Best MD8T Installation manual

AUTOMATIC

MODELS MD6T • MD8T

Page 1

MAKE-UP AIR DAMPER
WITH TRANSFORMER

READ AND SAVE THESE INSTRUCTIONS

FOR RESIDENTIAL USE ONLY

WARNING

TO REDUCE THE RISK OF FIRE, ELECTRIC SHOCK, OR
INJURY TO PERSONS, OBSERVE THE FOLLOWING:

1. Installation work and electrical wiring must be done by a qualified
person(s) in accordance with all applicable codes and standards,
including fire-rated construction codes and standards.

2. Do not use the unit in conjunction with any exhaust device other
than compatible BEST or Broan range hoods.

3. This unit is not designed to provide combustion air for fuel­burning appliances.

4. Do not connect the unit directly to a combustion appliance of
any type.

5. Sufficient air is needed for proper combustion and exhausting
of gases through the flue (chimney) of fuel burning equipment
to prevent backdrafting. Follow the heating equipment
manufacturer’s guideline and safety standards such as those
published by the National Fire Protection Association (NFPA),
and the American Society for Heating, Refrigeration and
Air Conditioning Engineers (ASHRAE), and the local code
authorities.

6. Before servicing or cleaning unit, switch power off at service
panel and lock the service disconnecting means to prevent
power from being switched on accidentally. When the service
disconnecting means cannot be locked, securely fasten a
prominent warning device, such as a tag, to the service panel.

7. When performing installation, servicing or cleaning the unit, it is
recommended to wear safety glasses and gloves.

8. During extreme weather events including snow storms,
that

the intake area for the outside air duct is not blocked and
able to provide a clear pathway for outside air to enter the
system.

9. When cutting or drilling into wall or ceiling, do not damage
electrical wiring or other hidden utilities.

10. When notching or drilling into framing including floor supports,
rim joists, and wall studs, comply with code and manufacturer
limitations on allowable modifications to these structural
members.

11. This unit is intended to be installed within the home in a location
protected from moisture.

12. This unit must be in an accessible location which allows for
inspection of the unit.

13. Use this unit only in the manner intended by the manufacturer.
If you have questions, contact the manufacturer at the address
or telephone number listed in this document.

14. When federal, provincial or state legislation comprises more
restrictive installation and/or certification requirements, the
aforementioned requirements prevail on those of this document
and the installer agrees to conform to these at his own expense.

ensure

To register this product

visit: www.broan.com

CAUTION

1. D o not locate outside air inlet near hazardous materials or explosives.

2. Unit shall not be installed to introduce air from crawlspaces, garages,
attics, adjacent dwelling units, or other locations within the building
shell. Unit shall be installed to introduce air directly from outdoors.

3. Do not run the outside air duct directly above or closer than 2 ft to
any furnace or its supply plenum, boiler, or other heat producing
appliance.

4. Any ductwork used in conjunction with the Damper must be installed
in compliance with all local and national codes that are applicable.

5. Do not operate the Damper for fresh air introduction until all system
filters, including the central duct system filter, have been installed per
the system design.

6. Please read the unit specification label on the product for further
information and requirements.

7. The Damper’s outdoor air intake, ducting, and any filters should be
inspected and maintained on a regular basis.

8. Insulate the duct and damper to prevent build-up of condensation in
cold weather climates. Vapor barriers on both sides of insulation are
recommended.

WARRANTY

Broan-NuTone warrants to the original consumer purchaser of its products that such products
will be free from defects in materials or workmanship for a period of one year from the date of
original purchase. THERE ARE NO OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING,
BUT NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE.

During this one-year period, Broan-NuTone will, at its option, repair or replace, without charge,
any product or part which is found to be defective under normal use and service.

THIS WARRANTY DOES NOT EXTEND TO FLUORESCENT LAMP STARTERS AND TUBES. This
warranty does not cover (a) normal maintenance and service or (b) any products or parts which
have been subject to misuse, negligence, accident, improper maintenance or repair (other than by
Broan-NuTone), faulty installation or installation contrary to recommended installation instructions.

The duration of an implied warranty is limited to the one-year period as specified for the express
warranty. Some states do not allow limitation on how long an implied warranty lasts, so the above
limitation may not apply to you.

