Duct Connections - Trane UC SERIES Installer's Manual

Installer's Guide
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DUCT CONNECTIONS

Air duct systems should be installed in accordance with stan-
dards for air conditioning systems, National Fire Protection
Association Pamphlet No. 90. They should be sized in accor-
dance 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 units to avoid condensation in the heating element,
unless the furnace has been specifically approved for down-
stream installation. 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
which minimize noise transmission through the return air grille.
Although these winter air conditioners are designed with large
blowers operating at moderate speeds, any blower moving a high
volume of air will produce audible noise which could be objection-
able 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 contain-
ing the furnace.
Minimum return air/"air entering" temperature for the
furnace is 50° F.
Where there is no complete return duct system, the return
connection must be run full size from the furnace to a location
outside the utility room, basement, attic, or crawl space.
Do Not install return air through the back of the furnace
cabinet.
Do Not install return air through the side of the furnace cabinet
on horizontal applications.
RETURN AIR DUCT CONNECTION
All return air duct systems should provide for installation of
return air filters.
1. Set the furnace in place.
2. For side return installations on upflow models, remove the
insulation around the opening in the blower compartment.
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 10 and the outline drawing on
page 4 for duct connection dimensions for various furnaces.
4. If a 3/4" flange is to be used for attaching the air inlet duct,
add to cut where indicated by solid lines in Figure 10. Cut
corners diagonally and bend outward to form flange.
5. If flanges are not required, and a filter frame is installed,
cut along knockout guidelines.
6. Upflow furnaces: filter retainer brackets are factory
supplied for bottom return. Use the filter retainer brackets
on either side or on bottom if filter is to be used within the
furnace cabinet.
Downflow Furnaces: Brackets are factory supplied to
mount filters in the return air ductwork.
18-CD19D5-10