Multiport Exhaust Fan Serving Multiple Dwellings

Select a fan that:

has an electrically commutated motor (ECM) and/or utilizes (VFD) controllers

is capable of maintaining a minimum operating static pressure of .25 inches of water column or greater

motors 1 horsepower or larger must meet NEMA premium efficiency standards

motors less than 1 HP must be rated by the Home Ventilation Institute to satisfy these requirements

Terminate exhaust system to the outdoors, which does not include unconditioned spaces such as attics and crawl spaces that are ventilated with the outdoors

Install terminations: A minimum of 3' away from any property line; A minimum of 3' away from operable opening to houses; A minimum of 10' away from mechanical intake; Above the snow-line.

If the termination is at the soffit, seal soffit vents within 6' of the termination

Install corrosion resistant screen, louver, or grille material over exterior termination with a hole size of no less than 1/4" and no greater than 1/2" in any direction

Design one or more exhaust fans located upstream of all the exhaust inlets to run continuously, or install a system of one or more backdraft dampers to isolate each dwelling unit from the common duct when the fan is not running

Install all electrical wiring according to manufacturer specifications and applicable code

Mount fan using mechanical fasteners per manufacturer's specifications and applicable code (e.g., seismic restraints)

Isolate unit from the building framing unless specifically designed to be directly attached

If combining ducts, combine them on the upstream side of fan using "Y"-fittings or collection boxes

Do not combine dryer, kitchen, or garage exhausts streams with any other exhaust stream

Seal all air moving portions of the system using UL 181 products without interfering with the function of dampers

Ensure fan and service disconnect switch are accessible for maintenance according to NEC, or applicable building code

If fire dampers are required in the fresh air supply duct, install them according to applicable building code

Fire dampers must be accessible for inspection and/or testing

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

Adjust fan speed, dampers, and registers until design specifications are met