1 Scope

NOTE This specification covers the selection, construction, rating, performance, accessories, installation, and testing of general-purpose HVAC fans furnished as discrete pieces of equipment — that is, fans that are scheduled, rated, and installed in their own right rather than as an integral section of a larger packaged unit. (1.1)

NOTE Equipment covered includes centrifugal fans, axial fans, propeller fans, inline cabinet and tubular fans, utility and single-width single-inlet (SWSI) exhaust fans, roof- and wall-mounted power ventilators, ceiling exhaust fans, and dedicated grease-laden kitchen exhaust fans. (1.2)

NOTE The work includes the fan and its housing, the impeller, the motor and drive, the bearings, the integral accessories (dampers, screens, curbs, isolation, weatherproofing), and the electrical and controls connection point. (1.3)

1.4 All equipment shall comply with the applicable AMCA rating and certification standards, ASHRAE 90.1 for fan energy performance, NFPA 90A for fire and smoke safety, and the applicable UL listing.

NOTE A fan selected near its peak static efficiency runs quietly, draws the least energy, and tolerates the inevitable field variation in system resistance, while the same air quantity delivered by a fan selected far up a steep portion of its curve, or in its stall region, will be noisy, energy-hungry, and unstable. (1.5)

NOTE This standard treats the certified rating basis, the operating point relative to the curve, and the Fan Energy Index as primary requirements rather than afterthoughts, because the value of a fan to the building is set at selection, not installation; a correctly selected fan rigidly bolted to structure and hard-ducted will still transmit noise and vibration that no amount of selection care can recover. (1.6)

1.7 Scope Boundary

NOTE The boundary of work under this standard is the fan as a scheduled assembly, from its inlet connection to its outlet connection, together with the integral accessories and the line-side electrical termination. (1.7.1)

1.7.2 Fans that are a rated section of packaged equipment are covered by that equipment's standard and are excluded here.

1.7.3 The ductwork upstream and downstream of the fan is covered by HVAC DuctworkHVAC DuctworkResolves to the current edition.sync/hvac-ductwork.

1.7.4 The variable-frequency drives that modulate fan speed are covered by HVAC Variable Frequency DrivesHVAC Variable Frequency DrivesResolves to the current edition.sync/hvac-variable-frequency-drives.

1.7.5 The diffusers, grilles, and terminal devices are covered by HVAC Air Distribution DevicesHVAC Air Distribution DevicesResolves to the current edition.sync/hvac-air-distribution-devices.

1.7.6 The field measurement and balancing of installed airflow is covered by Testing Adjusting And BalancingTesting, Adjusting, and Balancing for HVACResolves to the current edition.sync/testing-adjusting-and-balancing.

2 Referenced Standards

2.1 Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.

2.2 Where conflicts exist between referenced standards, the adopted energy and mechanical codes, the equipment manufacturer's instructions, or the contract documents, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.

2.3 Standards Table

Standard	Title
ANSI/AMCA 99	Standards Handbook (fan classification, arrangement, and spark-resistant construction definitions)
ANSI/ASHRAE 51 / ANSI/AMCA 210	Laboratory Methods of Testing Fans for Certified Aerodynamic Performance Rating
ANSI/AMCA 211	Certified Ratings Program — Product Rating Manual for Fan Air Performance
ANSI/AMCA 300	Reverberant Room Method for Sound Testing of Fans
ANSI/AMCA 311	Certified Ratings Program — Product Rating Manual for Fan Sound Performance
ANSI/AMCA 204	Balance Quality and Vibration Levels for Fans
ANSI/AMCA 208	Calculation of the Fan Energy Index (FEI)
ANSI/ASHRAE/IES 90.1	Energy Standard for Buildings Except Low-Rise Residential Buildings
UL 705	Power Ventilators (including Supplement SC for restaurant/grease exhaust)
UL 762	Power Roof Ventilators for Restaurant Exhaust Appliances (where still referenced)
NFPA 90A	Standard for the Installation of Air-Conditioning and Ventilating Systems
NFPA 96	Ventilation Control and Fire Protection of Commercial Cooking Operations
NEMA MG-1	Motors and Generators
SMACNA HVAC Duct Construction Standards	SMACNA HVAC Duct Construction Standards — Metal and Flexible
ASHRAE Handbook	HVAC Systems and Equipment (Fans chapter); Applications (Sound and Vibration Control)

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following for the Engineer's review and acceptance before fans are ordered.

