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WARNING
Shock and burn hazard.
G17 units are equipped with an intermittent pilot
ignition system. Do not attempt to light manually.
4- Set fan switch to AUTO or ON and move system
selection switch to HEAT. Adjust thermostat to a setĆ
ting 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 unit power. Close manual and 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 guaranĆ
tee 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 modifications.
Refer to the G17 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 connection.
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 shutĆoff 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 damaged if
subjected to more than 0.5psig (14" W.C.). See figure 13
.
If
the pressure is equal to or less than 0.5psig (14"W.C.), use
the manual shut-off valve before pressure testing to isoĆ
late furnace from gas supply.
FIGURE 13
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 preĆ
ferred means. Kitchen detergents can cause harmful corroĆ
sion on various metals used in gas piping. Use of a specialty
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-Testing Gas Supply Pressure
When testing supply gas pressure, connect test gauge to
inlet pressure tap (field provided). See figure 13. Check
gas line pressure with unit firing at maximum rate. Low
pressure may result in erratic operation or underfire. High
pressure can result in permanent 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 connecĆ
tion 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 presĆ
sure must fall within range listed in previous paragraph.
E-Check Manifold Pressure
After line pressure has been checked and adjusted, check
manifold pressure. Checks of manifold pressure are made
as verification of proper regulator adjustment. Manifold presĆ
sure for the G17 can be measured at any time the gas valve
is open and is supplying gas to the unit. Normal manifold
pressure for natural gas units is 3.5 in. w.c. For LP/propane
gas the correct manifold pressure is 9.5 in. w.c. See tables 5
and 6 for derated manifold pressure values in high altitude
application for both natural and LP gases. Move pressure
gauge to outlet pressure tap located on unit gas valve
(GV1). See figure 8 for location of pressure tap on gas
valve.
