Service; Cleaning Heat Exchanger; Blower; Exhaust And Air Intake Pipes - Lennox G71MPP-36B-070 Installation Instructions Manual

AWARNING
At the beginning of each heating season, system should be
checked as follows by a qualified service technician:
Blower
Check the blower wheel for debris and clean if necessary.
The blower motors are prelubricated for extended bearing
life, No further lubrication is needed,
AWARNING
Filters
All G71MPP filters are installed external to the unit. Filters
should be inspected monthly. Clean or replace the filters
when necessary to ensure proper furnace operation. Table
3 lists recommended filter sizes.
Exhaust and air intake pipes
Check the exhaust and air intake pipes and all connections
for tightness and to make sure there is no blockage,
Electrical
1 - Check all wiring for loose connections.
2 - Check for the correct voltage at the furnace (furnace
operating).
3 - Check amp-draw on the blower motor.
Motor Nameplate Actual
Winterizing and Condensate Trap Care
1 - Turn off power to the unit,
2 - Have a shallow pan ready to empty condensate water.
3 - Remove the drain plug from the condensate trap and
empty water. Inspect the trap then reinstall the drain
plug and refill trap with water,
Cleaning Heat Exchanger
If cleaning the heat exchanger becomes necessary, follow
the below procedures and refer to figure 1 when disassem-
bling unit. Use papers or protective covering in front of fur-
nace while removing heat exchanger assembly.
1 - Turn off electrical and gas supplies to the furnace.
2 - Remove the upper and lower furnace access panels,
3 - Disconnect the 2-pin plug from the gas valve,
4 - Remove gas supply line connected to gas valve, Re-
move gas valve/manifold assembly,
5 - Remove sensor wire from sensor, Disconnect 2-pin
plug from the ignitor.
6 - Disconnect wires from flame roll-out switches.
7 - Remove burner box cover and remove four burner box
screws at the vestibule panel and remove burner box,
Set burner box assembly aside.
NOTE - G71MPP-135 units are secured to the vesti-
bule panel by two additional screws. These screws
must be removed for servicing; however it is not nec-
essary to replace the screws.
NOTE- If necessary, clean burners at this time. Follow
procedures outlined in Burner Cleaning section.
8 - Loosen three clamps and remove flexible exhaust tee.
9 - Remove 3/8 inch rubber cap from condensate drain
plug and drain. Replace cap after draining.
10 - Disconnect condensate drain line from the conden-
sate trap, Remove condensate trap (it may be neces-
sary to cut drain pipe), Remove screws that secure
condensate collars to either side of the furnace and re-
move collars. Remove drain tubes from cold end
header collector box.
11 - Disconnect condensate drain tubing from flue collar,
Remove screws that secure both flue collars into
place. Remove flue collars, It may be necessary to cut
the exiting exhaust pipe for removal of the fittings,
12 - Mark and disconnect all combustion air pressure tub-
ing from cold end header collector box.
13 - Mark and remove wires from pressure switches. Re-
move pressure switches, Keep tubing attached to
pressure switches,
14 - Disconnect the 4-pin plug from the combustion air in-
ducer, Disconnect the two wires to the backup secon-
dary limit, if applicable. Remove four screws which se-
cure combustion air inducer to collector box, Remove
combustion air inducer assembly, Remove ground
wire from vest panel.
15 - Remove electrical junction box from the side of the fur-
nace.
16 - Mark and disconnect any remaining wiring to heating
compartment components. Disengage strain relief
bushing and pull wiring and bushing through the hole
in the blower deck.
17 - Remove the primary limit from the vestibule panel.
18 - Remove two screws from the front cabinet flange at
the blower deck. Spread cabinet sides slightly to allow
clearance for removal of heat exchanger.
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