Page 20
Installer’s Information Manual
Table 5. Bottom Closure Part Numbers.
GAS
INPUT*
(Btu/Hr)
MOTOR*
HORSE-
POWER.
BOTTOM CLOSURE
PART NUMBER
40,000
60,000
1/4, 1/3
1/4, 1/3
4045900
60,000 1/2
4045901
80,000 1/4,
1/3
4045900
80,000 1/2
4045901
80,000 3/4
4045902
100,000 1/3,
1/2
4045901
100,000
120,000
3/4
1/2, 3/4
4045902
140,000 3/4,
3/4
4045903
* GAS INPUT and MOTOR HP can be found on furnace
rating plate.
WARNING
: Failure to install bottom closure panel
could allow combustion products to enter circulating air
stream, resulting in injury or death by asphyxiation.
Downflow installations use top return or top and side return.
Horizontal installations use end return or end and top
return.
In upflow position, return air duct must be a minimum depth
of 23-31/32 inch. See Figure 23.
Figure 23. Bottom Filter Cabinet
In downflow position, return air duct must be a minimum 19-
7/8 inch inside depth. See Figure 24.
NOTE: A combustible floor base, available from the
manufacturer, is required for downflow furnace installation
on wood flooring. See Section 5, "Allowing For
Clearances."
Figure 24. Downflow Filter Application
DUCT DAMPERS
You may balance airflow with dampers installed in each
branch run duct and adjust for even temperature throughout
the heated space. For proper furnace operation, make
sure:
•
Supply air registers and return air grilles are open;
•
Rugs, carpets, drapes or furniture are clear of registers
and grilles;
•
Size and shape of supply air plenum is correct;
•
Number of supply air ducts is correct.
LOCATION OF COOLING COIL
If furnace will share common duct system with a separate
cooling unit, install furnace parallel to or upstream of
cooling unit. This avoids condensation in heating element.
Do not install cooling coil in return air ductwork. With
parallel flow, dampers or other means must prevent chilled
air from entering furnace. If dampers or other means are
not in full heat or cool position, furnace or cooling unit must
not operate.
SECTION 13. SELECTING AND
INSTALLING FILTER CABINETS
Properly installed air filters keep blower motor, blower
wheel and cooling coil (if installed) clean. Filters and filter
cabinets are not supplied with this furnace because of its
