Lennox iComfort SL280UH070V36A Manual page 44

D-Extended Period Shutdown
Turn off thermostat or set to "UNOCCUPIED" mode. Close
all gas valves (both internal and external to unit) to guaran­
tee no gas leak into combustion chamber. Turn off power to
unit. All access panels and covers must be in place and se­
cured.
IV-HEATING SYSTEM SERVICE CHECKS
A-CSA Certification
All units are CSA design certified without modifications.
Refer to the SL280UHV(X) Installation Instruction.
B-Gas Piping
CAUTION
If a flexible gas connector is required or allowed by
the authority that has jurisdiction, black iron pipe
shall be installed at the gas valve and extend outside
the furnace cabinet.
WARNING
Do not over torque (800 in-lbs) or under torque (350
in-lbs) when attaching the gas piping to the gas
valve.
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 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 dis­
connected and isolated. Gas valves can be damaged if
subjected to more than 0.5 psig (14" W.C.). See figure 19. If
the pressure is greater than 0.5psig (14"W.C.), use the
manual shut-off valve before pressure testing to isolate fur­
nace from gas supply.
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
When checking piping connections for gas leaks, use pre­
ferred means. Kitchen detergents can cause harmful corro­
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
White Rodgers Gas Valve
An inlet post located on the gas valve provides access to
the supply pressure. See figure 17. Back out the 3/32 hex
screw one turn, connect a piece of 5/16 tubing and connect
to a manometer to measure supply pressure. See table 19
for supply line pressure.
Honeywell Gas Valve
A threaded plug on the inlet side of the gas valve provides
access to the supply pressure tap. Remove the threaded
plug, install a field-provided barbed fitting and connect a
manometer to measure supply pressure. See table 19 for
supply line pressure. Replace the threaded plug after mea­
surements have been taken.
E-Check Manifold Pressure
After line pressure has been checked and adjusted, check
manifold pressure. Move pressure gauge to outlet pres­
sure tap located on unit gas valve (GV1). Checks of man­
ifold pressure are made as verification of proper regulator ad­
justment. Manifold pressure for the SL280UHV(X) can be
measured at any time the gas valve is open and is supplying
gas to the unit. See table 19 for operating manifold pressure.
IMPORTANT
For safety, connect a shut‐off valve between the ma­
nometer and the gas tap to permit shut off of gas
pressure to the manometer.
The gas valve is factory set and should not require adjust­
ment. All gas valves are factory regulated.
Manifold Adjustment Procedure:
NOTE - Pressure test adapter kit (10L34) is available from
Lennox to facilitate manifold pressure measurement.
1 - Connect test gauge to manifold pressure post (figure
17) or tap (figure 18) on gas valve.
Page 44
1/8 NPT PLUG
CAP
FIGURE 19