Manufacturer's product data for each fan type, identifying the fan class, AMCA drive arrangement, rotation and discharge, motor position, materials, and finish
Certified fan performance curves (not catalog point selections) for each scheduled fan, plotting static pressure, brake horsepower, and efficiency against airflow, with the design operating point clearly marked and the certified-ratings basis (AMCA 210 / ASHRAE 51) identified
Fan sound power data by octave band for inlet, outlet, and casing-radiated paths, certified per AMCA 300 and rated under AMCA 311
The Fan Energy Index (FEI) at the design operating point, calculated per AMCA 208, with confirmation that it meets the value required by ASHRAE 90.1 and the adopted energy code, or documentation that the fan is within a listed exemption
Motor data sheet showing horsepower, voltage and phase, full-load amperes, service factor, efficiency class (NEMA Premium or applicable), enclosure, insulation class, and bearing type; for EC motors, the integral controller, turndown range, and signal interface
Drive data: for belt drive, the sheave sizes, belt type and quantity, service factor on the drive, and the adjustable range; for direct drive, the coupling or shaft arrangement
Bearing data with the calculated rating life (L10) at the design speed and load
Vibration isolation selection for each fan, with isolator type, static deflection, and the load distribution
Accessory schedule (dampers, bird/insect screens, curbs, disconnects, drains, coatings, dampers, guards) keyed to each fan
For grease-exhaust fans, the UL 705 (Supplement SC) or UL 762 listing and the hinged-base/drain provisions per NFPA 96
For spark-resistant fans, the AMCA 99 spark-resistant construction type (A, B, or C) and the bill of materials documenting the non-ferrous components
Wiring diagram showing the line-side termination, integral disconnect or controller, and the control/interlock interface to the building automation system or the variable-frequency drive
Structural data: operating and shipping weights, mounting and anchorage points, and roof-curb and seismic-anchorage details where applicable

Action Submittals Requiredcheckbox

☐ Product data with class, arrangement, rotation/discharge, materials

☑ Certified fan performance curves with operating point marked

☐ Octave-band sound power data (AMCA 300 / 311)

☐ Fan Energy Index (FEI) calculation per AMCA 208

☐ Motor data sheet (efficiency, enclosure, insulation, bearings)

☐ Drive data (belt sheaves/service factor or direct-drive arrangement)

☐ Bearing rating life (L10) calculation

☐ Vibration isolation selection (type and static deflection)

☐ Accessory schedule keyed to each fan

☐ Grease-exhaust UL listing and NFPA 96 provisions

☐ Spark-resistant construction type and non-ferrous bill of materials

☐ Wiring diagram and BAS/VFD control interface

☐ Weights, anchorage, and roof-curb/seismic details

3.1.2 Procurement and fabrication shall not proceed until action submittals have been reviewed and returned.

3.1.3 Submittals shall be coordinated with the variable-frequency drive, electrical, and structural scopes before any item is submitted.

3.2 Closeout Submittals

3.2.1 At substantial completion the Contractor shall provide operation and maintenance data for each fan, including the following:

As-installed performance point
Lubrication type and interval for re-greaseable bearings
Belt type and tension procedure
Sheave change procedure for any field airflow adjustment
Recommended spare-parts list

Required Closeout Submittalscheckbox

☑ As-installed performance point

☑ Lubrication type and interval for re-greaseable bearings

☑ Belt type and tension procedure

☑ Sheave change procedure for field airflow adjustment

☑ Recommended spare-parts list

3.2.2 Where the fan was field-adjusted to meet the balanced airflow, the final sheave or speed setting shall be recorded.

4 Quality Assurance

4.1 Certified Ratings

4.1.1 All scheduled fans shall be rated and bear the AMCA Certified Ratings Program (CRP) seal for both air performance and sound, except where a fan type is not eligible for AMCA certification.

AMCA Certified Ratings Requiredradio

● Air (AMCA 210/211) and sound (AMCA 300/311) certified — bear CRP seal (standard)

○ Air performance (AMCA 210/211) certified; sound certified where fan type is eligible

○ Not AMCA-certified — only where fan type is not eligible for the program (justify)

4.1.2 Air performance shall be tested in accordance with AMCA 210 (ANSI/ASHRAE 51) and certified under AMCA 211.

4.1.3 Sound performance shall be tested in accordance with AMCA 300 and certified under AMCA 311.

4.1.4 Ratings interpolated, extrapolated, or otherwise outside the certified range shall not be accepted.

NOTE The CRP seal is the assurance that the published curve and the published sound levels were obtained by a standardized laboratory method and verified by AMCA rather than being interpolated or optimistic catalog values; a fan selected from an uncertified rating may not deliver the scheduled air at the scheduled power or sound. (4.1.5)

4.2 Operating Point Relative to the Curve

4.2.1 Each fan shall be selected so that the design operating point falls in the stable, efficient portion of its certified curve — at or near peak static efficiency and clear of the stall (surge) region on the left of the curve and of the steep, runaway region on the far right.

