6.6004.1 Central/Common Exhaust Fan Serving Multiple Dwelling Units via Common Duct(s) and Dwelling Unit Branches

Topic: 
Exhaust
Subtopic: 
Exhaust Ventilation Systems
Desired Outcome: 
Multiport fan system installed to provide required ventilation
Note: 
The authority having jurisdiction may require that a licensed professional perform certain tasks outlined in this detail.
For supporting material, see Referenced Standards.
TitleSpecification(s)Objective(s)
6.6004.1a
Pre-inspection

Specifications will be field verified as appropriate to site conditions by installer

Ensure appropriate design for installation

6.6004.1b
Air flow

ASHRAE ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers, www.ashrae.org 62.2 and local code requirements should be followed for identifying design airflow rates within apartment dwelling units.

All other areas will follow local code requirements and/or ASHRAE ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers, www.ashrae.org 62.1 requirements

Air flows will be measured in accordance with ANSI ANSI American National Standards Institute, www.ansi.org / ACCA ACCA Air Conditioning Contractors of America, www.acca.org Standard 5 or ANSI ANSI American National Standards Institute, www.ansi.org / ASHRAE ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers, www.ashrae.org Standard 111 and adjusted to meet design requirements

Exhaust sufficient air from desired locations to the outdoors

6.6004.1c
Fan specification

Motors of 1 horsepower (HP) or larger will be rated as Premium Efficiency by the National Electrical Manufacturer's Association (NEMA)

Fan will be capable of maintaining a minimum operating static pressure of .25 inches of water column (WC) or the pressure that is required by the system design to ensure proper operation of all system components

Motors less than 1 HP, used for continuous whole-building ventilation, will be rated by the Home Ventilation Institute to provide at least the required ventilation rate at a minimum operating static pressure of .25 inches WC or the pressure that is required by the system design to ensure proper operation of all system components

Ensure proper flow rate sizing of exhaust fans

6.6004.1d
Fan outlet termination

Outlet will be terminated outside of the building shell and will have a louvered cover and bird screen

Minimum distance of exhaust outlet from any doors, windows, or outside air intakes shall be in conformance with the applicable building code

Outlet will be sealed to prevent water intrusion and exhaust air leakage into building cavities

Direct exhaust to the outdoors and prevent re-entry

Prevent entry of weather and pests into building shell

Ensure occupant health and safety

6.6004.1e
Wiring

Wiring will be installed by a licensed contractor

Wiring will be installed in accordance with original equipment manufacturer specifications, and local and national electrical and mechanical codes

Refer to NFPA NFPA National Fire Protection Association, www.nfpa.org 70: National Electrical Code

Prevent an electrical hazard

6.6004.1f
Access

Fan and service switch Service switch An electrical switch that controls the complete flow of electricity to a mechanical device will be accessible for maintenance

Ensure unit and service switch Service switch An electrical switch that controls the complete flow of electricity to a mechanical device are accessible for maintenance or replacement

6.6004.1g
Outdoor/indoor fan mounting

Fan will be oriented so the equivalent length of the duct run is as short as possible

Fan will be mounted securely in accordance with manufacturer specifications and local code requirements (in terms of seismic restraints, vibration, and noise control)

Fan will be isolated from the building framing unless specifically designed to be directly attached

Ensure short duct runs to achieve optimum air flows

Ensure mounting is installed securely

Ensure fan housing or building framing does not shake, rattle, or hum when operating

Minimize noise

6.6004.1h
Connecting exposed ductwork

All exposed ductwork outside of the building will be insulated to a minimum R-8, protected from weather exposure, and sealed at all penetrations into building shell

Ensure durability and energy efficiency of ductwork

6.6004.1i
Fan/duct riser connection

If fan is on curb, the riser will be flashed to the top of the curb and the fan will be sealed to the riser flashing

If the fan is separate from the curb, the riser will be flashed to the top of the curb

Duct connector will be sealed to the top of the riser flashing

Ductwork will be attached via a flexible connection and will maintain the intended fan opening

Provide the most efficient air transfer from targeted location to exhaust location

6.6004.1j
Backdraft dampers

A backdraft damper Backdraft damper A damper that allows air to flow in only one direction will be installed at or near the fan

A backdraft damper Backdraft damper A damper that allows air to flow in only one direction will be installed at each dwelling unit unless the fan runs on a continuous operating system

Prevent reverse air flow when the system is off

Prevent spread of contaminants between dwelling units

6.6004.1k
Combining intake ducts

All individual intake ducts will be combined on the inlet side of fan (e.g., Y-fitting, T-fitting, collector box)

Exhaust air from desired locations to the outdoors

6.6004.1l
Duct connections

All riser ducts or plenums will be connected and sealed to applicable intakes, collector box, fan, and termination fitting

Sealing activities will not interfere with the operation of fire dampers, balancing dampers, or backdraft dampers

Ducts will be connected and sealed in accordance with the applicable code adopted by the jurisdiction

Exhaust air from desired locations to the outdoors

Preserve integrity of the duct system and building envelope Envelope The separation between the interior and exterior environments of a building that includes a combination of air and thermal barrier

6.6004.1m
Insulation

All components outside of the thermal envelope Envelope The separation between the interior and exterior environments of a building that includes a combination of air and thermal barrier will be insulated to a minimum of R-8 or equivalent to local codes

Preserve integrity of the duct system

Prevent condensation in ductwork

Prevent heat loss

6.6004.1n
Register boot to interior surface seal

Register boot will be sealed to interior surfaces with sealants compatible to their intended surfaces

Sealants will be continuous and meet fire barrier specifications

Prevent air leakage around boot

Ensure a permanent seal to the building air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary

Prevent a fire hazard

6.6004.1o
Preventing air leakage caused by exhaust fans

Walls, ceilings, and floors will be sealed to separate any occupied space from any unconditioned spaces and adjacent dwelling units

Refer to ASHRAE ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers, www.ashrae.org 62.2 Addendum J

Ensure occupant health and safety

Prevent air leakage into the building and dwelling units from other spaces (e.g., adjacent dwelling units, garages, unconditioned crawl spaces, unconditioned attics)

6.6004.1p
Balance and flow

Air flows will be measured and adjusted to match the design specification in accordance with ANSI ANSI American National Standards Institute, www.ansi.org ACCA ACCA Air Conditioning Contractors of America, www.acca.org Standard 5 or ANSI ANSI American National Standards Institute, www.ansi.org / ASHRAE ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers, www.ashrae.org Standard 111

Achieve the desired air flows to and from the desired locations

6.6004.1q
Combustion zone testing

Pressure effects caused by fans will be assessed and corrected when found outside of combustion safety standards

Ensure safe operation of combustion appliances

6.6004.1r
Fire dampers

Fire dampers must be accessible for inspection and/or testing by the local authorities; if fire dampers are not accessible from a grill or register, an access door in the ductwork is required

Sealing activities will not interfere with the operation of fire dampers, balancing dampers, or backdraft dampers

Type B fire dampers will be used as required by fire code

Ensure access to fire dampers for safe operation

Minimize static pressure

Maximize air flow

6.6004.1s
Occupant/property manager education

Occupant/property manager will be educated on purpose and value of system

Property manager will be instructed on all maintenance procedures

Ensure occupant health and safety

Preserve integrity of system