| 6.6003.4a
Wiring | Wiring will be installed in accordance with original equipment manufacturer specifications, and local and national electrical and mechanical codes | Prevent an electrical hazard |
| 6.6003.4b
Access | Fan and access switch shall be accessible for maintenance according to
NFPA
NFPA
National Fire Protection Association, www.nfpa.org
70 National Electric Code or local authority having jurisdiction | Achieve designed exhaust flow from desired locations to the outside |
| 6.6003.4c
Fan mounting | Fan outlet will be oriented toward the final termination location 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 Fan will be isolated from the building framing unless specifically designed to be directly attached Fan will be installed remotely by ducting from intake grilles | 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 |
| 6.6003.4d
Backdraft dampers (required in intermittent systems) | A
backdraft damper
Backdraft damper
A damper that allows air to flow in only one direction
will be installed between the fan and the exterior unless the system operates continuously A
backdraft damper
Backdraft damper
A damper that allows air to flow in only one direction
will be installed in any duct serving any room with a separate exhaust (e.g., dryer) | Prevent reverse air flow when the system is off Prevent spread of contaminants between rooms |
| 6.6003.4e
Combining intake ducts | All individual exhaust intake ducts will be combined on the upstream side of fan (e.g., Y-fitting, T-fitting, collector box) with the exception of dryer, kitchen, and garage | Exhaust air from desired locations to outside |
| 6.6003.4f
Duct connections | Ducts will be connected and sealed to applicable intakes, collector box, fan, and termination fitting Ducts will be connected and sealed as follows: - Round metal-to-metal or metal-to-PVC will be fastened with a minimum of three equally spaced screws
- Other metal-to-metal or metal-to-PVC connections will be securely fastened and sealed with welds, gaskets, mastics (adhesives), mastic-plus-embedded-fabric systems, or tapes
- Flexible duct-to-metal or flexible duct-to-PVC will be fastened with tie bands using a
tie band
Tie band
A strap, often made of nylon, that mechanically squeezes a flexible duct to a fitting. Must have a minimum performance temperature rating of 165° (per UL 181A-type test) and a minimum tensile strength rating of 50 pounds
tensioning tool
- PVC-to-PVC materials will be fastened with approved PVC cement
- Other specialized duct fittings will be fastened in accordance to manufacturer specifications
- In addition to mechanical fasteners, duct connections will be sealed with
UL
UL
Underwriters Laboratories
181B or 181B-M listed material
| Exhaust air from desired locations to outside 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
|
| 6.6003.4g
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 code Exception: If system operates continuously, fan housing need not be insulated | Preserve integrity of the duct system |
| 6.6003.4h
Boot to interior surface seal | Sealants will be compatible with 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 |
| 6.6003.4i
Air flow | Air flows in
CFM
CFM
Cubic feet per minute
will be measured and adjusted to meet the design requirements | Exhaust sufficient air from desired locations to outside |
| 6.6003.4j
Preventing air leakage caused by exhaust fans | Air leakage into the house from other spaces will be prevented (e.g., garages, unconditioned crawl spaces, unconditioned attics) | Ensure occupant health and safety |
| 6.6003.4k
Combustion safety | Pressure effects caused by fans will be assessed and corrected when found outside of combustion safety standards | Ensure safe operation of combustion appliances |
