Lennox G26 series Installation Instructions Manual page 24

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- 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- Remove sensor wire from SureLight" control. Dis-
connect 2-pin plug from the ignitor.
10- Mark and disconnect pressure switch tubing from both
sides of the pressure switch.
11 - Loosen two screws holding gas manifold support at
vestibule panel.
12 - Remove four burner box screws at the vestibule panel
and remove burner box and gas valve/manifold as-
sembly 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 counter-
clockwise. 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.
15 - Disconnect the 2-pin plug from the combustion air in-
ducer at the blower deck. Remove four screws from
combustion air inducer and remove flue transition and
inducer 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 screws from the front cabinet flange at
the blower deck. Remove front screws from cabinet at
blower deck on left and dght sides. Cabinet sides must
be slightly spread to clear heat exchanger passage.
20- Remove screws along vestibule sides and bottom
which secure vestibule panel and heat exchanger as-
sembly to cabinet. Remove heat exchanger.
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 inducer. Check the plas-
tic orifice in the inducer inlet to make sure it has not
fallen out. See figure 1. Reconnect the 2-pin plug to
the wire harness. Re-install the flue transition in the
cabinet and re-attach the drain tube. Route the drain
tube below the combustion air inducer housing and to
the elbow on the cold header (collector) box trap. See
figure 36.
29 - Re-install condensate line with adapter to condensate
trap. Use fresh Teflon tape to ensure a leak-free joint.
Re-connect to condensate line outside of the unit.
30 - Re-install the burner box. Tighten the screws holding
the support bracket. It is important that the glass fiber
gasket not be damaged so it will provide a continuous
seal between the burner box and the vestibule panel
31 - With the pressure switch mechanism oriented on the
right, reconnect pressure switch tubing by connecting
the tubing from the burner box to the barbed fitting on
the bottom. Connect the tubing from the combustion
air inducer to the barbed fitting on the top. See figure
36.
32 - Reconnect the sensor and ignitor wires.
33 - Re-install top cap to unit.
34 - Re-instaU electrical connections to gas valve. Orange
wire to M1 and yellow wire to C2. Reconnect wires to
flame roll-out switch.
NOTE - Unit is polarity-sensitive. 120V supply wiring
must be installed correctly.
35 - Reconnect main gas line to gas valve.
36 - Re-install field make-up box if removed.
37 - Re-install exhaust pipe/flue collar and secure flue col-
lar to the unit top cap using existing screw. Insert the
bottom of the flue collar into the top of the flue transi-
tion and tighten hose clamp.
38 - Re-install intake pipe fitting to burner box with screws.
39 - Replace both upper and lower access panels.
40 - Refer to instruction on verifying gas and electrical con-
nections when re-establishing supply.
41 - Following lighting instructions from installation manu-
al, light and run unit for 5 minutes to ensure heat ex-
changer is clean, dry and operating safely.
Cleaning the Burner Assembly
1 - Turn off electrical and gas power supplies to fumaca.
Remove upper and lower furnace access panels.
2 - Disconnect the gas supply line to gas valve. Depend-
ing on gas plumbing installation,the gas manifold may
move aside enough that breaking the union may not
be necessary.
3 - Remove five screws from edges of burner box cover.
G26-50 units have only four screws.
4 - Loosen two screws on bottom of burner box front. The
cover is key holed at these screw point so screws do
not need to be removed. Pull off cover and set aside.
6 - Mark all gas valve wires and disconnect them from
valve.
7 - Mark and disconnect sensor wires from the burner box
at the ignition control. Disconnect 2-pin plug from the
ignitor at the burner box,
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