Lennox KGC Series Unit Information page 38

5-High Altitude
See table of contents for "High Altitude Derate" section for
altitudes above 2000 feet (610 m).
6-Proper Gas Flow
Furnace should operate at least 5 minutes before checking
gas flow. Determine time in seconds for two revolutions of
gas through the meter. (Two revolutions assures a more
accurate time.) Divide by two and compare to time in table
19. Seconds in TABLE 19 are based on a 1 cu.ft. dial
and gas value of 1000 btu's for natural and 2500 btu's for
LP. Adjust manifold pressure on gas valve to match time
needed.
NOTE - To obtain accurate reading, shut off all other gas
appliances connected to meter.
TABLE 19
Unit (BTU) Seconds for
84,500
117,000
130,000
156,00
180,000
240,000
7-Heat Exchanger
To Access or Remove Heat Exchanger From Unit:
1 - Turn off gas and electric power.
2 - .Remove access panel(s) and unit center mullion.
3 - Remove gas valve, manifold assembly and burners.
4 - Remove combustion air inducer and flue box cover.
Pay careful attention to the order in which gaskets
and orifice are removed.
5 - Support heat exchanger (to prevent it from falling
when final screws are removed.)
6 - Remove screws supporting heat exchanger.
7 - To install heat exchanger, reverse procedure. Be
sure to secure all wires and check plumbing and
burner plate for airtight seal. Screws must be
torqued to 35 in.-lbs. to ensure proper operation.
Seconds for
Natural Propane
43 106
31 77
28 69
23 58
20 50
15 37
8-Flame Sensing
Flame current is an electrical current which passes from
the ignition control through the sensor electrode during
unit operation. The current passes from the sensor through
the flame to the ground electrode (located on the flame
electrode) to complete a safety circuit. The electrodes
should be located so the tips are at least 1/2" (12.7 mm)
inside the flame envelope. Do not bend electrodes. To
measure flame current, follow the procedure on the
following page:
Electrodes are not field adjustable. Any alterations
to the electrode may create a hazardous condition
that can cause property damage or personal injury.
1 - Disconnect power to unit.
2 - Remove lead from sensing electrode and install
a 0-50DC microamp meter in series between the
sensing electrode and the sensing lead.
3 - Reconnect power and adjust thermostat for heating
demand.
4 - When flame is established, microamp reading
should be 0.5 to 1.0. Do not bend electrodes.
Dropout signal is .09 or less.
5 - Disconnect power to unit before disconnecting
meter. Make sure sensor wire is securely
reconnected before reconnecting power to unit.
NOTE-If the meter scale reads 0, the leads are
reversed. Disconnect power and reconnect leads for
proper polarity.
B-Cooling System Service Checks
KGC units are factory charged and require no further
adjustment; however,
periodically using the approach method. The approach
method compares actual liquid temperature with the
outdoor ambient temperature. See section IV- CHARGING.
NOTE - When unit is properly charged, discharge line
pressures should approximate those in TABLE 10 through
TABLE 17.
Page 38
CAUTION
charge should be checked