4.2.2 The selection submittal shall demonstrate the operating point on the certified curve.

4.2.3 Where a fan will be speed-modulated by a variable-frequency drive, the operating point shall remain stable across the intended turndown range.

NOTE Selecting on the unstable left of the peak causes pulsation, noise, and unpredictable airflow, while selecting far to the right wastes energy and runs the motor near or beyond its limit. (4.2.4)

4.3 Code Compliance

4.3.1 Fans and their installation shall comply with NFPA 90A for fire and smoke safety in air-distribution systems, with the adopted mechanical and energy codes, and with the applicable UL listing for the fan's service.

4.3.2 Fans handling air from commercial cooking operations shall additionally comply with NFPA 96.

4.3.3 The Contractor shall maintain a copy of the applicable listings and the manufacturer's installation instructions at the site.

4.4 Source Quality — Run Test

4.4.1 Fans in vibration category BV-3 and higher per AMCA 204 (typically larger and higher-power fans) shall receive a factory final-assembly run test before shipment, with the as-built rotor balanced to the balance-quality grade required for the category and the operating vibration verified to be within the AMCA 204 limit for the application.

4.4.2 The run-test record shall be furnished.

4.4.3 Smaller fans (BV-1/BV-2 applications) shall be balanced to the applicable grade but need not be individually run-tested unless specified.

5 Environmental and Service Conditions

5.1 Airstream and Service

5.1.1 The fan construction, materials, and bearing arrangement shall suit the airstream it handles.

Airstream Serviceselect

Clean, dry, ambient supply or general exhaust (standard)

Moist or wet exhaust (toilet, shower, pool — corrosion-resistant construction)

Corrosive/chemical exhaust (coated or non-metallic construction)

Grease-laden kitchen exhaust (UL-listed grease fan, NFPA 96)

High-temperature exhaust (heat-fan construction, high-temp bearings/motor)

Hazardous/flammable exhaust (spark-resistant construction per AMCA 99)

NOTE Clean, dry, ambient-temperature supply and general exhaust air is the default service and permits standard steel construction with a standard motor. (5.1.2)

5.1.3 Airstreams that are corrosive, high-temperature, grease-laden, moisture-laden, or that may contain flammable or combustible material change the material, finish, bearing, motor enclosure, and spark-resistance requirements and shall be identified for each fan.

5.2 Ambient and Altitude

NOTE Fan air performance is certified at standard air density (0.075 lb/ft³, sea level, 70°F). (5.2.1)

5.2.2 Where the fan operates at elevated altitude or handles air at a temperature far from standard, the brake horsepower and the as-installed pressure shall be corrected for the actual air density.

Air Density Correction Basisradio

● Standard air (0.075 lb/ft³) — sea level, ambient temperature (standard)

○ Site-corrected for altitude and/or airstream temperature (per drawings/schedule)

5.2.3 The motor shall be sized for the highest-density (coldest, lowest-altitude) condition the fan will start and run against, because density-corrected brake horsepower rises as air gets denser.

5.2.4 Outdoor and rooftop fans shall be rated for the site ambient temperature extremes and weatherproofed for the exposure.

6 Fan Types and Selection

6.1 Fan Type by Application

6.1.1 The fan type shall suit the pressure, airflow, available space, sound limit, and airstream of each application.

Fan Typeselect

Centrifugal, housed (scroll) — ducted supply/return, higher pressure

Centrifugal, plenum/plug (unhoused) — supply into a plenum, AHU-style

Inline cabinet / tubular centrifugal — ceiling-space duct runs

Vaneaxial — high volume, moderate pressure, in-duct

Tubeaxial — high volume, low-moderate pressure, in-duct

Propeller (panel/wall) — high volume, very low pressure

Utility / SWSI — general exhaust, single-width single-inlet

Roof-mounted power ventilator (downblast or upblast)

Wall-mounted power ventilator

Ceiling-mounted exhaust fan (toilet/general)

Kitchen grease exhaust (UL-listed upblast roof)

NOTE Centrifugal fans develop higher pressure efficiently and are the default for ducted supply and return systems and for higher-resistance exhaust; axial fans move large volumes at low to moderate pressure in a compact, in-duct envelope; propeller fans move large volumes against very low pressure and are used for panel and wall ventilation; inline cabinet and tubular fans package a centrifugal or mixed-flow impeller in a straight-through housing for ceiling-space duct runs; and roof and wall power ventilators and ceiling exhaust fans are pre-engineered exhaust packages. (6.1.2)

6.2 Centrifugal Impeller (Wheel) Type

NOTE For centrifugal fans the impeller blade form sets the pressure capability, the efficiency, the sound, and the tolerance of dirty air. (6.2.1)

NOTE Airfoil (AF) blades are the most efficient and quietest and are the default for clean air, but the hollow blade can fill with dirt or condensate; backward-inclined and backward-curved (BI/BC) blades give nearly the efficiency of airfoil with greater tolerance of moist or lightly contaminated air; forward-curved (FC) blades are compact and quiet at low pressure and are typical of small packaged and cabinet fans but are inefficient and unstable at high pressure; and radial and radial-tip blades resist material buildup and are used for dirty or material-handling exhaust at the cost of efficiency. (6.2.2)

6.2.3 The centrifugal impeller (wheel) type shall be specified for each fan, selected to suit the air cleanliness, efficiency, and pressure demands of its service.

