20
18-CD19D7-22
Installer’s Guide
TABLE 15
Orifice
Twist Drill
Size If
Installed
At Sea
Level
ALTITUDE ABOVE SEA LEVEL
and Orifice Required At Other Elevations
2000 3000 4000 5000 6000 7000 8000 9000 10000
42
43
44
45
46
47
42
44
45
46
47
48
43
44
45
47
47
48
43
44
45
47
47
49
43
45
46
47
48
49
44
45
47
48
48
49
44
46
47
48
49
50
45
47
48
49
49
50
46
47
48
49
50
51
47
48
50
50
51
52
54
55
56
57
58
54
55
56
58
59
55
55
56
59
60
55
55
57
59
60
55
56
57
60
61
55
56
57
60
62
55
56
58
61
62
56
56
59
62
63
56
56
59
63
63
56
57
60
63
64
From National Fuel Gas Code - Table F-4
TABLE 16
FINAL MANIFOLD PRESSURE
SETTINGS (inches w.c.)
FUEL
PRESSURE
NATURAL GAS
3.5" W.C.
LP GAS
10.5" W.C.
LIGHTING INSTRUCTIONS
▲
WARNING
!
DO NOT attempt to manually light the burner. Failure to
follow this warning could result in property damage,
personal injury or death.
Lighting instructions appear on each unit. Each
installation must be checked out at the time of initial
start up to insure proper operation of all components.
Check out should include putting the unit through
one complete cycle as outlined below.
Turn on the main electrical supply and set the thermostat
above the indicated temperature. The ignitor will automati-
cally heat, then the gas valve is energized to permit the flow
of gas to the burners. After ignition and flame is established,
the flame control module monitors the flame and supplies
power to the gas valve until the thermostat is satisfied.
TO SHUT OFF
For complete shutdown: Move the control switch on the main
gas valve to the “OFF” position (See Figures 27 and 28, page
19). Disconnect the electrical supply to the unit.
▲
CAUTION
!
If this is done during the cold weather months, provisions
must be taken to prevent freeze-up of all water pipes and
water receptacles. Failure to follow this warning could
result in property damage.
Whenever your house is to be vacant, arrange to have
someone inspect your house for proper temperature.
This is very important in below freezing weather. If
for any reason your furnace should fail to operate
damage could result, such as frozen water pipes.
CONTROL AND SAFETY SWITCH
ADJUSTMENT
LIMIT SWITCH CHECK OUT
The limit switch is a safety device designed to close the gas
valve should the furnace become overheated. Since proper
operation of this switch is important to the safety of the unit,
it
must be checked out on initial start up by the
installer
.
To check for proper operation of the limit switches, set the
thermostat to a temperature higher than the indicated
temperature to bring on the gas valve. Restrict the airflow
by blocking the return air or by disconnecting the blower.
When the furnace reaches the maximum outlet temperature
as shown on the rating plate, the burners must shut off. If
they do not shut off after a reasonable time and overheating
is evident, a faulty limit switch is probable and the limit
switch must be replaced. After checking the operation of the
limit control, be sure to remove the blockage from the return
air inlet, or reconnect the blower.
AIRFLOW ADJUSTMENT
Check inlet and outlet air temperatures to make sure they
are within the ranges specified on the furnace rating name-
plate. If the airflow needs to be increased or decreased, see
the wiring diagram (in Service Facts) for information on
changing the speed of the blower motor.
▲
WARNING
!
Disconnect power to the unit before removing the blower
door. Failure to follow this warning could result in property
damage, personal injury or death.
This unit is equipped with a blower door switch which cuts
power to the blower and gas valve causing shutdown when
the door is removed. Operation with the door removed or
ajar can permit the escape of dangerous fumes. All panels
must be securely closed at all times for safe operation of the
furnace.
NOTE: Direct drive motors have bearings which are
permanently lubricated and under normal use, lubrica-
tion is not recommended.
INDOOR BLOWER TIMING
The control module controls the indoor blower. The blower
starts approximately 45 seconds after ignition. The FAN-
OFF period is approximately 100 seconds from the interrup-
tion of gas flow.
ROOM AIR THERMOSTAT HEAT ANTICIPATOR
ADJUSTMENT
Set the thermostat heat anticipator according to the current
flow measured, or the settings found in the notes on the
furnace wiring diagram (found inside the furnace casing).
INSTRUCTIONS TO THE OWNERS
In the event that electrical, fuel, or mechanical failures
occur, the owner should immediately turn the gas
supply off at the manual gas valve, located in the burner
compartment (See Figure 26 on page 17). Also turn off
electrical power to the furnace and contact the service
agency designated by your dealer.
▲
WARNING
!
TO PREVENT AN EXPLOSION OR POSSIBLE INJURY, DEATH
AND EQUIPMENT DAMAGE, DO NOT STORE COMBUS-
TIBLE MATERIALS, GASOLINE OR OTHER FLAMMABLE
VAPORS OR LIQUIDS NEAR THE UNIT.