BROAN-NUTONE’S OBLIGATION TO REPAIR OR REPLACE, AT BROAN-NUTONE’S OPTION,
SHALL BE THE PURCHASER’S SOLE AND EXCLUSIVE REMEDY UNDER THIS WARRANTY.
BROAN-NUTONE SHALL NOT BE LIABLE FOR INCIDENTAL, CONSEQUENTIAL OR SPECIAL
DAMAGES ARISING OUT OF OR IN CONNECTION WITH PRODUCT USE OR PERFORMANCE.
Some states do not allow the exclusion or limitation of incidental or consequential damages, so
the above limitation may not apply to you.

This warranty gives you specific legal rights, and you may also have other rights, which vary from
state to state. This warranty supersedes all prior warranties.

To qualify for warranty service, you must (a) notify Broan-NuTone at the address or telephone
number below, (b) give the model number and part identification and (c) describe the nature of
any defect in the product or part. At the time of requesting warranty service, you must present
evidence of the original purchase date.

Broan-NuTone LLC Hartford, Wisconsin www.broan.com 800-558-1711

BROAN-NUTONE ONE YEAR LIMITED WARRANTY

PLAN THE INSTALLATION

Planning the installation first requires selecting the most appropriate
installation approach. The chart below offers suggestions for the most
effective installation approach by considering a few important factors.
Further details on the two main types of installations are provided below.

MODELS MD6T • MD8T

Page 2

• Outside air intake is placed high enough above grade to prevent
blockage from snow or other debris such as leaves, and at a mini­mum of 1’ above grade.

• Make-up air damper should not draw air from crawlspaces, ga­rages, attics, adjacent dwelling units, or any enclosed part of the
building. The Damper should be installed to draw air directly from
outdoors.

• House has central duct work?

Yes

• Return-air side of duct work is
accessible -either the return-air trunk

Yes

Damper connected to

return side of central

duct system

or return- air plenum?

No

No

Damper ducted directly

to a ceiling, floor, or wall

register

OUTSIDE AIR INTAKE LOCATION

Proper design and location of the outside air intake location is critical in
ensuring that the Damper can safely and reliably provide an opening for
fresh air to enter the home. The following requirements for the location
of the outside air intake must be met:

• Outside air intake is located a minimum of 10’ from combustion ap­pliance vents, chimneys, plumbing stacks, and bathroom or kitchen
exhaust vents. If local codes have more stringent separation re­quirements, they shall apply.

TYPICAL INSTALLATIONS

OUTSIDE AIR INTAKE OPENING PROTECTION

Because the Damper, together with the end cap and outside air duct
which are installed with it, will allow outdoor air into the indoor environ­ment, it is important to meet the following requirements:

• Model 641FA (6”) and 643FA (8”) fresh air inlet wall caps include
protective bird screens to keep out animals and outside debris.
Clean screens often and do not remove.

• If a protective bird screen other than the screen provided is used, it
must cover the entire opening of the

outside air duct. This screen

must also have openings of at least ¼” but no larger than ½ ”.

• The outdoor air intake opening should meet local code provisions
for the protection of openings in exterior walls, including steps to
prevent moisture intrusion around the opening.

Note that the screen over the outside air opening is not a filter. It is
intended to prevent the intake of leaves, animals, or debris into the out­side air duct. A downstream filter is necessary to remove pollen, dust,
and other airborne particles. Potential filter locations are shown below
in the Typical Installations section.

MINIMUM RETURN AIR TEMPERATURE REQUIREMENTS

HVAC equipment manufacturers may have minimum requirements for
the air temperature in the return air plenum. Introducing outdoor air to
the return side of the central duct system may impact this temperature.
The installer should adjust both the size of the outside air duct and the
location of its connection to the return side of the central duct system in
a manner so that minimum air temperature requirements are satisfied
under design conditions.

Installations will vary according to the location in the home where the unit is installed and which model Damper is used. Use the following
illustrations and notes as guidance for your own installation. Always comply with local code requirements and in any instance where a detail
shown below conflicts with local code, the local code provision shall apply.

CENTRAL SYSTEM SUPPLY AIR

THERMOSTAT

HEATING APPARATUS

AIR DISTRIBUTION FAN

COOLING APPARATUS

AIR HANDLER UNIT

EXTERIOR WALL

CENTRAL SYSTEM RETURN AIR

INSULATED OUTSIDE
AIR DUCT (slope toward wall cap)

FRESH AIR INLET WALL CAP
WITH BIRD SCREEN

VENTILATION AIR INTAKE
(locate away from pollutant sources)

FIELD MEASUREMENT OF OUTSIDE
AIR DUCT PRESSURE. (See “Install The
Damper” section on page 3 for damper
balancing instructions.)