Centrifugal Impeller Typeselect

Airfoil (AF) — highest efficiency, lowest sound, clean air (standard for large centrifugal)

Backward-inclined / backward-curved (BI/BC) — efficient, tolerant of moist air

Forward-curved (FC) — compact, low-pressure, small cabinet/packaged fans

Radial / radial-tip — material-handling and dirty exhaust

6.3 Scheduled Airflow and Static Pressure

6.3.1 The design airflow and external static pressure for each fan shall be as scheduled on the mechanical drawings.

Design Airflowrange

cfm

5020050010002000500010000200004000060000

Per drawings

Design External Static Pressurerange

in. w.g.

0.18

Default: 1.5 in. w.g.

Per drawings

6.3.2 The fan shall be selected to deliver the scheduled airflow at the scheduled total (or external) static pressure at the certified operating point.

6.3.3 The static pressure used for selection shall account for the full system resistance including filters at their final (loaded) resistance, coils, dampers, louvers, ductwork, and the inlet/outlet system effect, so that the fan is not starved by resistance the catalog point ignored.

7 Fan Energy Index and Efficiency

7.1 Fan Energy Index (FEI) Compliance

7.1.1 Each fan and each fan array shall meet the minimum Fan Energy Index required by the adopted edition of ASHRAE 90.1 at the design operating point, with FEI calculated in accordance with AMCA 208.

Minimum Fan Energy Index (FEI) at Design Pointrange

FEI

11.051.11.211.311.4

FEI Compliance Pathradio

● Meets ASHRAE 90.1 minimum FEI at design point per AMCA 208 (standard)

○ Within ASHRAE 90.1 small-fan / special-application exemption (document)

7.1.2 The selection submittal shall report the FEI at the scheduled operating point.

7.1.3 Fans within the code's small-fan and special-application exemptions shall be documented as such.

NOTE The Fan Energy Index is the ratio of the electrical input power of a reference fan to the electrical input power of the actual fan at the same duty point; a higher FEI is more efficient, ASHRAE 90.1-2019 and later editions require a minimum FEI of 1.00 for covered fans, and because FEI accounts for the motor and drive it captures the real wire-to-air efficiency and replaced the older Fan Efficiency Grade (FEG) metric. (7.1.4)

7.2 Selection Margin and Stability

7.2.1 Fans shall not be oversized with arbitrary safety factors added to both airflow and pressure.

7.2.2 Where a margin is warranted, it shall be a deliberate, documented allowance (for example, a modest pressure margin for filter loading) and the FEI shall still be met at the actual design point.

7.2.3 The fan and its drive shall be capable of meeting the scheduled airflow at the increased resistance of fully loaded filters without the motor being overloaded.

NOTE An oversized fan operates back on its curve at low efficiency and high sound, and on a variable-volume system it spends its life throttled. (7.2.4)

8 Construction, Class, and Arrangement

8.1 AMCA Construction Class

8.1.1 Centrifugal and axial fans shall be furnished in the AMCA construction class (Class I, II, III, or as defined in AMCA 99) appropriate to the maximum operating speed and pressure of the selection.

AMCA Construction Classselect

Class I — standard pressure/speed range (most HVAC supply and exhaust)

Class II — higher pressure/speed range

Class III — high pressure/speed range

As required by selection within certified class envelope (manufacturer to confirm)

8.1.2 The selected fan's operating point shall fall within the certified pressure-speed envelope of its class.

NOTE The construction class sets the structural design limits — the maximum static pressure and the maximum tip speed (RPM) the housing and impeller are built to withstand — and a higher class denotes heavier construction rated for higher pressure and speed; a fan operated beyond its class limit is a structural hazard. (8.1.3)

8.2 Drive Arrangement, Rotation, and Discharge

8.2.1 The AMCA drive arrangement, the direction of rotation, and the discharge position for each centrifugal fan shall be coordinated with the installed orientation so the fan fits the space and connects to the duct without field modification.

