filter rack installed in the return-air side of the unit.
Recommended sizes for filters are shown in Table 1.
2. Avoid abrupt duct size increases and reductions. Abrupt
change in duct size adversely affects air performance.
IMPORTANT:
Use flexible connectors between ductwork and
unit to prevent transmission of vibration. Use suitable gaskets to
ensure weathertight and airtight seal. When electric heat is
installed, use fireproof canvas (or similar heat resistant material)
connector between ductwork and unit discharge connection. If
flexible duct is used, insert a sheet metal sleeve inside duct. Heat
resistant duct connector (or sheet metal sleeve) should extend
24-in. from electric heater element.
3. Size ductwork for cooling air quantity (cfm). The minimum
air quantity for proper electric heater operation is listed in
Table 2. Heater limit switches may trip at air quantities
below those recommended.
NOTE:
A 90-degree elbow must be provided in the supply
ductwork to comply with UL (Underwriters’ Laboratories) codes
for use with electric heat.
4. Insulate and weatherproof all external ductwork. Insulate
and cover with a vapor barrier all ductwork passing through
conditioned spaces. Follow latest Sheet Metal and Air
Conditioning
Contractors
National
Association
(SMACNA) and Air Conditioning Contractors Association
(ACCA) minimum installation standards for residential
heating and air conditioning systems.
5. Secure all ducts to building structure. Flash, weatherproof,
and vibration-isolate duct openings in wall or roof accord-
ing to good construction practices.
V.
RIG AND PLACE UNIT
Use spreader bars or crate top when rigging the unit. The units
must be rigged for lifting as shown in Fig. 7. Use extreme caution
Fig. 6— Roof Curb Dimensions
ODS CATALOG NUMBER
A
IN. (MM)
Flat
Curb
CPRFCURB001A00
8 (203)
CPRFCURB002A00
11 (279)
CPRFCURB003A00
14 (356)
C95007
—6—
