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B – Heating Start-Up
WARNING
Shock and burn hazard.
G20RE and G20RXE units are equipped with an in-
termittent pilot ignition system. Do not attempt
to light manually.
1 – Set thermostat to OFF position. Close manual knob
on gas valve.
2 – Wait 5 minutes.
3 – Open manual knob on gas valve, replace burner ac-
cess door and turn on unit electrical supply.
4 – Set fan switch to AUTO or ON and move system
selection switch to HEAT. Adjust thermostat to a
setting above room temperature.
5 – If unit does not light the first time, it will attempt
one more ignition before locking out.
6 – If lockout occurs, repeat steps 1, 2, 3 and 4.
C – Safety or Emergency Shutdown
Turn off power to unit. Close manual and/or main gas
valves.
D – Extended Period Shutdown
Turn off thermostat or set to “UNOCCUPIED” mode.
Close all gas valves (both internal and external to unit)
to guarantee no gas leak into combustion chamber.
Turn off power to unit. All access panels, covers and
vent caps must be in place and secured.
V – HEATING SYSTEM SERVICE CHECKS
A – A.G.A. Applications and Requirements
All units are A.G.A. design certified without modifica-
tions. Refer to the G20RE Operation and Installation
Instruction Manual Information.
B – Gas Piping
Gas supply piping should not allow more than
0.5”W.C. drop in pressure between gas meter and unit.
Supply gas pipe must not be smaller than unit gas con-
nection.
Compounds used on gas piping threaded joints should
be resistant to action of liquefied petroleum gases.
C – Testing Gas Piping
IMPORTANT
In case emergency shutdown is required, turn off
the main shut-off valve and disconnect the main
power to unit. These controls should be properly
labeled by the installer.
When pressure testing gas lines, the gas valve must be
disconnected and isolated. Gas valves can be dam-
aged if subjected to more than 0.5psig (14” W.C.). See
figure 11
. If the pressure is equal to or less than 0.5psig
(14”W.C.), use the manual shut–off valve before pres-
sure testing to isolate furnace from gas supply.
FIGURE 11
MANUAL MAIN SHUT–OFF VALVE
WILL NOT HOLD TEST PRESSURE
IN EXCESS OF 0.5 PSIG (14”W.C.)
GAS VALVE
CAP
GAS PIPING TEST PROCEDURE
FIELD PROVIDED
LINE PRESSURE TAP
When checking piping connections for gas leaks, use
preferred means. Kitchen detergents can cause harm-
ful corrosion on various metals used in gas piping. Use
of a specialty Gas Leak Detector is strongly recom-
mended. It is available through Lennox under part
number 31B2001. See Corp. 8411–L10, for further de-
tails.
Do not use matches, candles, flame or any other source
of ignition to check for gas leaks.
D – Testing Gas Supply Pressure
When testing supply gas pressure, connect test gauge
to inlet pressure tap (field provided). See figure 11. Test
supply gas pressure. Low pressure may result in erratic
operation or underfire. High pressure can result in per-
manent damage to gas valve or overfire. For natural
gas units, operating pressure at unit gas connection
must be between 4.5” W.C. and 10.5” W.C. For L.P. gas
units, operating pressure at unit gas connection must
be between 10.5” W.C. and 13.5” W.C.
On multiple unit installations, each unit should be
checked separately, with and without units operating.
Supply pressure must fall within range listed in pre-
vious paragraph.
