GC9C80 Service Manual

SERVICING
33
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
T  RT RB RT R T G T
T G  RR T B    T T
RTG T T  TR  G R 
RTG

1. Turn OFF gas to furnace at the manual gas shuto󰀨
valve external to the furnace.
2. Turn o󰀨 all electrical power to the system.
3. Outlet pressure tap connections:
White-Rodgers 36J54 valve: Back outlet pressure test
screw (inlet/outlet pressure tap) out one turn (counter-
clockwise, not more than one turn).
4. Attach a hose and manometer to the outlet pressure
tap (White-Rodgers valve).
5. Turn ON the gas supply.
6. Turn on power and close thermostat “R” and “W1” con-
tacts to provide a call for low stage heat.
7. Measure the gas manifold pressure with burners ring.
Adjust manifold pressure using the Manifold Gas Pres-
sure table shown below.
8. Remove regulator cover screw from the low (LO) outlet
pressure regulator adjust tower and turn screw clock-
wise to increase pressure or counterclockwise to de-
crease pressure. Replace regulator cover screw.
9. Close thermostat “R”, “W1” and “W2” contacts to pro-
vide a call for high stage heat.
10. Remove regulator cover screw from the high (HI) outlet
pressure regulator adjust tower and turn screw clock-
wise to increase pressure or counterclockwise to de-
crease pressure. Replace regulator cover screw.
11. Turn o󰀨 all electrical power and gas supply to the sys-
tem.
12. Remove the manometer hose from the hose barb tting
or outlet pressure tap.
13. Replace outlet pressure tap:
White-Rodgers 36J54 valve: Turn outlet pressure test
screw in to seal pressure port (clockwise, 7 in-lb mini-
mum).
14. Turn on electrical power and gas supply to the system.
15. Close thermostat contacts “R” and “W1/W2” to ener-
gize the valve.
 
Natural Low Stage 1.6 - 2.2" w .c. 1.9" w .c.
High Stage 3.2 - 3.8" w .c. 3.5" w .c.
Propane Low Stage 5.7 - 6.3" w .c. 6.0" w .c.
High Stage
9.7 - 10.3" w .c.
10.0" w .c.


Using a leak detection solution or soap suds, check for leaks at
screw (White-Rodgers valve). Bubbles forming indicate a leak.
SHUT OFF GAS AND REPAIR ALL LEAKS IMMEDIATELY!
For gas to gas conversion, consult your dealer for
appropriate conversion.
T
 RT RB RT R T G T
T G  RR T B    T T
RTG T T  TR  G R 
RTG

1. Remove regulator cover screw from the low (LO) outlet
pressure regulator adjust tower and turn screw clockwise
to increase pressure or counterclockwise to decrease
pressure. Replace regulator cover screw.
a. Close thermostat “R” and “W” contacts to provide a call
for heat.
b. Remove regulator cover screw from the high (HI)
outlet pressure regulator adjust tower and turn screw
clockwise to increase pressure or counterclockwise to
decrease pressure. Replace regulator cover screw.
c. Turn o󰀨 all electrical power and gas supply to the
system.
d. Remove the manometer hose from the outlet pressure
boss.
e. Remove the 1/8” NPT hose barb tting from the outlet
pressure tap. Replace the outlet pressure boss plug
and seal with a high quality thread sealer.

G TG

T  TR R  T  G 
BR RG R TG