Centrifugal Drive Arrangementselect

Arrangement 4 — direct drive, impeller on motor shaft, no fan bearings

Arrangement 1 — belt drive, impeller overhung, two bearings on pedestal

Arrangement 3 — belt drive, impeller between bearings

Arrangement 9/10 — belt drive, impeller overhung, motor on/within base

As required by installed orientation (coordinate with layout)

Rotation and Dischargetext

Enter value...

Per drawings (deferred by default)

8.2.2 Rotation (clockwise or counter-clockwise viewed from the drive side) and discharge (top, bottom, or angular) shall match the layout shown.

NOTE Arrangement defines how the impeller is supported and where the motor sits — for example, Arrangement 1 and 9/10 for belt drive with the impeller overhung on its own bearings, Arrangement 3 with the impeller between bearings, and Arrangement 4 for direct drive with the impeller overhung on the motor shaft and no fan bearings. (8.2.3)

8.3 Housing and Impeller Construction

8.3.1 The fan housing and impeller shall be of the gauge and reinforcement appropriate to the construction class and pressure, with continuously welded or otherwise sealed seams on pressure boundaries.

8.3.2 The impeller shall be statically and dynamically balanced to the AMCA 204 grade for its category and keyed or otherwise positively secured to the shaft.

8.3.3 Housings of centrifugal fans shall have a streamlined inlet (inlet cone) matched to the impeller.

8.3.4 Axial fan housings shall be of the tubular or vaneaxial form scheduled, with guide vanes where the rating depends on them.

8.4 Materials and Finish

8.4.1 Standard fans shall be fabricated of carbon steel with a corrosion-resistant factory finish (baked enamel or equivalent) suitable for indoor service.

Material and Finishselect

Carbon steel, baked-enamel finish — indoor standard

Galvanized steel — moist/general exhaust and rooftop

Aluminum — lightweight rooftop/wall and corrosion service

Chemical-resistant coated steel — mildly corrosive exhaust

Fiberglass-reinforced plastic (FRP) — corrosive chemical exhaust

8.4.2 Fans in moist, washdown, coastal, or mildly corrosive service shall be galvanized, aluminum, or coated with a chemical-resistant coating.

8.4.3 Fans in aggressive chemical exhaust shall be fiberglass-reinforced plastic (FRP) or a coated metal selected for the contaminant.

8.4.4 Exterior and rooftop fans shall have a weather-resistant finish suitable for the exposure.

8.4.5 The material and finish shall be scheduled for each fan and shall be consistent with the airstream service selected above.

8.5 Spark-Resistant Construction (Hazardous Exhaust)

8.5.1 Where the airstream may contain flammable gas, vapor, or combustible dust, the fan shall be furnished with spark-resistant construction per AMCA 99, of the type matched to the hazard.

Spark-Resistant Construction Type (AMCA 99)radio

● None — non-hazardous airstream (standard)

○ Type C — no two ferrous parts can rub/strike on wheel shift

○ Type B — non-ferrous impeller and rub ring/inlet strip in ferrous housing

○ Type A — all airstream parts non-ferrous (highest spark resistance)

8.5.2 Spark-resistant construction addresses sparks from within the fan only; it is not a substitute for an electrical hazardous-location (explosion-proof) motor rating, which shall be specified separately where the area classification requires it.

NOTE Type A is full non-ferrous construction (impeller, housing, and all airstream parts non-ferrous) and offers the highest spark resistance; Type B uses a non-ferrous impeller and a non-ferrous rub ring or inlet strip in the ferrous housing so that a wheel-to-housing rub cannot strike a ferrous spark; and Type C is constructed so that a shift of the wheel cannot bring two ferrous parts into rubbing or striking contact. (8.5.3)

8.6 Grease-Laden Exhaust Construction

8.6.1 Fans serving commercial kitchen hoods and grease ducts shall be UL-listed for grease exhaust (UL 705 Supplement SC, or UL 762 where still referenced) and installed per NFPA 96.

8.6.2 Such fans shall be of the upblast roof or in-line configuration with a hinged base or hinged service curb to allow cleaning of the fan and the duct, a grease drain and collection cup, and a continuous weld or sealed construction on grease-wetted surfaces so grease cannot leak onto the roof.

8.6.3 The motor shall be kept out of the grease-laden airstream.

9 Motors and Drives

9.1 Motor — General

9.1.1 Fan motors shall comply with NEMA MG-1 and shall be of the efficiency class required by the adopted energy code (NEMA Premium for the polyphase ratings to which the regulation applies).

