GMES8 GCES8 Installation Instructions
25
counterclockwise to decrease pressure. Replace regulator
cover screw.
10. Turn OFF all electrical power and gas supply to the system.
11. Remove the manometer hose from the hose barb fitting
or outlet pressure Tap.
12. Replace outlet pressure tap:
a. Honeywell valve:
Remove the 1/8” NPT hose barb fitting from the outlet
pressure tap. Replace the outlet pressure boss plug and
seal with a high quality thread sealer.
b. White-Rodgers valve: Turn outlet pressure test screw in
to seal pressure port (clockwise, 7 in-lb minimum).
13. Turn ON electrical power and gas supply to the system.
14. Close thermostat contacts to provide a call for heat.
15. Retest for leaks. If bubbles form, SHUT OFF GAS AND
REPAIR ALL LEAKS IM M EDIATELY!
to increase pressure or counterclockwise to decrease pressure.
Replace regulator cover screw.
11. Turn off all electrical power and gas supply to the system.
12. Remove the manometer hose from the hose barb fitting
or outlet pressure Tap.
13. Replace outlet pressure tap:
a. Honeywell valve: Remove the 1/8" NPT hose barb fitting
from the outlet pressure tap. Replace the outlet pressure
Tap plug and seal with a high quality thread sealer.
b. White-Rodgers valve: Turn outlet pressure test screw
in to seal pressure port (clockwise, 7 in-lb minimum).
14. Turn on electrical power and gas supply to the system.
15. Close thermostat contacts “R” and “W1/ W2” to energize
the valve.
Range Nominal
Natural High Stage 3.2 - 3.8" w.c. 3.5" w.c.
Propane High Stage 9.7 - 10.3" w.c. 10.0" w.c.
Ma ni fold Ga s P r e ssu re
Gas
GAS INPUT RATE M EASUREM ENT (NATURAL GAS ONLY)
The gas input rate to the furnace must never be greater than that
specified on the unit rating plate. To measure natural gas input
using the gas meter, use the following procedure.
1. Turn OFF the gas supply to all other gas-burning appliances
except the furnace.
2. While the furnace is operating, time and record one
complete revolution of the smallest gas meter dial.
3. Calculate the number of seconds per cubic foot (sec/ ft
3
) of
gas being delivered to the furnace. If the dial is a two cubic
foot dial, divide the number of seconds recorded in step 2
by two.
4. Calculate the furnace input in BTUs per hour (BTU/ hr).
Input equals the installation’s gas heating value multiplied
by a conversion factor (hours to seconds), divided by the
number of seconds per cubic foot. The measured input
must not be greater than the input indicated on the unit
rating plate.
EXAM PLE:
Installation’s gas heating (HTG) value: 1,000 BTU/ ft
3
(Obtained from gas supplier)
13. Turn ON electrical power and gas supply to the system.
14. Turn valve switch ON.
GAS M ANIFOLD PRESSURE M EASUREM ENT AND ADJUSTM ENT
T
O
PREVENT
UNRELIABLE
OPERATION
OR
EQUIPM ENT
DAM AGE
,
THE
GAS
M ANIFOLD
PRESSURE
M UST
BE
AS
SPECIFIED
ON
THE
UNIT
RATING
PLATE
. O
NLY
M INOR
ADJUSTM ENTS
SHOULD
BE
M ADE
BY
ADJUSTING
THE
GAS
VALVE
PRESSURE
REGULATOR
.
CAUTION
HIGH VOLTAGE !
D
ISCONNECT
ALL
POW ER
BEFORE
SERVICING
OR
INSTALLING
THIS
UNIT
. M
ULTIPLE
POW ER
SOURCES
M AY
BE
PRESENT
. F
AILURE
TO
DO
SO
M AY
CAUSE
PROPERTY
DAM AGE
,
PERSONAL
INJURY
OR
DEATH
.
WARNING
MODELS USING SINGLE STAGE GAS VALVES
This valve is shipped from the factory with the regulator preset
(see control label).
Consult the appliance rating plate to ensure burner manifold pres-
sure is as specified. If another outlet pressure is required, follow
these steps.
1. Turn OFF gas to furnace at the manual gas shutoff valve
external to the furnace.
2. Turn OFF all electrical power to the system.
3. Outlet pressure tap connections:
a. Honeywell valve:
Remove the outlet pressure Tap plug. Install an 1/8” NPT
hose barb fitting into the outlet pressure tap.
b. White-Rodgers valve:
Back outlet pressure test screw (outlet pressure Tap) out
one turn (counterclockwise, not more than one turn).
4. Attach a hose and manometer to the outlet pressure barb
fitting (Honeywell valve) or outlet pressure Tap (White-
Rodgers valve).
5. Turn ON the gas supply.
6. Turn ON power and close thermostat “R” and “ W” contacts
to provide a call for heat.
7. Using a leak detection solution or soap suds, check for
leaks at outlet pressure Tap plug (Honeywell valve) or screw
(White-Rodgers valve). Bubbles forming indicate a leak.
SHUT OFF GAS AND REPAIR ALL LEAKS IM M EDIATELY!
8. Measure the gas manifold pressure with burners firing.
Adjust manifold pressure using the following Manifold Gas
Pressure table.
Natural Gas 3.2" - 3.8" w.c.
Propane Gas 9.7" - 10.3" w.c.
M anifold Gas Pressure
9. Remove regulator cover screw from the outlet pressure
regulator and turn screw clockwise to increase pressure or