Heating System Service Checks - Lennox EL280DF070E36A Unit Information

IV-HEATING SYSTEM SERVICE CHECKS
A-CSA Certification
All units are CSA design certified without modifications.
Refer to the EL280DFE Installation Instruction.
B-Gas Piping
IMPORTANT
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. The flexible connector can then
be added between the black iron pipe and the gas
supply line.
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.
dropin pressure b tween 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
disconnected and isolated. Gas valves can be damaged
if subjected to more than 0.5 psig (14" W.C.). See FIG-
URE 19. If the pressure is equal to or less than 0.5psig
(14"W.C.), use the manual shut-off valve before pressure
testing to isolate furnace 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
FIGURE 19
1/8 NPT PLUG
CAP
FIELD PROVIDED
LINE PRESSURE TAP
Page 23
When checking piping connections for gas leaks, use
preferred means. Kitchen detergents can cause harmful
corrosion 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
An inlet post located on the gas valve provides access to
the supply pressure. See FIGURE 18. 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 14 for supply line pressure.
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
adjustment. Manifold pressure can be measured at any
time the gas valve is open and is supplying gas to the unit.
See TABLE 14 for normal operating manifold pressure.
IMPORTANT
For safety, connect a shut-off valve between the
manometer 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:
1 - Connect test gauge to manifold pressure tap (FIGURE
18) on gas valve.
2 - Ignite unit on low fire and let run for 5 minutes to allow
for steady state conditions.
3 - After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in TA-
BLE 14.
4 - If necessary, make adjustments. FIGURE 18 shows
location of high fire and low fire adjustment screw.
5 - Repeat steps 2, 3 and 4 on high fire.
6 - Shut unit off and remove manometer as soon as an
accurate reading has been obtained. Take care to re-
place pressure tap plug.
7 - Start unit and perform leak check. Seal leaks if found.
F- Proper Gas Flow (Approximate)
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 12. If manifold pressure matches TABLE 14 and
rate is incorrect, check gas orifices for proper size and
restriction.
NOTE- To obtain accurate reading, shut off all other gas
appliances connected to meter.