Motor Enclosureselect

ODP (open drip-proof) — clean, dry indoor

TEFC (totally enclosed fan-cooled) — outdoor, moist, or dirty (standard for exterior)

TEAO (totally enclosed air-over) — air-over service in the airstream

Explosion-proof / hazardous-location — classified areas

Motor Efficiency Classradio

● NEMA Premium efficiency (standard where regulated)

○ EC motor integral efficiency (where EC motor selected)

9.1.2 The enclosure shall suit the location and airstream — open drip-proof (ODP) for clean indoor air, totally enclosed fan-cooled (TEFC) for outdoor, dirty, or moist locations, and a hazardous-location rating where the area classification requires it.

9.1.3 The motor shall be sized so that the brake horsepower at the design operating point, density-corrected for the worst-case condition, does not exceed the motor's rated horsepower.

9.1.4 On fans where the brake horsepower rises across the operating range, the motor shall be non-overloading across that range.

9.2 Direct Drive vs Belt Drive

NOTE Direct-drive fans (impeller mounted on the motor shaft, AMCA Arrangement 4, or a close-coupled coupling) eliminate the belt, sheaves, and belt maintenance, run quieter, and are the default for small and medium fans and for any fan whose airflow is set by a variable-frequency drive or an EC motor rather than by a sheave. (9.2.1)

9.2.2 The drive type shall be specified for each fan, stating whether it is direct drive or belt drive.

Drive Typeradio

● Direct drive (Arrangement 4 or close-coupled) — small/medium and VFD/EC fans (standard)

○ Belt drive — larger fans and sheave-set operating points

9.2.3 Belt drive remains appropriate for larger fans and where the exact speed must be set by sheave selection to hit a non-standard operating point.

9.2.4 Belt drives shall have an adjustable (variable-pitch) drive for initial balancing and a fixed drive for the final setting where required, with the drive selected on a service factor of not less than 1.5 on the motor horsepower (or per the manufacturer's standard for the service), and a belt guard provided.

9.3 Speed Control and EC Motors

9.3.1 Where a fan's airflow is to be modulated, the speed shall be controlled by an electronically commutated (EC) motor with an integral controller for smaller fans, or by an external variable-frequency drive for larger fans, rather than by mechanical throttling.

Speed Control Methodradio

● Constant speed — no modulation (standard for simple exhaust)

○ EC motor with integral controller and 0-10V/BAS signal (small modulated fans)

○ External variable-frequency drive, inverter-duty motor (larger modulated fans)

9.3.2 EC motors are the default for small exhaust and inline fans needing setpoint adjustment or modulation, accepting a 0–10 V or BAS speed signal and needing no separate drive.

9.3.3 Larger modulated fans shall be served by an external variable-frequency drive per HVAC Variable Frequency DrivesHVAC Variable Frequency DrivesResolves to the current edition.sync/hvac-variable-frequency-drives, and the motor shall be inverter-duty rated (insulation and bearing protection suitable for VFD operation) where so served.

NOTE Throttling a constant-speed fan wastes the energy the fan curve and the affinity laws would otherwise save. (9.3.4)

10 Bearings

10.1 Bearing Type and Rating Life

10.1.1 Belt-drive and Arrangement 1/3/9/10 fans shall be furnished with anti-friction (ball or roller) bearings selected for a calculated basic rating life (L10) of not less than 40,000 hours at the design speed and load for general HVAC service, and not less than 80,000 hours for fans in continuous critical service, in accordance with the manufacturer's bearing rating.

Bearing Rating Life (L10) — Belt/Pedestal Fansrange

hours

4000080000100000200000

Bearing Lubricationradio

● Re-greaseable anti-friction bearings, extended grease lines where not accessible (standard)

○ Permanently lubricated / sealed-for-life bearings (small fans)

10.1.2 Bearings shall be of the self-aligning, pillow-block or cartridge type appropriate to the arrangement and shall be re-greaseable, with grease lines extended to an accessible point on fans where the bearing is not reachable in place.

10.1.3 Direct-drive (Arrangement 4) fans use the motor's own bearings, which shall meet the motor's rating-life requirement.

11 Accessories

11.1 Integral Accessories

11.1.1 Fans shall be furnished with the integral accessories required for their service and location.

Fan Accessoriescheckbox

☐ Inlet/outlet duct flanges or collars

☑ Flexible duct connection at fan

☐ Factory-mounted disconnect switch

☐ Backdraft (gravity) damper

☐ Motorized control damper / interlock damper

☐ Bird/insect screen on open inlet or outlet

☐ Inlet/outlet safety guard

☐ Housing drain connection

☐ Belt guard (belt-drive fans)

☐ Weatherhood / weather cover (exterior)

NOTE Common accessories include inlet and outlet flanges or duct collars, a flexible connection at the duct, an integral or factory-mounted disconnect switch, a motorized or gravity backdraft damper, an inlet/outlet guard or bird/insect screen on open inlets, drain connections on housings subject to condensate or washdown, and weatherhoods on exterior intakes. (11.1.2)

11.1.3 The accessory schedule shall identify the accessories furnished with each fan so that field-furnished items (for example, a damper furnished under the ductwork scope) are not duplicated or omitted.

