Lennox EL180UHE Series Manual page 21

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
FIGURE 20
When checking piping connections for gas leaks, use pre­
ferred means. Kitchen detergents can cause harmful cor­
rosion on various metals used in gas piping. Use of a spe­
cialty Gas Leak Detector is strongly recommended. It is
available through Lennox under part number 31B2001.
See Corp. 8411-L10, for further details.
Do not use matches, candles, flame or any other source of
ignition to check for gas leaks.
D- Gas Pressure Adjustment
Gas Flow (Approximate)
TABLE 9
GAS METER CLOCKING CHART
Seconds for One Revolution
Natural
EL180UHE
Unit 1 cu ft
Dial
-045 80
-070 55
-090 41
-110 33
-135 27
Natural-1000 btu/cu ft
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
9. If manifold pressure matches table 11 and rate is incor­
rect, check gas orifices for proper size and restriction. Re­
move temporary gas meter if installed.
NOTE - To obtain accurate reading, shut off all other gas
appliances connected to meter.
E- 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.
CAP
FIELD PROVIDED
LINE PRESSURE TAP
LP
2 cu ft 1 cu ft 2 cu ft
Dial Dial DIAL
160 200 400
110 136 272
82 102 204
66 82 164
54 68 136
LP-2500 btu/cu ft
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
11.
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 pres­
sure.
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 table
11.
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.
F- Proper Combustion
Furnace should operate a minimum 15 minutes with cor­
rect manifold pressure and gas flow rate before checking
combustion. Take combustion sample beyond the flue out­
let and compare to the tables below. The maximum carbon
monoxide reading should not exceed 50 ppm.
EL180UHE Unit
045
070
090
110
135
The maximum carbon monoxide reading is 50 ppm.
G- High Altitude
The manifold pressure may require adjustment and com­
bustion air pressure switch may need replacing to ensure
proper combustion at higher altitudes. Refer to table 11 for
manifold pressure and table 12 for pressure switch change
and gas conversion kits.
For safety, shut unit off and remove manometer as
soon as an accurate reading has been obtained.
Take care to replace pressure tap plug.
Page 21
TABLE 10
CO %
2 For Nat
7.2 - 7.8
IMPORTANT
CO %
2 For LP
7.5 - 9.0