Cleaning Heat Exchanger And Burners - Lennox G26Q2-50 Unit Information

2 - Reusable foam filters used with the G26 can be
washed with water and mild detergent. When dry, they
should be sprayed with filter handicoater prior to rein-
stallation. Filter handicoater is RP Products coating
no. 418 and is available as Lennox part no. P-8-5069.
3 - If replacement is necessary, order Lennox part no.
31J81 for 14" x 25" (356 x 635mm) filter for G26-50
and -75 units and P-8-7831 for 20" x 25" (508 x
635mm) filter for G26Q4/5-75,G26-100 and -125
units.
B-Cleaning Heat Exchanger and Burners
If cleaning the heat exchanger becomes necessary, follow
the below procedures and refer to figure 1 when disas-
sembling unit. Use papers or protective covering in front of
furnace while removing heat exchanger assembly.
1 - Turn off electrical and gas power supplies to furnace.
2 - Remove upper and lower furnace access panels.
3 - Remove four (4) screws around air intake fitting and
lift intake pipe up and away.
4 - Loosen hose clamp securing top of flue transition to
bottom of flue collar. Remove screw securing flue col-
lar to top cap and lift exhaust pipe and flue collar up
and away.
5 - If electrical field make-up box is located inside the
unit, it must be removed.
6 - Remove gas supply line connected to gas valve.
7 - Mark all gas valve wires and disconnect them from
valve. Mark and remove wires from flame roll-out
switch.
8 - Remove top cap of unit.
9 - For -1 and -2 units, mark and disconnect spark and
sensor wire from ignition control. For -3 units, remove
sensor wire from SureLight control. Disconnect 2-pin
plug from the ignitor.
10- Mark and disconnect pressure switch tubing from
both sides of the pressure switch.
11- Loosen two (2) screws holding gas manifold support
at vestibule panel.
12- Remove four (4) burner box screws at the vestibule
panel and remove burner box and gas valve/manifold
assembly with bracket.
13- Drain condensate trap. Disconnect condensate line
from the outside of unit. Remove condensate line
from condensate trap by turning the adapter fitting
counterclockwise. The fitting has standard right hand
threads.
14- Disconnect the drain hose from the flue transition to
the elbow on the cold header (collector) box trap. On
-1 and -2 units remove two (2) screw from flue "Y" trap
at cabinet from door flange.
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15- Disconnect the 2-pin plug from the combustion air
blower at the blower deck. Remove four (4) screws
from combustion air blower and remove flue transition
and blower assembly from cabinet. Take care not to
lose the combustion air orifice.
16- Disconnect 9-pin plug from the blower compartment
at the blower deck.
17- Remove 9-pin plug above the blower deck.
18- Remove the limit switch and the pressure switch from
the vestibule panel.
19- Remove two (2) screws from the front cabinet flange
at the blower deck. Remove front screws from cabinet
at blower deck on left and right sides. Cabinet sides
must be slightly spread to clear heat exchanger pas-
sage.
20- Remove screws along vestibule sides and bottom
which secure vestibule panel and heat exchanger as-
sembly to cabinet. Remove heat exchanger then re-
move cold end header box. Remove baffles from con-
denser tubes.
21- Back wash heat exchanger with soapy water solution
or steam. If steam is used it must be below 275_F
(135_C) .
22- Thoroughly rinse and drain the heat exchanger. Soap
solution can be corrosive so take care that entire as-
sembly is completely rinsed.
23- Re-install heat exchanger into cabinet making sure
that the clamshells of the heat exchanger assembly
are resting in the notches of the support located at the
rear of the cabinet. This can be viewed by removing
the indoor blower and examining through the blower
opening.
24- Re-secure the supporting screws along the vestibule
sides and bottom to the cabinet.
25- Re-install cabinet screws on sides and front flange at
blower deck.
26- Re-install the limit switch and pressure switch on the
vestibule panel.
27- Re-install 9-pin plug to blower deck and connect it to
the 9-pin plug from below the blower deck.
28- Re-install the combustion air blower. Be careful that
the plastic orifice on the blower inlet has not fallen out.
See figure 1. Reconnect the 2-pin plug to the wire har-
ness. Re-install the flue transition in the cabinet and
re-attach the drain tube. Route the drain tube below
the combustion air blower housing and to the elbow
on the cold header (collector) box trap. See figure 23.
29- Re-install condensate line with adapter to conden-
sate trap. Use fresh Teflon tape to ensure a leak-free
joint. Re-connect to condensate line outside of the
unit.
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