Gas Pressure Measurement; Proper Combustion; High Altitude - Lennox ELITE Series Installation Instructions Manual

Gas Pressure Adjustment
Gas Flow (Approximate)
GAS METER CLOCKING CHART
EL195
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 check-
ing gas flow. Determine time in seconds for two revolu-
tions of gas through the meter. (Two revolutions assures a
more accurate time.) Divide by two and compare to time
in table 9 below. 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.
Supply Pressure Measurement
When testing supply gas pressure, use the 1/8" N.P.T.
plugged tap or pressure post located on the gas valve to
facilitate test gauge connection. See figure 59. Check gas
line pressure with unit firing at maximum rate. Low pres-
sure may result in erratic operation or underfire. High pres-
sure can result in permanent damage to gas valve or over-
fire.
On multiple unit installations, each unit should be checked
separately, with and without units operating. Supply pres-
sure must fall within range listed in table 10.
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 manometer to measure manifold pres-
sure.
2 − Start unit and allow 5 minutes for unit to reach steady
state.
Downloaded from ManualsNet.com
TABLE 9
Seconds for One Revolution
Natural LP
2 cu ft 1 cu ft
Dial Dial
160 200
110 136
82 102
66 82
54 68
LP−2500 btu/cu ft
search engine
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
10.
NOTE − Shut unit off and remove manometer as soon as an
2 cu ft accurate reading has been obtained. Take care to remove
DIAL
barbed fitting and replace threaded plug.
400
272
Supply Line and Manifold Pressure (inches w.c.)
204
164
Unit
136
All
All

Proper Combustion

Furnace should operate minimum 15 minutes with correct
manifold pressure and gas flow rate before checking com-
bustion. Take combustion sample beyond the flue outlet
and compare to the tables below.
EL195
Unit
−045
−070
−090
−110
−135
The maximum carbon monoxide reading should not exceed 50 ppm.
High Altitude Information
NOTE − In Canada, certification for installations at eleva-
tions over 4500 feet (1372 m) is the jurisdiction of local au-
thorities.
Units installed at altitude of 4501 − 10,000 feet (1373 to
3048m) may require a pressure switch change which can
be ordered separately. Table 12 lists conversion kit and
pressure switch requirements at varying altitudes.
The combustion air pressure switch is factory−set and re-
quires no adjustment.
Page 42
TABLE 10
Manifold
Fuel
Pressure
Nat 3.5
LP/Propane 10.0
TABLE 11
CO %
2 For Nat
7.2 − 8.2
Line Pressure
4.5 − 10.5
11.0 − 13.0
CO %
2 For LP
8.6 − 9.6