Powerful kitchen range hoods like the Wolf 66-in. Pro Island can vent 1500 cu. ft. of air per minute, quickly clearing the room of smoke and cooking odors. But exhaust fans like this also can draw makeup air from unwanted sources, like chimney flues, moldy crawl spaces, and vents for fuel-burning appliances, a dangerous condition called backdrafting.

Providing makeup air has been a haphazard affair. Even companies that manufacture range hoods have not always offered much advice, or seemed unaware there was a problem, as GreenBuildingAdvisor senior editor Martin Holladay described in a blog several years ago.

This is the backdrop for the launch of Fantech’s Makeup Air System (MUAS), a through-the-wall duct kit that balances outgoing air with an equal amount of intake. Incoming air can be heated with an in-line electric heating element, and the ducted system can be installed so it sends fresh air to whatever part of the house the homeowner wants, not necessarily the kitchen.

According to Fantech, a motorized damper opens and the unit’s fan is triggered when the range hood is turned on. Fan speed is automatically synched with the exhaust system’s fan, so the amount of makeup air matches the output of the range hood. The system also can be calibrated to provide a slightly negative or slightly positive air pressure inside the house.

(A similar makeup-air system already is offered by a Minnesota company called Electro Industries. )

Three capacities and two heater options

Fantech makes three sizes, with maximum flow rates of 650, 1600, and 2000 cu. ft. per minute. That would seem to cover most if not all residential range hoods on the market.

Both the MUAS 650 and the MUAS 1600 models are vented with 12-in. metal ducts; the MUAS 2000 uses a 14-in. duct. Kits include the fan, intake wall hood, motorized shut-off damper, filter cabinet with a pleated filter, and a duct silencer. A controller matches makeup air to exhausted air to maintain the building air pressure at the level set by the installer.

In winter, range hoods jettison a lot of heated air from the house. So Fantech offers three heater options to temper incoming air. All of them run on single-phase, 240v current. According to the company, the smallest of the three, the MUAH 10/10, draws a maximum of 10,000w of electricity and produces 34,140 Btu of heat per hour. The other two, for the higher-capacity exhaust fans, draw a maximum of 20kw and produce 68,280 Btu/h.

At maximum output, the larger heaters draw 83 amps.

List prices for the fan assemblies ranged from $2158 to $3498. Heaters were priced at $1068 to $1751.