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16β Disconnect 9-pin plug from the blower compartment at
the blower deck.
17β Remove 9-pin plug above the blower deck.
18β Remove the limit switch and the pressure switch from
the vestibule panel.
19β 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 passage.
20β 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.
21β Back wash heat exchanger with soapy water solution
or steam. If steam is used it must be below 275ξF
(135ξC) .
22β Thoroughly rinse and drain the heat exchanger. Soap
solution can be corrosive so take care that entire as-
sembly is completely rinsed.
23β Reβinstall 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 open-
ing.
24β Re-secure the supporting screws along the vestibule
sides and bottom to the cabinet.
25β Re-install cabinet screws on sides and front flange at
blower deck.
26β Re-install the limit switch and pressure switch (β75 unit
will have a second switch) on the vestibule panel.
27β Re-install 9-pin plug to blower deck and connect it to
the 9-pin plug from below the blower deck.
28β 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 3-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 31.
29β Re-install condensate line with adapter to condensate
trap. Use fresh Teflon tape to ensure a leakβfree joint.
Re-connect to condensate line outside of the unit.
30β 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.
31β Reconnect pressure switch tubing by connecting the
tubing from the burner box to the barb on the bottom
and the tubing from the combustion air blower to the
barb on the top. See figure 31.
NoteβG32Vβ75 units will have two pressure switches.
32β Reconnect the sensor and ignitor wires.
33β Re-install top cap to unit.
34β Re-install electrical connections to gas valve. Brown
wire to H1, yellow wire to C2 and orange wire to M. Re-
connect wires to flame roll-out switch.
NOTE β Unit is polarity-sensitive. 120V supply wiring
must be installed correctly.
35β Reconnect main gas line to gas valve.
36β Re-install field make-up box if removed.
37β 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 transition
and tighten hose clamp.
38β Re-install intake pipe fitting to burner box with screws.
39β Replace both upper and lower access panels.
40β Refer to instruction on verifying gas and electrical con-
nections when re-establishing supply.
41β 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 β Turn off electrical and gas power supplies to furnace.
Remove upper and lower furnace access panels.
2 β 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 β Remove five (5) screws from edges of burner box cov-
er.
4 β Loosen two (2) 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 β Mark gas valve wires and disconnect them from valve.
7 β Mark and disconnect sensor wire from the burner box
at the SureLight control. Disconnect 2-pin plug from
the ignitor at the burner box.
8 β Loosen two (2) screws at the gas manifold support
bracket.
9 β Pull on the left side of the gas manifold and follow with
tension to the right side. The manifold support bracket
will be free of the mounting screws on the vestibule
panel. Set the gas manifold/gas valve assembly aside.
Take care not to damage foam gaskets on each end of
the gas manifold.
10β Using a 1/4" nut driver, remove the burner mounting
screws from underneath the burners.
11β While supporting ignitor and sensor lines at the grom-
met, grasp burners and simultaneously pull burners
and grommet out of the burner box.
12β Remove ignitor and sensor assemblies from burners
using a 1/4" nut driver to remove two screws from each
bracket.
13β Clean burner by running a vacuum with a soft brush at-
tachment over face of burners. Visually inspect inside of
burners and crossovers for any blockage caused by for-
eign matter. Remove any blockage.
14β Re-install ignitor and sensor bracket assemblies on
burners.