AUTO. MAKE-UP AIR DAMPER

REGISTER BOX ADAPTED
WITH SLIDE-IN FILTER (optional)

FURNACE FILTER

Damper connected to return side of central duct system.

EXTERIOR WALL

MODELS MD6T • MD8T

Page 3

INTERIOR WALL

WALL
REGISTER

Damper and outside air duct connected directly to a ceiling, floor, or wall register.

INSTALL THE DAMPER

TO CENTRAL SYSTEM
RETURN AIR OR INTERIOR
WALL REGISTER

AIR FLOW AIR FLOW

DAMPER FLAP (Install in
vertical position shown.)

SET SCREW

OUTSIDE AIR

MAKE-UP AIR

DAMPER

CONTACT CONNECTIONS ON

GRD

120 VAC
60 HZ

INSULATED OUTSIDE
AIR DUCT (slope toward wall cap)

WALL CAP WITH
BIRD SCREEN

VENTILATION AIR INTAKE
(locate away from pollutant sources)

FIELD MEASUREMENT OF OUTSIDE
AIR DUCT PRESSURE. (See “Install The
Damper” section on page 3 for damper
balancing instructions.)

MOTORIZED DAMPER

REGISTER BOX ADAPTED
WITH SLIDE-IN FILTER (optional)

MODEL QP3 SERIES
MAKE UP DAMPER CONNECTION
(switched low voltage)

20 GAUGE BELL WIRE TO

BACK OF HOOD

24V

TRANSFORMER

(included)

HOOD

Install the damper as shown. Make sure damper flap is in a vertical
position when closed and power is off. The set screw can be used
to adjust the damper opening - thereby balancing the inside and
outside air pressure when the range hood exhausts at high speed.

Wire the system as shown.

MAKE-UP AIR

DAMPER

24V

TRANSFORMER

MODEL E60000 SERIES & E64000 SERIES

MAKE-UP AIR DAMPER CONNECTION

(switched high voltage)

WHT

WHT WHT

ORG

WHT

BLK

BLK

24V

(included)

BLK

BLK

GRD

120 VAC
60 HZ

HOOD

SYSTEM OPERATION

Once the Damper and the associated Broan or BEST exhaust
devices are installed, the installer should confirm that the Damper
opens and closes in conjunction with signals from the exhaust
devices(s) as intended.

A qualified HVAC contractor should also ensure the proper
operation and venting of all combustion equipment in the home.

MAINTENANCE

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
preventing the buildup of snow, leaves, or vegetation at the end
cap.

• During regular HVAC maintenance, have the mechanical contrac­tor inspect the Damper system for proper operation.

MODELS MD6T • MD8T

Page 4

FREQUENTLY ASKED
QUESTIONS (FAQS)

1. What does the Broan Automatic Make-Up Air
Damper do?

The Broan Automatic Make-Up Air Damper (the “Damper”) provides
a pathway for fresh air to enter a home from outdoors when a
compatible exhaust device is operating. The Damper opens when
a compatible BEST or Broan range hood is operating, 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 let’s your Broan or BEST exhaust devices do
their job more effectively and without interfering with the proper
operation of other home systems.

2. 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

drawn fr

is
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.

3. How do I know if I need make-up air for my

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 - so outside air may not be able

• homes with atmospherically vented combustion appliances

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.

om the indoors by a combustion appliance like a natural

range hood?

to easily find its way into the home through cracks, to replace air
which is exhausted out

(i.e. a water heater or natural draft fireplace), which are more
susceptib
the home.

le to improper venting if depressurization occurs in

4. 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
are prevented

• Pollutants are more effectively exhausted from the home
while fresh replacement air is drawn into the home, improving
ventilation

5. Does ASHRAE 62.2-2007 – “Ventilation and
Acceptable Indoor Air Quality in Low-Rise
Residential Buildings” – require the use of a make­up 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.

6. Can I use the Broan Automatic Make-Up Air Damper
with other equipment in my home?

No. The Broan Automatic Make-Up Air Damper may only be used
with compatible BEST or Broan range hoods. More information on
exact models of the Damper and compatible exhaust devices can
be found in the Broan Automatic Make-Up Air Damper Application
Guide.

7. 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. More information on this
installation approach can be found in the Broan Automatic Make­Up Air Damper Application Guide

web site: www.broan.com.

on our

8. What if my home doesn’t have ducts?

Homes without ducts can still utilize the Damper to help replace
air which is exhausted from the home by the range hood. An
installation illustration for this situation is included in the Broan
Automatic Make-Up Air Damper Application Guide on our web site:
www.broan.com.

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.

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