10 18-CD35D1-1
INSTALLER’S GUIDE
DUCT CONNECTIONS
Air duct systems should be installed in accordance with standards
for air conditioning systems, National Fire Protection Association
Pamphlet No. 90. They should be sized in accordance with ACCA
Manual D or whichever is applicable.
Central furnaces, when used in connection with cooling units,
shall be installed in parallel or on the upstream side of the cooling
coil to avoid condensation in the heat exchanger. With a parallel
flow arrangement, the dampers or other means used to control
flow of air shall be adequate to prevent chilled air from entering
the furnace, and if manually operated, must be equipped with
means to prevent operation of either unit unless the damper is in
full heat or cool position.
On any job, flexible connections of nonflammable material
may be used for return air and discharge connections to prevent
transmission of vibration. Though these units have been
specifically designed for quiet, vibration free operation, air ducts
can act as sounding boards and could, if poorly installed, amplify
the slightest vibration to the annoyance level.
When the furnace is located in a utility room adjacent to the
living area, the system should be carefully designed with
returns to minimize noise transmission through the return air
grille. Although these furnaces are designed with large blowers
operating at moderate speeds, any blower moving a high volume
of air will produce audible noise which could be objectionable
when the unit is located very close to a living area. It is often
advisable to route the return air ducts under the floor or through
the attic. Such design permits the installation of air return remote
from the living area (i.e. central hall).
When the furnace is installed so that the supply ducts carry air
circulated by the furnace to areas outside the space containing the
furnace, the return air shall also be handled by a duct(s) sealed
to the furnace and terminating outside the space containing the
furnace.
RETURN AIR DUCT CONNECTION
NOTE:
On upflow 5 ton airflow models where the
airflow requirement exceeds 1800 CFM - Models
will require return air openings and filters on: (1)
both sides; or (2) one side and the bottom; or (3)
just the bottom.
All return air duct systems should provide for installation of
return air filters.
1. Determine the appropriate position to set the furnace
in order to connect to the existing supply and return
ductwork.
NOTE:
Minimum return air temperature is 55° F.
2. Refer to Figure 11 and the M95 Outline Drawing for duct
connection dimensions for various furnaces.
3. The side panels on upflow furnaces include locating
notches which may be used as guides for cutting an
opening for return air. Refer to Figure 11 and the Outline
Drawings for duct connection dimensions for specific
furnace models.
4. If a 3/4" flange is to be used for attaching the air inlet duct,
add to cut where indicated by dashed lines in Figure 11.
Cut corners diagonally and bend outward to form flange.
5. If flanges are not required and a filter frame is installed,
cut along knockout guides.
6.
Upflow Furnaces:
Use the optional filter rack on either
side or on the bottom if the filter is to be used within the
furnace cabinet.
7. When the upflow furnace is installed in the horizontal
application and a return duct is attached to the top side as
shown in Figure 10, install the filter in a remote location.
Do not install the filter in the return duct directly above the
furnace in horizontal applications.
▲
WARNING
!
Do NOT install the filter in the return duct directly
above the furnace in horizontal applications. Install
the filter remotely. Installing the filter directly
above the furnace in horizontal applications may
cause property damage, serious injury or death.
▲
WARNING
!
SAFETY HAZARD
To prevent injury or death due to contact with
moving parts, turn the power to the furnace off
before servicing filters
Failure to follow the safety warnings exactly could
result in serious injury, death or property damage.
When the upflow furnace is installed in the horizontal
application and a close coupled (less than 36") return duct
is attached to the bottom side of the furnace as shown in
Figure 10, securely attach a 1/2" mesh metal hardware cloth
protective screen to the inside bottom of the filter grill to
prevent personal injury from contacting moving parts when
reaching into the return opening to replace the filter.
Close coupled (less than 36") return (filter directly beneath
bottom side return) is not recommended due to noise
considerations.
Downflow Furnaces:
Brackets must be field supplied
(Figure 12). Order BAYBRCKFLT10 2-FLR01185 for 14.5"
models, 2 -FLR01186 for 17.5", 21.5" and 24.5" models.
8. Connect the duct work to the furnace. See the M95
Outline Drawing for supply and return duct size and
location. Flexible duct connectors are recommended to
connect both supply and return air ducts to the furnace.
If only the front of the furnace is accessible, it is
recommended that both supply and return air plenums
are removable.
