You asked, we answered

Q: Why do I need Makeup Air for kitchen exhaust over 400 cfm?

A: Todays’ homes are built tight. A large exhaust hood range will depressurize the home causing all sorts of unwanted things: untreated air affects indoor air quality; negative pressure in home that pulls solid gases; backdrafting.

Q: I have a 600 cfm kitchen exhaust fan, do I need Makeup Air?

A: Yes. The Code mandates that Makeup Air be supplied for kitchen exhaust hood fans over 400 cfm and that the MUA be approximately equal. Think balanced ventilation always, i.g. 600 cfm out – 600 cfm in. That’s easy!

Q: Why can’t I just open an outside window or door?

A: Technically this would work, however, your weather outside better be mild and dry. Winter and summer seasons will prove taxing on your heating or cooling bill by just leaving doors or windows open. If that’s the solution, then why build efficient in the first place? Controlling what comes through that opening isn’t feasible. Contaminants of all types can breeze in for a visit.

Q: My contractor just wants to use a passive damper. Will that work?

A: In most cases, ONE single damper is not sufficient. To pull air through a hole it has to be sucked by depressurizing the inside space. The amount of air through the hole depends on the size of the hole and the amount of negative pressure inside to pull it in. The smaller the hole the greater depressurization required. You contractor may suggest multiple dampers which means multiple openings in your home. This concept leads to energy inefficiencies, or a “Swiss cheese building envelope”.

Q: Will the Fantech MUAS work with my hood?

A: The Fantech makeup Air System will work with any other manufacturer’s hood exhaust systems. i) As long as the hood exhaust is 120/240V, 60 Hz. ii) Size the MUAS for the same airflow (CFM) as the hood exhaust.

Q: Where does kitchen makeup air have to be supplied to?

A: • The Code says you have to supply the MUA into the space that it is exhausted from (kitchen), or to a space or duct system that connects to the kitchen through permanent openings (no closed doors). Such permanent openings shall be the same or greater than the openings that supply the MUA.

Q: Can I install a MUAS in an uninsulated attic/basement?

A: Yes! Simply insulate the ductwork to the R value required for your area.

Q: In cold climates do I have to have a heater?

A: A heater is recommended to condition the MUA into the home so that the cold raw outside air is tempered before entering the space.


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