System Service Checks - Lennox KGC Series Unit Information

V- SYSTEMS SERVICE CHECKS
A-Heating System Service Checks
All KGC units are ETL / CSA design certified without
modification.
Before checking piping, check with gas company or
authorities having jurisdiction for local code requirements.
Refer to the KGC Installation instruction for more
information.
1-Gas Piping
Gas supply piping must not allow more than 0.5"W.C.
(124.3 Pa) drop in pressure between the gas meter and
the unit. Supply gas pipe must not be smaller than the
unit gas connection. Refer to installation instructions for
details.
2-Testing Gas Piping
NOTE - In case emergency shutdown is required, turn off
the main manual shut-off valve and disconnect the main
power to the unit. These controls should be properly la-
beled 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. (3481 Pa)].
See FIGURE 22.
When checking piping connection for gas leaks, use the
preferred means. Common kitchen detergents can cause
harmful corrosion on various metals used in gas piping.
The use of specialty Gas Leak Detector is strongly
recommended. It is available as 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.
GAS PIPING COMPONENTS
REFER TO INSTALLATION INSTRUCTIONS
GROUND
JOINT UNION
MANUAL MAIN
SHUT-OFF VALVE
(REFER TO LOCAL CODES)
FIGURE 22
VALVE
CAP HERE
UNIT
TO ISOLATE
VALVE WHEN
PRESSURE
TESTING
LINE
ROOF
MOUNTING
FRAME
DRIP LEG
GAS PIPING
SUPPORT
3-Testing Gas Supply Pressure
When testing gas supply pressure, connect test gauge to
the inlet pressure tap located on unit gas valve GV1. Test
supply gas pressure with unit firing at maximum rate (both
stages energized). Make sure the reading falls within the
range of the following values. Low pressure may result in
erratic operation or "underfire." High pressure can result in
permanent damage to the gas valve or "overfire."
For natural gas units, operating pressure at the unit gas
connection must be a minimum of 4.7" w.c. (1.19kPa) and
a maximum of 10.5" (2.60kPa) w.c. For LP/propane gas
units, operating pressure at the unit gas connection must
be a minimum of 11" w.c. (2.74kPa) and a maximum of
13.0" w.c. (3.23kPa).
On multiple unit installations, each unit should be checked
separately while operating at maximum rate, beginning
with the one closest to the supply gas main and progressing
to the one furthest from the main. Multiple units should
also be tested with and without the other units operating.
Supply pressure must fall within the range listed in the
previous paragraph.
4-Check and Adjust Manifold Pressure
After line pressure has been checked and adjusted, check
manifold pressure. Move test gauge to the outlet pressure
tap located on unit gas valve GV1. See FIGURE 18 or
FIGURE 19 for location of pressure tap on the gas valve.
The manifold pressure is factory set and should not require
adjustment. See TABLE 4. If manifold pressure is incorrect
and no other source of improper manifold pressure can be
found, the valve must be replaced. See FIGURE 18 or
FIGURE 19 for location of gas valve (manifold pressure)
adjustment screw.
All gas valves are factory-regulated. The gas valve should
completely and immediately cycle off in the event of gas
or power failure. The manual shut-off knob can be used to
immediately shut off gas supply.
For safety, connect a shut-off valve between the
manometer and the gas tap to permit shut off of gas
pressure to the manometer.
Manifold Adjustment Procedure
1 - Connect test gauge to the outlet pressure tap on the
gas valve. Start the unit (call for second stage heat)
and allow five minutes for the unit to reach steady
state.
2 - While waiting for the unit to stabilize, notice the
flame. The flame should be stable without flashback
and should not lift from the burner heads. Natural
gas should burn basically blue with some clear
streaks. L.P. gas should burn mostly blue with some
clear yellow streaks.
3 - After allowing the unit to stabilize for five minutes,
record the manifold pressure and compare to the
values given in TABLE 4.
Page 37
CAUTION