21
6. Turn ON power and close thermostat “R” and “W” con-
tacts to provide a call for heat.
7.
Using a leak detection solution or soap suds to check
for leaks at outlet pressure tap. Bubbles forming
indicate a leak. SHUT OFF GAS AND REPAIR ALL
LEAKS IMMEDIATELY!
8.
Measure the gas manifold pressure with burners firing.
Adjust manifold pressure using the
Manifold Gas Pres
-
sure
table shown below.
Natural Gas
3.2" - 3.8" w.c.
Propane Gas
9.7" - 10.3" w.c.
Manifold Gas Pressure
9. Remove regulator cover screw from the outlet pres-
sure regulator and turn screw clockwise to increase
pressure or 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:
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 IMMEDIATELY!
Gas Input Rate Measurement (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 appli-
ances 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.
EXAMPLE:
Installation’s gas heating (HTG) value: 1,000 BTU/ft
3
(Obtained from gas supplier)
Installation’s seconds per cubic foot: 34 sec/ ft
3
Conversion Factor (hours to seconds): 3600 sec/hr
Input = (Htg. value x 3600) ק seconds per cubic foot
Input = (1,000 BTU/ft
3
x 3600 sec/hr) ק 34 sec/ ft
3
Input = 106,000 BTU/hr
Natural Gas
Minimum: 4.5" w.c.
Maximum: 10.0" w.c.
Propane Gas Minimum: 11.0" w.c. Maximum: 13.0" w.c.
INLET GAS SUPPLY PRESSURE
.
Measuring Inlet Gas Pressure (Alt. Method)
Gas Manifold Pressure Measurement and
Adjustment
CAUTION
To prevent unreliable operation or equipment damage, the
gas manifold pressure must be as specified on the unit rating
plate. Only minor adjustments should be made by adjusting
the gas valve pressure regulator.
WARNING
HIGH VOLTAGE!
Disconnect all power before servicing or
installing this unit. Multiple power sources
may be present. Failure to do so may cause
property damage, personal injury or death.
This valve is shipped from the factory with the regulator pre-
set (see control label).
Consult the appliance rating plate to ensure burner mani-
fold pressure is as specified. If another outlet pressure is re
-
quired, 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:
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
tap.
5. Turn ON the gas supply.