11.2 Roof Curbs and Mounting

11.2.1 Roof- and wall-mounted power ventilators shall be furnished with a prefabricated roof curb or wall-mount frame matched to the fan base and to the roof slope or wall, insulated and built to receive the fan with a continuous gasket so the connection is weathertight.

Roof/Wall Mountingselect

Prefabricated insulated roof curb, gasketed (standard for roof fans)

Hinged service curb (grease and serviceable roof fans)

Wall-mount frame with weather hood (wall ventilators)

Direct duct/structure mount (inline fans)

11.2.2 Curbs shall be of the height required to clear the roofing and flashing per the roofing standard, and grease-fan curbs shall be the hinged or vented type required by NFPA 96.

11.2.3 Curb and anchorage details shall be coordinated with the roof framing and roofing details.

12 Vibration Isolation

12.1 Isolation Selection

12.1.1 Every fan that connects to occupied building structure or to ductwork serving occupied spaces shall be isolated so its running vibration and the structure-borne noise it generates are not transmitted into the building.

Vibration Isolator Typeselect

Neoprene/rubber-in-shear mounts — small fans on grade or stiff slab

Spring isolators — most floor-mounted fans (deflection per fan speed/floor)

Restrained spring isolators — exterior, rooftop, or seismic regions

Spring hangers — suspended inline and cabinet fans

Internal/factory spring isolation base — packaged exhaust fans

Minimum Isolator Static Deflectionrange

in.

0.250.7511.52.53.5

12.1.2 The isolator type and its rated static deflection shall be selected per the ASHRAE Applications Handbook (Sound and Vibration Control) for the fan speed, the supported weight, and the floor span.

NOTE Slower fans and fans on long-span or upper floors need greater deflection to stay below the structure's natural frequency, because a hard or under-deflected isolator passes the very low-frequency rumble it was meant to block. (12.1.3)

12.2 Flexible Connections and Seismic Restraint

12.2.1 A flexible duct connection shall be installed at the fan inlet and outlet to break the metal-to-metal path between the running fan and the rigid duct.

12.2.2 The flexible connection shall have enough slack to flex but not so much that it bellows under pressure, and shall be of a fire-rated fabric where required by NFPA 90A.

12.2.3 In seismic-design regions, fans and their isolators shall be seismically restrained and anchored per the structural requirements, using restrained (snubber) isolators so the fan cannot walk or topple while still being isolated in normal operation.

13 Electrical and Controls Interface

13.1 Power Connection

13.1.1 Each fan shall be provided with a factory- or field-mounted disconnecting means within sight of the motor as required by NFPA 70, and shall be connected to the branch circuit indicated.

13.1.2 The fan nameplate full-load amperes and the supplied disconnect/overcurrent device shall be coordinated with the electrical scope.

13.1.3 EC-motor and VFD-driven fans shall have the controller or drive located and wired per the manufacturer's instructions and the drive standard.

13.2 Controls and Interlocks

13.2.1 The fan control interface shall be coordinated with the building automation system and with any required interlocks — for example, an exhaust fan interlocked to its makeup-air source or to a damper end switch, a kitchen exhaust fan interlocked with the hood fire-suppression and makeup-air systems per NFPA 96, or a fan started and modulated by the BAS.

Control Interfaceselect

Line-voltage on/off (local switch or BAS relay) — simple exhaust (standard)

BAS start/stop with proof-of-operation feedback

0-10V / 4-20mA speed signal to EC motor or VFD with feedback

Interlocked with makeup air / damper / hood suppression (kitchen, NFPA 96)

13.2.2 Where a fan is modulated, the speed-control signal (0–10 V, 4–20 mA, or BAS network) and the proof-of-operation feedback (current switch or differential pressure) shall be identified.

13.2.3 Smoke and fire damper and smoke-control interactions shall comply with NFPA 90A.

14 Testing

14.1 Factory Testing

14.1.1 Air performance and sound ratings shall be established by the certified-ratings testing described under Quality Assurance (AMCA 210/211 and AMCA 300/311); these are the basis of selection and no project-specific air or sound test is required for catalog-rated fans.

14.1.2 Where a fan is in vibration category BV-3 or higher per AMCA 204, the factory run test and balance verification required under Source Quality shall be performed and reported.

14.2 Field Testing and Balancing

14.2.1 After installation, the rotation, the motor amperage, the bearing temperature, and the running vibration of each fan shall be checked before it is placed in continuous service.

