MODELS MUA006A • MUA008A • MUA010A
Page 9
FREQUENTLY ASKED
QUESTIONS (FAQS)
1. What does an automatic make-up air
damper do?
An automatic make-up air damper (the “Damper”) provides a pathway for
fresh air to enter a home from outdoors when a compatible range hood is
operating. When the hood blower is operating The Damper opens thereby
creating a known, controlled point for fresh air to enter the home while air
is being exhausted from the building by the range hood.
By operating in this manner, the Damper provides two key benefits for the
home:
• It facilitates air exchange between indoors and outdoors, by helping to
allow fresh air into the home to replace air which is exhausted out of
the home.
• By allowing fresh air into the building when a compatible exhaust device
is on, the Damper helps to avoid negative pressure conditions within
the home which may interfere with the proper operation of combustion
equipment within the home.
Overall, the Damper lets your range hood do its job more effectively and
without interfering with the proper operation of other home systems.
2. Which automatic make-up air damper do I need?
The required amount of make-up air will vary for each home and the
amount of exhaust ventilation provided within the home. As a general rule
of thumb, Zephyr recommends sizing the make-up air damper as follows:
- One 6” damper for ventilation rated up to 600 CFM
- One 8” damper for ventilation rated up to 1000 CFM
- One 10” damper for ventilation rated up to 1200 CFM
However, Zephyr highly recommends that a qualified professional HVAC
contractor be consulted after installation to ensure there is no negative
pressure in the home when the range hood is operating. If negative
pressure exists, then additional make-up air should be added.
3. Does the “Damper” provide combustion air for combustion
appliances like a water heater or
a furnace?
No. The Damper helps to replace air which is exhausted by a compatible
range hood. But it does NOT help to replace air which is drawn from the
indoors by a combustion appliance like a natural gas water heater, and it
should not be relied upon to perform this function. One main reason for
this restriction is that the Damper is only open when the range hood that
it’s connected to is operating. So there is no assurance that the Damper
would be open when other appliances, like a water heater, are operating.
Other means must be provided to ensure adequate combustion air for
these appliances.
4. How do I know if I need make-up air for my
range hood?
In some cases the local building code may tell you that make-up air is
necessary. For example, some codes specify that range hoods with
exhaust flows of 300 cubic feet per minute (CFM) or higher need a
mechanical system to introduce make-up air.
In other cases, make-up air for a range hood is desirable regardless of
whether code requires it. This is especially true for:
• larger range hoods (those over 300 cfm)
• homes which are well air-sealed
• homes with atmospherically vented combustion appliances (i.e. a
water heater or natural draft fireplace), which are more susceptible to
improper venting if depressurization occurs.
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.
5. What are the benefits of providing make-up air to replace air
which is exhausted out of the home by a range hood?
Range hoods are designed to pull out pollutants like cooking odors or
moisture 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 “new” 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 exhaust a lot more air than can
be replaced through normal cracks in the building shell.
By providing an intentionally designed opening for fresh air to replace
air which is exhausted out by the range hood, several important benefits
result:
• The make-up air entering the home comes in at a known point, where
it is also filtered
• Negative pressure conditions, which could arise if air is exhausted from
a home without being replaced by new fresh air, are prevented
• Pollutants are more effectively exhausted from the home while fresh
replacement air is drawn into the home, improving ventilation
6. Does ASHRAE 62.2-2007 – “Ventilation and Acceptable Indoor
Air Quality in Low-Rise Residential Buildings” – require the use
of a make-up air damper?
ASHRAE 62.2-2007 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 limited. For example, Section 6.4 of the standard
limits the net exhaust flow from a home’s two largest exhaust appliances
if the home has atmospherically vented or solid-fuel burning appliances
located within the pressure boundary of the house. This standard is
available at www.ashrae.org.
7. Can I use the Zephyr Automatic Make-Up Air Damper with other
equipment in my home?
No. The Zephyr Automatic Make-Up Air Damper may only be used with
compatible Zephyr range hoods over 400 CFM.
8. What are the different ways that the Damper can be installed in
my home?
The most common way to install the Damper is to connect it to a home’s
central duct system. In this application, outside fresh air enters the home
through the Damper and is then routed and distributed through the home’s
ducts.
9. What happens after a power outage?
The Damper system and the associated exhaust devices will not lose their
settings following a power outage. So the system will resume its normal
operation following a power outage, based on the settings it used prior to
the outage.
Regular maintenance is necessary to ensure the proper operation
of the Damper system. Failure to conduct such routine maintenance
can jeopardize the ability of the Damper to introduce fresh air into the
home. Regular maintenance should include the following activities:
• Clean the outside bird screen to ensure it is free from debris and
open to allow fresh air to enter.
• Clean or replace the interior filter(s) which serve to filter fresh air
before it enters the home.
• Maintain a clear opening at the outdoor end cap, which means pre
-
venting the buildup of snow, leaves, or vegetation at the end cap.
• During regular HVAC maintenance, have the mechanical contrac
-
tor inspect the Damper system for proper operation.
MAINTENANCE
