508142-01
Issue 2047
Page 22 of 33
Figure 17. Gas Piping Test Procedure
MANUAL MAIN SHUT-OFF VALVE
WILL NOT HOLD TEST PRESSURE
IN EXCESS OF 0.5 PSIG (14”W.C.)
GAS VALVE
CAP
FIELD PROVIDED
LINE PRESSURE TAP
When checking piping connections for gas leaks, use
preferred means. Kitchen detergents can cause harmful
corrosion on various metals used in gas piping. Use of a
specialty Gas Leak Detector is strongly recommended.
Do not use matches, candles, flame or any other source
of ignition to check for gas leaks.
WARNING
Gas Pressure Adjustment
Gas Flow (Approximate)
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 8. If manifold pressure matches Table 10 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.
Capacity
Seconds for One Revolution
Natural
LP
1 cu ft
Dial
2 cu ft
Dial
1 cu ft
Dial
2 cu ft
Dial
-45
80
160
200
400
-70
55
110
136
272
-90
41
82
102
204
-110
33
66
82
164
Natural-1000 btu/cu ft LP-2500 btu/cu ft
Table 8. Gas Meter Clocking Chart
Supply and Manifold Pressure
Supply Pressure Measurement
1.
Remove the threaded plug from the inlet side of the
gas valve and install a field-provided barbed fitting.
Connect to a test gauge to measure supply pressure.
2.
Start unit and allow 5 minutes for unit to reach steady
state.
3.
After allowing unit to stabilize for 5 minutes, record
supply pressure and compare to value given in Table
Manifold Pressure Measurement
1.
Remove the threaded plug from the outlet side of the
gas valve and install a field-provided barbed fitting.
Connect to a test gauge to measure manifold pressure.
2.
Start unit and allow 5 minutes for unit to reach steady
state.
3.
While waiting for the unit to stabilize, observe the
flame. Flame should be stable and should not lift from
burner. Natural gas should burn blue.
4.
After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in
NOTE:
Shut unit off and remove manometer as soon as an
accurate reading has been obtained. Take care to remove
barbed fitting and replace threaded plug.
Proper Combustion
Furnace should operate a minimum 15 minutes with correct
manifold pressure and gas flow rate before checking
combustion. Take combustion sample beyond the flue
out let and compare to Table 9. The maximum carbon
monoxide reading should not exceed 100 ppm.
Capacity
CO²% For Nat
CO²% For LP
-045
7.2 - 7.8
7.5 - 9.0
-070
-090
-110
Table 9.
High Altitude
The manifold pressure may require adjustment and
combustion air pressure switch may need replacing to
ensure proper combustion at higher altitudes. Refer
to Table 10 for manifold pressure and pressure switch
change.
For safety, shut unit off and remove manometer as soon
as an accurate reading has been obtained. Take care to
replace pressure tap plug.
IMPORTANT