Field Start-Up Checkscheckbox

☑ Confirm correct rotation direction

☐ Measure and record motor amperage (within nameplate FLA)

☐ Check bearing temperature and running vibration

☐ Set and record belt tension (belt-drive fans)

☐ Adjust drive/speed to reach design airflow and record final setting

14.2.2 The fan rotation shall be confirmed correct.

14.2.3 Belt tension shall be set per the manufacturer, and any sheave adjustment needed to reach the design airflow shall be made and recorded.

14.2.4 This standard requires only that the fan be delivered in a condition (correct rotation, drive set, adjustable drive or speed signal available) that lets balancing reach the scheduled point; the measurement and balancing of installed airflow against the scheduled values is performed under Testing Adjusting And BalancingTesting, Adjusting, and Balancing for HVACResolves to the current edition.sync/testing-adjusting-and-balancing.

NOTE A backward-running centrifugal fan moves some air and develops some pressure, which masks the error until the airflow falls short on test. (14.2.5)

15 Installation

15.1 Fans shall be installed level, plumb, and aligned in accordance with this standard, the contract drawings, the manufacturer's instructions, and NFPA 90A.

15.2 Adequate clearance shall be maintained for belt and sheave service, bearing lubrication, motor removal, and impeller access.

15.3 The fan shall be supported entirely on its isolators or curb so that no load is carried by the connected ductwork, and the flexible connections shall be installed so they do not transmit force into the fan.

15.4 Inlet and Outlet System Effect

15.4.1 Fans shall be installed with the straight inlet and outlet duct conditions assumed in the rating, or the system effect of non-ideal connections shall have been added to the selection static pressure.

15.4.2 Inlet and outlet duct connections shall provide the straight length and the gradual transitions the manufacturer requires, coordinated against HVAC DuctworkHVAC DuctworkResolves to the current edition.sync/hvac-ductwork.

NOTE An elbow, a sharply transformed transition, or an obstruction close to the fan inlet or outlet spoils the airflow pattern the fan was rated with and adds a pressure penalty (system effect) that the fan cannot recover, so the result is a fan that "tests low" despite being the right size. (15.4.3)

15.5 Coordination

15.5.1 Fan locations, service clearances, roof-curb and anchorage points, electrical connections, and control interlocks shall be coordinated with the structural, roofing, electrical, ductwork, and controls scopes before rough-in.

15.5.2 Rooftop and exterior fan locations and curb details shall be coordinated with the roof plan and structural framing, and the fan electrical loads with the electrical drawings.

15.5.3 Where fans are part of a system served by the dedicated outdoor air or air distribution standards, the fan selection shall be consistent with Dedicated Outdoor Air SystemsDedicated Outdoor Air SystemsResolves to the current edition.sync/dedicated-outdoor-air-systems and HVAC Air Distribution DevicesHVAC Air Distribution DevicesResolves to the current edition.sync/hvac-air-distribution-devices.

16 Delivery, Storage, and Handling

16.1 Fans shall be delivered with shipping restraints on the impeller and isolators in place, with inlets and outlets covered to keep out debris and weather, and with the nameplate and rotation/arrow markings legible.

16.2 Fans shall be stored indoors or under cover, off the ground, and protected from weather, dust, and physical damage until installed.

16.3 Shipping restraints shall be removed only after the fan is set and before start-up, and their removal shall be verified.

16.4 The impeller shall not be used as a lifting or rigging point; fans shall be rigged from the lifting points the manufacturer provides.

17 Warranty

17.1 The Contractor shall warrant each fan and its installation against defects in materials and workmanship for a period of not less than one year from substantial completion, or for the longer period stated in the contract documents.

17.2 Motors, bearings, and drives shall carry at least the manufacturer's standard warranty for the component.

17.3 Any fan that fails to deliver its scheduled airflow at its scheduled static pressure because of an error in selection, rotation, drive setting, or installation (as distinct from a change in the system resistance outside the fan scope) shall be corrected at the Contractor's expense, including any sheave or speed change required to reach the scheduled point.

18 Spare Parts

18.1 The Contractor shall furnish the manufacturer's recommended spare parts for the fans.

Spare Parts to Furnishcheckbox

☑ One set of replacement belts per belt-drive fan (or per identical-fan group)

☐ Spare set of bird/insect screens or filters where applicable

☐ First-interval bearing lubricant for re-greaseable fans

☐ Spare backdraft damper actuator/spring where motorized

18.2 For belt-drive fans the spare parts shall include at minimum one complete set of replacement belts for each belt-drive fan (or each group of identical fans where the schedule so allows).

18.3 The Contractor shall furnish the lubrication products and quantities recommended for the first service interval of re-greaseable bearings.

18.4 Spare-part identification (fan tag, belt size and quantity, bearing part numbers) shall be listed in the closeout documents.