Page 24
Installer’s Information Manual
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
of the following:
??
Supply air registers and retu rn air grilles are open;
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Rugs, carpets, drapes or fu rniture are clear of registers
and grilles;
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Size and shape of supply air plenum is correct;
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Number of supply air ducts is correct.
LOCATION OF COOLING COIL
If furnace will share common duct system with a separate
cooling unit, install fu rnace parallel to or upstream of
cooling unit. This avoids condensation in heating element.
Do not install cooling coil in retu rn-air ductwork. With
parallel flow, dampers must be installed to prevent chilled
air from entering fu rnace. If dampers are not in full heat or
full cool position, fu rnace or cooling unit must not operate.
SECTION 10. SELECTING AND
INSTALLING FILTERS
Properly installed air filters keep blower motor, blower
wheel and cooling coil (if installed) clean. Filters and filter
mounting hardware are not supplied with this fu rnace.
Filter system must be field supplied. The manufacturer has
downflow filter kits available.
This furnace was designed for exte rnal filters. Do not
install air filters inside fu rnace casing. Obtain and install
proper filter frames and correctly sized filters. To inspect,
clean or replace air filters, follow the instructions in the
User’s Information Manual.
CAUTION: You must install air filters to keep blower motor,
blower wheel and cooling coil (if installed) clean. Dirty
equipment may reduce system efficiency or cause erratic
control performance and can result in damage to blower
motor, heat exchanger or air conditioner (if installed).
Follow these instructions for minimum size and quantity
recommendations. Air velocity must not exceed 300 feet
per minute through low velocity disposable filters. Air
velocity must not exceed 650 feet per minute through high
velocity washable filters. Undersized filters reduce airflow
and can adversely affect furnace and cooling system
operation.
FILTER MOUNTING
Use a downflow filter kit, field fabricated filter cabinet, or a
return-air filter grille. Field fabricated filter cabinets should
allow spacing between filter and fu rnace. Placing a field-
supplied filter directly against fu rnace will decrease airflow
and adversely affect furnace operation.
When using manufacturer’s downflow filter kit, filters must
be at least 16” X 20” X 1”, high-velocity, washable filters
(included in kit). See Figure 28.
See Table 6 for minimum recommended filter size for field
fabricated filter cabinets or return-air filter grille.
Table 6. Minimum Recommended Filter Size (inches).
GAS
INPUT*
(Btu/hr)
MOTOR*
HORSE-
POWER
DISPOSABLE
AIR FILTER
- two required
HIGH-
VELOCITY
WASHABLE
AIR FILTER
54,000
1/3
16 X 25 X 1
16 X 25 X 1
72,000
1/2
16 X 25 X 1
16 X 25 X 1
90,000
1/2
16 X 25 X 1
16 X 25 X 1
72,000
3/4
20 X 25 X 1
20 X 25 X 1
90,000
3/4
20 X 25 X 1
20 X 25 X 1
108,000
3/4
20 X 25 X 1
20 X 25 X 1
126,000
3/4
20 X 25 X 1
20 X 25 X 1
* GAS INPUT and MOTOR HP can be found on furnace
rating plate.
SECTION 11. CHECKS BEFORE
STARTING FURNACE
Before starting furnace for the first time, be sure you can
answer "Yes" to each of these questions:
1. Is furnace properly equipped to operate with available
fuel?
2. Is furnace level or tilted forward within 1/4 inch from
front to back?
3. If Downflow, is furnace level within 1/4 inch from side to
side?
4. If Horizontal, is furnace level or tilted toward burner up
to 1/4”.
5. Have you cleared away all loose construction and
insulation materials?
6. Is furnace installed with proper clearances?
7. If furnace is in a crawl space, is it sufficiently elevated
above the ground.
8. Does fu rnace have sufficient combustion and
ventilation air?
9. Is the vent system sloped toward the fu rnace at least
1/4 inch per foot?
10. Have you checked the vent system for leaks?
11. Did you completely check gas pipe and controls for gas
leaks?
12. Does electrical wiring follow current National Electrical
Code ANSI/NFPA 70 or Canadian Electrical Code CSA
C22.1 as well as local codes?
13. Is furnace electrically grounded?
14. Is room thermostat properly installed and heat
anticipator set correctly?
15. Is duct system correctly sized and sealed?
16. Are air filters in place and correctly sized?
