Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Hydronic Specialties
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# Environmental and Service Conditions {toc}
−## Hydronic specialties operate continuously in a wetted, often glycol-bearing environment across a wide temperature band; material selection and pressure class must be matched to the actual service fluid and operating envelope, not to a generic rating. {note}
+## Hydronic specialties operate continuously in a wetted, often glycol-bearing environment across a wide temperature band; material selection and pressure class must be matched to the actual service fluid and operating envelope, not to a generic rating.
## System design pressure and temperature shall be established for each circuit and used as the selection basis for every specialty in that circuit.
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## Device family selection {toc}
−### The hydronic distribution shall use one of three flow control device families at each branch and terminal: manual calibrated balancing valves, automatic flow-limiting (pressure-independent balancing) valves, or pressure-independent control valves. {note}
+### The hydronic distribution shall use one of three flow control device families at each branch and terminal: manual calibrated balancing valves, automatic flow-limiting (pressure-independent balancing) valves, or pressure-independent control valves.
−### On variable-flow systems pursuing ANSI/ASHRAE/IES 90.1 balancing compliance, the flow control device shall maintain design flow at part-load operating conditions.
−
−### Fixed-orifice manual balancing valves shall not be specified as the sole balancing device on variable-primary systems where part-load flow stability is required for 90.1 compliance.
−
−#### On a variable-primary system, manually set fixed-orifice circuit setters are balanced at one operating point only; as other branches modulate, the differential pressure across each setter shifts and the flow drifts. Automatic flow-limiting valves or PICVs hold flow across a differential pressure band and are the compliant choice where part-load stability is required. {note}
−
```datasheet
label: Flow Control Device Family
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```
+### On variable-flow systems pursuing ANSI/ASHRAE/IES 90.1 balancing compliance, the flow control device shall maintain design flow at part-load operating conditions.
+
+### Fixed-orifice manual balancing valves shall not be specified as the sole balancing device on variable-primary systems where part-load flow stability is required for 90.1 compliance.
+
+#### On a variable-primary system, manually set fixed-orifice circuit setters are balanced at one operating point only; as other branches modulate, the differential pressure across each setter shifts and the flow drifts. Automatic flow-limiting valves or PICVs hold flow across a differential pressure band and are the compliant choice where part-load stability is required. {note}
+
## Manual calibrated balancing valves {toc}
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### Each PICV shall be selected so the terminal minimum controllable flow falls within the device's controllable range.
−#### A PICV sized only to design flow can lose control authority near minimum flow if the controllable range is too narrow; the specifier must provide both the design flow and the minimum controllable flow (typically 10 to 15% of maximum Cv) as selection criteria. {note}
+#### A PICV sized only to design flow can lose control authority near minimum flow if the controllable range is too narrow; the specifier must provide both the design flow and the minimum controllable flow (typically 10 to 15% of maximum Cv) as selection criteria.
### Each PICV shall be furnished complete with its modulating actuator as a single product unless the Contract Documents explicitly assign actuator supply to the BAS contractor.
−#### On some projects the BAS contractor expects to furnish actuators separately; the specification must state explicitly whether the PICV is furnished complete with actuator or whether the actuator is furnished by others, to avoid a gap or a duplicate purchase. {note}
+#### On some projects the BAS contractor expects to furnish actuators separately; the specification must state explicitly whether the PICV is furnished complete with actuator or whether the actuator is furnished by others, to avoid a gap or a duplicate purchase.
### The PICV actuator control signal shall be compatible with the building automation system output specified in [[sync/building-automation-system]].
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### Terminal design flow {toc}
−#### The design flow and minimum controllable flow for each terminal shall be taken from the terminal schedule. {note}
+#### The design flow and minimum controllable flow for each terminal shall be taken from the terminal schedule.
#### Terminal flow assignments are coordinated from the equipment schedule on the drawings: [[drawing: terminal unit schedule]].
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## Strainer type {toc}
−### Y-pattern strainers shall be used for general protection at sizes up to 2 in. and where the pressure drop allowance is modest. {note}
+### Y-pattern strainers shall be used for general protection at sizes up to 2 in. and where the pressure drop allowance is modest.
