Page 33
G50UH Series
Service
WARNING
Disconnect power before servicing unit.
CAUTION
Label all wires prior to disconnection when servicing
controls. Wiring errors can cause improper and dan-
gerous operation. Verify proper operation after ser-
vicing.
At the beginning of each heating season, a licensed profes-
sional technician (or equivalent) should check the system
as follows:
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.
WARNING
The blower access panel must be securely in place
when the blower and burners are operating. Gas
fumes, which could contain carbon monoxide, can
be drawn into living space resulting in personal inju-
ry or death.
Filters
All G50UH(X) filters are installed external to the unit. Filters
should be inspected monthly. Clean or replace the filters
when necessary to ensure that the furnace operates prop-
erly. Replacement filters must be rated for high velocity air-
flow. Table 1 lists recommended filter sizes.
Flue And Chimney
Check the flue pipe, chimney and all connections for tight-
ness 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__________
Cleaning the Heat Exchanger and Burners
NOTE − Use papers or protective covering in front of the fur-
nace during cleaning.
Cleaning the heat exchanger requires a steel spring
snake," a reversible drill and a vacuum cleaner. The steel
spring snake may be constructed by purchasing a 4 ft. long
by 1/4 inch diameter steel wire cable and a 1/4 inch diame-
ter wire brush. These items are available at a hardware
store. Insert wire end of brush into the open end of the
spring cable. Crimp the cable around the brush so that the
brush is secured and will not come off during cleaning. At-
tach the other end of the cable to the reversible drill to com-
plete the tool for cleaning the heat exchanger.
1 − Turn off both electrical and gas power supplies to fur-
nace.
2 − Remove flue pipe and top cap from the unit. Label the
pressure switch wires, then disconnect them.
3 − Remove the four screws that secure the combustion
air inducer. Carefully remove the combustion air induc-
er to avoid damaging blower gasket. If gasket is dam-
aged, it must be replaced to prevent leakage. See fig-
ure 30.
G50UH(X) BURNER & HEAT
EXCHANGER REMOVAL
FIGURE 30
HEAT EXCHANGER
BURNER BOX ASSEMBLY
4 − Remove the collector box located behind the combus-
tion air inducer. Be careful with the collector box gas-
ket. If the gasket is damaged, it must be replaced to
prevent leakage.
5 − Label the wires from gas valve and rollout switches,
then disconnect them.
6 − Disconnect gas supply piping. Remove four screws se-
curing the burner manifold assembly to the vestibule
panel and remove the assembly from the unit.
7 − NOx units only − Remove the three screws that attach
the NOx insert to the corbel at the entrance to each
heat exchanger section. Carefully remove the NOx in-
sert from each section. See figure 31.
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