Make-Up Air Application Guide

Broan Automatic Make-Up Air Damper Product Guide – 04-17-13 19
In homes with any one of these factors make-up air is advised. And in homes with more
than one of these conditions, make-up air for the range hood is strongly advised.
4. What are the benefits of providing make-up air to replace air which is exhausted
out of the home by a range hood or bathroom exhaust fans?
Exhaust fans in a home are designed to pull out pollutants like cooking odors or moisture
from a shower at the source, so they don’t linger in the home. Because these fans pull
air out of the house, this air needs to be replaced with “fresh” air from outdoors. Normally
this make-up air enters the home through cracks and holes in the “shell” of the building.
But modern homes are air-sealed much more thoroughly so there are not as many
cracks and openings. Plus some exhaust fans like range hoods may be designed to
exhaust more air than can be replaced through normal cracks in the building shell.
By providing an intentionally designed opening for fresh outdoor air to replace air which
is exhausted by the range hood or bath exhaust fans, several important benefits result:
‐ A larger amount of the make-up air entering the home comes in at a known point,
where it can also be filtered
‐ The severity of negative pressure conditions, which could arise if air is exhausted
from a home without being replaced by fresh outdoor air, are reduced
‐ Pollutants are more effectively exhausted from the home while fresh outdoor air
is drawn into the home, improving ventilation
5. Does ASHRAE 62.2 – “Ventilation and Acceptable Indoor Air Quality in Low-Rise
Residential Buildings” – require the use of a make-up air damper?
ASHRAE 62.2 does not specifically require make-up air dampers. In a few limited
circumstances, this standard does require that net exhaust flows from a house be either
limited or that make-up air be provided. For example, Section 6.4 of the standard limits
the net exhaust flow from a home’s two largest exhaust appliances, or requires make-up
air to be provided, if the home has natural draft vented or solid-fuel burning appliances
located within the pressure boundary of the house. This standard is available at
www.ashrae.org
.
6. Can I use the Broan Automatic Make-Up Air Damper with other equipment in my
home?
The Broan Automatic Make-Up Air Damper is approved for use with compatible Broan,
BEST, or NuTone range hoods or exhaust fans. Unless specifically noted, Broan does
not warrant proper operation of the Damper if used in conjunction with other brands of
exhaust devices. None of the Damper models should ever be used to provide
combustion air for combustion appliances. More information on various models of the
Damper and compatible exhaust devices can be found in the Make-Up Air Specifier on-
line tool and in the individual Broan Automatic Make-Up Air Damper specification sheets.