508145-01
Issue 2128
Page 29 of 36
Figure 24. White Rodgers Gas Valve
GAS VALVE SHOWN IN ON POSITION
INLET PRESSURE POST
HIGH FIRE
ADJUSTMENT
(under cap)
MANIFOLD
PRESSURE TAP
LOW FIRE
ADJUSTMENT
(under cap)
Turning Off Gas to Unit
1. Set the thermostat to the lowest setting.
2. Turn OFF all electrical power to the unit if service is to
be performed.
3. Remove the upper access panel.
4. Move switch on gas valve to OFF. Do not force.
5. Replace the upper access panel.
Failure to Operate
If the unit fails to operate, check the following:
1. Is the thermostat calling for heat?
2. Are access panels securely in place?
3. Is the main disconnect switch closed?
4. Is there a blown fuse or tripped circuit breaker?
5. Is the filter dirty or plugged? Dirty or plugged filters will
cause the limit control to shut the unit off.
6. Is gas turned on at the meter?
7. Is the manual main shut-off valve open?
8. Is the internal manual shut-off valve open?
9. Is the unit ignition system in lock out? If the unit locks
out again, call the service technician to inspect the unit
for blockages.
10. Is pressure switch closed? Obstructed flue will cause
unit to shut off at pressure switch. Check flue and
outlet for blockages.
11. Are flame rollout switches tripped? If flame rollout
switches are tripped, call the service technician for
inspection.
Gas Pressure Adjustment
Gas Flow (Approximate)
Gas Meter Clocking Chart
Capacity
Seconds for One Revolution
Natural
LP
1 cu ft
Dial
2 cu ft
Dial
1 cu ft
Dial
2 cu ft
Dial
-070
55
110
136
272
-090
41
82
102
204
Natural - 1000 btu/cu ft
LP - 2500 btu/cu ft
Table 13.
Furnace should operate at least 5 minutes before checking
gas flow. Determine time in seconds for two revolutions of
gas through the meter. (Two revolutions assures a more
accurate time.) Divide by two and compare to time in Table
13. If manifold pressure matches Table 15 and rate is
incorrect, check gas orifices for proper size and restriction.
Remove temporary gas meter if installed.
NOTE:
To obtain accurate reading, shut off all other gas
appliances connected to meter.
Supply Pressure Measurement
An inlet post located on the gas valve provides access to
the supply pressure. See Figure 24. Back out the 3/32”
hex screw one turn, connect a piece of 5/16” tubing and
connect to a manometer to measure supply pressure. See
Table 15 for supply line pressure.
Manifold Pressure Measurement
A manifold pressure tap located on the gas valve provides
access to the manifold pressure. See Figure 24. Back out
the 3/32” hex screw one turn, connect a piece of 5/16”
tubing and connect to a manometer to measure manifold
pressure.
NOTE:
Pressure test adapter kit (10L34) is available from
Allied Air to facilitate manifold pressure measurement.
1.
Connect test gauge to manifold pressure tap (Figure
2. Ignite unit on low fire and let run for 5 minutes to allow
for steady state conditions.
3. After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in
4. If necessary, make adjustments. Figure 24 shows
location of high fire and low fire adjustment screw.
5. Repeat steps 2, 3 and 4 on high fire.
