Heating System Service Checks - Lennox EL296UHE Series Unit Information

IV-HEATING SYSTEM SERVICE CHECKS
A-CSA Certification
All units are CSA design certified without modifications.
Refer to the EL296UHE 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. 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.
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
disconnected and isolated. Gas valves can be damaged if
subjected to more than 0.5 psig (14" W.C.). See figure 51.
If the pressure is greater than 0.5psig (14"W.C.), use the
manual shut-off valve before pressure testing to isolate
furnace from gas supply.
MANUAL MAIN SHUT-OFF
VALVE WILL NOT HOLD
NORMAL TEST PRESSURE
1/8" N.P.T. PLUGGED TAP
FIGURE 51
CAP
FURNACE
ISOLATE
GAS VALVE
Page 45
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 50. 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 23 for supply line pressure.
E-Check Manifold Pressure
A manifold pressure post located on the gas valve pro-
vides access to the manifold pressure. See figure 50.
Back out the 3/32 hex screw one turn. Follow the steps
below and use figure 52 as a reference. Gas manifold Kit
10L34 provides additional components if needed
1 - Connect the 5/16" round tubing to the manifold post.
Secure with the clamp.
2 - Connect the reducer fitting to the 5/16" round tubing
followed by a piece of 10" length square tubing.
3 - Connect the other end of the square tubing to the
"+" positive side of the measuring device.
4 - Take the 2" length square tubing, tee, 10" length of
square tubing and tee into the gas valve regulator
vent hose. Connect to the measuring device
negative "-" side.
5 - Ignite unit on low fire and let run for 5 minutes to
allow for steady state conditions.
6 - After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in
table 23 or 24.
7 - If necessary, make adjustments. Figure 50 shows
location of high fire and low fire adjustment screws.
8 - Repeat steps 5, 6 and 7 on high fire. See values in
table 23 or 24.
9 - Shut unit off and remove manometer as soon as an
accurate reading has been obtained.
10 - Start unit and perform leak check. Seal leaks if
found.
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.