### Basket (pot) strainers shall be used at sizes 3 in. and larger and where a large dirt-holding capacity or low pressure drop is required.
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## Screen and mesh {toc}
−### Strainer screens shall be stainless steel. {note}
+### Strainer screens shall be stainless steel.
### Strainer screen mesh shall match the protection requirement of the downstream equipment.
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## Body material {toc}
−### Strainer bodies shall be bronze on copper piping and at sizes 2-1/2 in. and smaller. {note}
+### Strainer bodies shall be bronze on copper piping and at sizes 2-1/2 in. and smaller.
### Strainer bodies shall be cast iron or ductile iron only on steel piping and only at sizes 3 in. and larger.
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## Blow-down and isolation {toc}
−### Strainers 3 in. and larger shall be furnished with a blow-down connection and valve. {note}
+### Strainers 3 in. and larger shall be furnished with a blow-down connection and valve.
### Each strainer 3 in. and larger shall be provided with upstream and downstream isolation so the screen can be serviced without draining the system.
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### Magnetic separation captures the ferrous particles (magnetite) that coalescing media alone passes; it is most valuable on systems with steel piping or cast iron components where iron oxide sludge forms. {note}
+### The in-line air/dirt separator type shall be specified, including a magnetic element where the system includes steel piping or cast-iron components.
+
```datasheet
label: In-Line Air/Dirt Separator Type
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```
+### The in-line air/dirt separator body material shall be specified for the served circuit.
+
```datasheet
label: In-Line Separator Body Material
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```
+### The in-line air/dirt separator connection size shall be specified to match the served circuit's design flow.
+
```datasheet
label: In-Line Separator Connection Size
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## Pressure gauges {toc}
−### Pressure gauges shall be selected so that the normal operating pressure falls within the middle third of the dial scale. {note}
+### Pressure gauges shall be selected so that the normal operating pressure falls within the middle third of the dial scale.
#### A gauge whose full scale equals the operating pressure runs at the top of its range, where resolution and accuracy are poor; selecting full scale at roughly twice the operating pressure puts the needle in the readable middle third. {note}
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## Thermometers and wells {toc}
−### Thermometers shall be provided at supply and return of each major piece of equipment and where indicated for system monitoring. {note}
+### Thermometers shall be provided at supply and return of each major piece of equipment and where indicated for system monitoring.
### Every thermometer and every temperature sensor inserted into the piping shall be installed in a thermowell.
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## Flexible connectors installed on pump suction shall be rated for full vacuum at the operating temperature.
−### A spherical rubber connector can collapse under the vacuum that can develop at a pump suction; suction-side connectors must be verified for both pressure and full vacuum at operating temperature, or a connector type not subject to collapse must be used. {note}
+### A spherical rubber connector can collapse under the vacuum that can develop at a pump suction; suction-side connectors must be verified for both pressure and full vacuum at operating temperature, or a connector type not subject to collapse must be used.
## Where the project is in a seismic design category requiring flexible joints, connector selection and anchorage shall comply with the project seismic requirements.
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### Drain, vent, and sample valve locations shall be coordinated with the piping layout: [[drawing: piping plan low and high points]]. {note}
+### The hose-end drain valve size shall be specified and coordinated with the piping plan low points.
+
```datasheet
label: Hose-End Drain Valve Size
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```
+### The air vent type at piping high points shall be specified and coordinated with the piping plan high points.
+
```datasheet
label: Air Vent Type at High Points
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```
+### Whether sample valves are provided at accessible monitoring points on open-loop circuits shall be specified.
+
```datasheet
label: Sample Valve Provision (open-loop circuits)
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## Balancing valves and flow control devices shall be installed with the manufacturer's required straight pipe length upstream and downstream of the device.
−### Flow control devices read and meter flow accurately only in developed flow; the upstream and downstream straight runs the manufacturer specifies must be honored or the balanced flow will be wrong. {note}
+### Flow control devices read and meter flow accurately only in developed flow; the upstream and downstream straight runs the manufacturer specifies must be honored or the balanced flow will be wrong.
## Pressure gauges and thermometers shall be installed where they can be read from the operating floor or an accessible platform.
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- One spare screen per strainer size/type
```