Gas Heat Operation; Proper Gas Flow - Lennox LGH420 Installation Instructions Manual

TABLE 2
MANIFOLD INPUT PRESSURES
Natural Gas
Unit
1st Stage 2nd Stage
+ 0.2(+.05) + 0.3(+.08)
420-600 1.6 (0.40) 3.7 (0.92)
HONEYWELL VR8205Q/VR8305Q SERIES GAS VALVE
LOW FIRE
HIGH FIRE
ADJUSTMENT
ADJUSTMENT
MANIFOLD
INLET
PRESSURE
TAP
GAS ALVE KNOB IS SHOWN IN OFF POSITION.
FIGURE 3
WHITE RODGERS 36H54 GAS VALVE
Two-Stage
INLET
PRESSURE
TAP
GAS VALVE SWITCH SHOWN IN ON POSITION.
FIGURE 4
in.wg. (kPa)
Propane (LP) Gas
1st Stage 2nd Stage
+ 0.2(+.05) + 0.3(+.08)
5.5 (1.37) 10.5 (2.61)
MANIFOLD
OUTLET
PRESSURE
TAP
MANIFOLD
PRESSURE
TAP
HIGH FIRE
ADJUSTMENT
LOW FIRE
ADJUSTMENT
Page 4

Gas Heat Operation

See the operating instruction plate on the unit for details.
Proper Gas Flow (Approximate)
1- Operate unit at least 15 minutes before checking gas
flow. Determine the time in seconds for two
revolutions of gas through the meter. (Two
revolutions assures a more accurate time.)
2- Divide the number of seconds by two and
compare to the time in table 3. If manifold pressure is
correct and rate is incorrect, check gas orifices for
proper size and restriction.
3- Remove temporary gas meter if installed.
NOTE- To obtain accurate reading, shut off all other
gas appliances connected to meter.
TABLE 3
GAS METER CLOCKING CHART
Seconds for One Revolution
Unit In­
put Rate Natural
(Btuh)
3
2 ft Dial 3 ft
325,000 22
500,000 14
525,000 13
800,000 9
Natural-1000 btu/cu ft
Note: Table assumes standard temperature (60°F), pressure
(30in.Hg.), and fuel heating values (Btuh/ft.
corrections in altitudes above 2000 ft
LP
3 3 3
Dial 1 ft Dial 2 ft Dial
54 27 55
36 28 36
34 17 34
22 11 22
LP-2500 btu/cu ft
3
). Apply pressure