SERVICING
53
f. Remove regulator cover screw from the outlet pres-
sure regulator adjust tower and turn screw clock-
wise to increase pressure or counterclockwise to
decrease pressure. Replace regulator cover screw.
i. Turn off all electrical power and gas supply to the
system.
j. Remove the manometer hose from the hose barb
fitting or outlet pressure boss.
k. Remove the 1/8" NPT hose barb fitting from the out-
let pressure tap. Replace the outlet pressure boss
plug and seal with a high quality thread sealer.
WARNING
HIGH
VOLTAGE
D
ISCONNECT
ALL
ELECTRICAL POWER AND SHUT OFF GAS
SUPPLY BEFORE SERVICING OR INSTALLING THIS UNIT.
M
ULTIPLE POWER SOURCES MAY BE PRESENT.
F
AILURE TO
DO SO MAY CAUSE PROPERTY DAMAGE, PERSONAL INJURY OR DEATH.
7. Turn on gas to furnace and check for leaks. If leaks are
found, repair and then reinstall burner compartment
door.
8. Turn on electrical power and verify proper unit opera-
tion.
Pressure Regulator
Adjustment
(Under Cap Screw)
Gas Valve
On/Off
Selector
Switch
INLET
OUTLET
Inlet Pressure
Tap
Outlet Pressure
Tap
White-Rodgers Model 36J22 (Single-Stage)
Gas Valve On/Off
Selector Switch
Inlet
Pressure
Tap
Pressure Regulator
(under cap screw)
Outlet
Pressure
Tap
Honeywell Model VR8215
Gas
Rate
Range
Nominal
High Stage 9.7 to 10.3" w.c. 10.0" w.c.
Low Stage 5.7 to 6.3" w.c. 6.0" w.c.
Manifold Gas Pressure
Propane Gas
S-308 CHECKING HOT SURFACE IGNITOR
Single stage furnaces use a 115 volt silicon carbide igniter
(p/n 0130F00008) with 17-second warm up time.
D
ISCONNECT
ALL
POWER BEFORE SERVICING.
WARNING
1. Remove burner compartment door to gain access to the
ignitor.
2. Ignitor cool - approximately 70 - 77°F.
3. Disconnect the ignitor from the Ignition Control.
4. Using an ohmmeter measure the resistance of the igni-
tor: -at room temperature a normal reading will be 37 -
68 ohms.
5. Reconnect ignitor.
L
INE VOLTAGE NOW PRESENT
WARNING
6. Place unit in heating cycle, measure current draw of ig-
nitor during preheat cycle.
S-309 CHECKING FOR FLASHBACK
Flashback will also cause burning in the burner venturi, but
is caused by the burning speed being greater than the gas-
air flow velocity coming from a burner port.
Flashback may occur at the moment of ignition, after a burner
heats up or when the burner turns off. The latter is known as
extinction pop.
Since the end results of flashback and delayed ignition can
be the same (burning in the burner venturi) a definite attempt
should be made to determine which has occurred.
If flashback should occur, check for the following:
1. Improper gas pressure - adjust to proper pressure (See
S-307 CHECKING GAS PRESSURE
)..
2. Check burner for proper alignment and/or replace burner.
3. Improper orifice size - check orifice for obstruction.
S-310 CHECKING PRESSURE SWITCH
The pressure control is a safety device to prevent the com-
bustion cycle from occurring with inadequate venting caused
by a restricted or blocked vent pipe.
