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NEGATIVE AIR
PRESSURE PORT
INLET
SUPPLY
PRESSURE
TAP
GAS VALVE SHOWN IN THE ON POSITION
Figure 57. Gas Valve
9.
Replace the access panel.
10. Turn on all electrical power to the unit.
11. Set the thermostat to desired setting.
NOTE: When unit is initially started, steps 1 through
11 may need to be repeated to purge air from gas line.
12. If the Appliance will not operate, follow the instructions
"Turning Off Gas to Unit" and call the gas supplier.
Turning Off Gas to Unit
1.
Set the thermostat to the lowest settling.
2.
Turn OFF all electrical power to the unit if service is to
be performed.
3.
Remove the access panel.
4.
Move the gas valve switch to the OFF position.
5.
Replace the 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?
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 gas valve turned on?
9.
Is the unit ignition system in lock out: If the unit locks
out again, inspect the unit for blockages.
10. Is blower harness connected to ignition control?
Furnace will not operate unless harness is connected.
508364-01
POSITIVE AIR
PRESSURE PORT
OUTLET
MANIFOLD
PRESSURE TAP
Issue 2346
Gas Pressure Measurement
Gas Flow (Approximate)
Seconds for One Revolution
Natural
Capacity
1 cu ft
Dial
-070
55
-090
41
-110
33
-135
27
Natural - 1000 btu/cu ft
Table 23. Gas Meter Clocking Chart
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
23. If manifold pressure matches Table 26 and rate is
incorrect, check gas orifices for proper size and restriction.
Remove temporary gas meter if installed.
NOTE: A natural to LP/propane gas changeover kit is
necessary to convert this unit. Refer to the changeover kit
installation instructions for the conversion procedure.
NOTE: To obtain accurate reading, shut off all other gas
appliances connected to meter.
Supply Pressure Measurement
A threaded plug on the inlet side of the gas valve provides
access to the supply pressure tap. Remove the threaded
plug, install a field provided barbed fitting and connect a
manometer to measure supply pressure. Replace the
threaded plug after measurements have been taken.
Manifold Pressure Measurement
To correctly measure manifold pressure, the differential
pressure between the positive gas manifold and the
negative burner box must be considered. Use pressure
test adapter kit (available as part 10L34) to assist in
measurement.
1.
Remove the threaded plug from the outlet side of the
gas valve and install a field provided barbed fitting.
Connect test gauge "+" connection to barbed fitting to
measure manifold pressure.
2.
Tee into the gas valve regulator vent hose and connect
test gauge "-" connection.
3.
Start unit on low heat (35% rate) and allow 5 minutes
for unit to reach steady state.
4.
While waiting for the unit to stabilize, notice the flame.
Flame should be stable and should not lift from burner.
Natural gas should burn blue.
LP
2 cu ft
1 cu ft
2 cu ft
Dial
Dial
110
136
82
102
66
82
54
68
LP - 2500 btu/cu ft
Page 51 of 74
Dial
272
204
164
136
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