Service - Lennox G21Q Series Installation Instructions Manual

5-481+-
WARNING
Disconnect power before servicing unit.
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At the beginning of each heating season, system
should be checked as follows:
1 - - Check all wiring for loose connections.
2 - - Check fuse located on unit control box. Fuse
should be a 2 amp AGC fast blow.
3 - - Check for correct voltage at unit (unit operating).
4 - - Check amp- -draw on blower motor.
Motor Nameplate_________Actual_________
5 - - Check to see that heat (if applicable) is operating.
1 - - Check and clean blower wheel.
2 - - Motors are pre- -lubricated for extended life; no fur-
ther lubrication is required.
1 - - Filters must be cleaned or replaced when dirty to
assure proper furnace operation.
2 - - Reusable foam filters supplied with G21 can be
washed with water and mild detergent. When dry,
they should be sprayed with filter handicoater prior
to reinstallation. Filter handicoater is RP Products
coating no. 481 and is available as Lennox part no.
P- -8- -5069.
3 - - If replacement is necessary, order Lennox part
number :P- -8- -7822 for 16 X 25 inch (406 x 635mm)
filter used on all - -40, - -60, and Q3 and Q4- -80 units;
and P- -9- -7831 for 20 X 25 inch (508 x 635mm) filter
used on Q5- -80, and all - -100 units.
Air Diaphragm
1 - - Check for signs of wear, holes or fraying.
2 - - Material must be changed every four years.
Intake and Exhaust Lines
Check intake and exhaust PVC lines and all connections
for tightness and make sure there is no blockage. Also
check and clean condensate system for free flow dur-
ing operation.
Insulation
Outdoor piping insulation should be inspected yearly for
deterioration. If necessary, replace with same materials.
Electrical
Blower
Filters
Cleaning Heat Exchanger/Burner Assembly
Cleaning the heat exchanger is not a required annual
maintenance. If cleaning is required, follow the below
procedure.
NOTE- -Use papers or protective covering in front of fur-
nace while removing heat exchanger assembly. Refer
to figure 1 when disassembling unit.
Before removing spark plug and sensor wires after
unit has been operating, unit should be allowed to
cool down at least 15 minutes before placing hands
into heat chamber access opening. Residual heat in
combustion chamber transfers back to air intake
valve causing it to become very hot when unit is
first shut down.
perature, blower should be run continuously for ap-
proximately 40 minutes.
1 - - Turn off the electrical and gas supply to the furnace.
2 - - Remove the upper and lower furnace access panels.
3 - - Remove the cover from the air decoupler box.
4 - - Remove insulation pieces from the lower section
of the air decoupler box.
5 - - Unscrew the air valve housing along with the
bushing.
6 - - Disconnect the wiring to the purge blower.
7 - - Remove the nut from the PVC air inlet fitting.
8 - - Remove nuts from the air decoupler box mounting
bolts and the gas decoupler bracket.
9 - - Remove the air decoupler box from the unit.
10- - Remove the rubber pad(s) from the air pipe.
11- - Detach the PVC exhaust pipe from the coil manifold
outlet (located in lower corner of vestibule panel).
12- - Disconnect the gas supply piping from the unit.
13- - Disconnect the wiring to the gas valve.
14- - Disconnect the gas line at the union just below the
gas decoupler. Remove the gas valve, gas decoupler
and piping assembly.
15- - Remove the remaining gas piping from the fitting
at the vestibule panel.
IMPORTANT - - Hex head fitting contains gas dia-
phragm valve. Take care when handling this por-
tion of the piping assembly.
16- - Disconnect the blower motor wires from the con-
trol box.
17- - Disconnect the spark plug and sensor wires from
the plugs in the combustion chamber. (The access
plate is located to the left of the air decoupler box.)
18- - Remove the vest panel.
19- - Remove four
mounts from bottom of blower deck.
3DJH 
CAUTION
T o cool completely to room tem-
nuts holding rubber heat train