Selection Guide

When a fan exhausts air from a home an equal
amount of air must enter the home. The air entering
the home is called makeup air. Because today’s
homes are built to be “tighter” and more energy-
efficient, they inherently resist the infiltration of
outdoor air through the home's exterior. A home's
tightness limits the amount of makeup air it will
permit. In other words, even a powerful exhaust
fan can only exhaust as much air as the home
permits via makeup air infiltration. When an
exhaust fan is operated at a speed that exceeds a
home's ability to make up the air via infiltration a
couple of undesirable symptoms occur.
One of the most noticeable symptoms of
inadequate makeup air is when a properly-sized
kitchen exhaust hood doesn’t remove smoke
and odor in a timely manner. Cooking-generated
smoke is a very visible example of this. Opening
a window provides the necessary infiltration to
let the exhaust fan do its job, and the kitchen is
quickly cleared of smoke via the kitchen hood. The
necessity of opening a window in order to operate
the kitchen exhaust hood is hardly ideal, however.
Another symptom is often not as visible, but
presents a greater danger to occupants. Fuel-
burning appliances (such as furnaces and water
heaters) as well as fireplaces utilize vent/chimney
systems to discard products of combustion out
of the home. When an exhaust fan doesn’t have
adequate makeup air, a negative pressure is
created inside the home. A small amount of
negative pressure can cause “back-drafting”
of vent/chimney systems, which results in the
accumulation of hazardous combustion products in
the home. Products of combustion include carbon
monoxide, which is invisible and odorless. It’s
no secret that a potential back-drafting situation
should be avoided without exception.
Fantech’s Makeup Air System solves this problem
by providing an equal amount of makeup air into
the home while the exhaust fan is operating. The
makeup air system’s controls ensure the amount of
makeup air EXACTLY matches the exhaust amount,
regardless of the exhaust fan’s speed. In addition
to allowing the exhaust system to run at intended
capacity and eliminating associated negative
pressure, the makeup air system allows for the
makeup air to be managed. Since the makeup
air is fan-forced, it can be filtered, tempered, and
routed via duct work to a desirable location for
delivery into the home.
As if functionality and safety aren’t reason enough,
the building code requires makeup air for many
applications.
7
1
Exhaust Makeup Air System
What goes out, must come in - so says the building code
fantech
Wall Intake Hood, FML
Fast Clamp, FC
1
2
3
4
Shut-off Damper, ADC
Filter Cassette, FGR
8
Makeup Air Fan, FG EC
Silencer
1
, LD
5
6
7
8
Inline Duct Heater
1
, EM-WX
Controller, FMAC
1
optional
6
5
3
2
4
2
2
2