FIGURE 21
STATIC PRESSURE TEST
Page 30
C−External Static Pressure
1 − Tap locations shown in figure 21.
2 − Punch a 1/4" diameter hole
in supply and return air ple-
nums. Insert manometer
hose flush with inside edge
of hole or insulation. Seal
around the hose with per-
magum. Connect the zero
end of the manometer to the
discharge (supply) side of the system. On ducted sys-
tems, connect the other end of manometer to the re-
turn duct as above. For systems with non−ducted re-
turns, leave the other end of the manometer open to
the atmosphere.
3 − With only the blower motor running and the evaporator
coil dry, observe the manometer reading. Adjust blow-
er motor speed to deliver the air desired according to
the job requirements.
4 − External static pressure drop must not be more than
0.5" W.C.
5 − Seal around the hole when the check is complete.
D−Blower Taps SureLight 56L83 & 97L48
Blower speed tap changes are made on the SureLight con-
trol board. See figure 6. Unused taps must be secured on
dummy terminals "PARK M1" and or "PARK M2" on the
SureLight board. The heating tap is connected to the "ACB
HEAT " terminal and the cooling tap is connected to the
"ACB COOL" terminal. The continuous blower tap is con-
nected to the "ACB LOW" terminal.
To change existing heat tap, turn off power then switch out
speed tap on "ACB HEAT" with tap connected to "PARK
M1" or "PARK M2". See wiring diagram for for blower motor
tap colors for each speed.
E−Blower Taps SureLight 69M15
Blower speed tap changes are made on the SureLight con-
trol board. See figure 8. Unused taps must be secured on
dummy terminals "PARK" on the SureLight board. The
heating tap is connected to the "HEAT " terminal and the
cooling tap is connected to the "COOL" terminal. The con-
tinuous blower tap is connected to the "FAN" terminal.
To change existing heat tap, turn off power then switch out
speed tap on "HEAT" with tap connected to one of two
"PARK" terminals. See wiring diagram for for blower motor
tap colors for each speed.
VI−MAINTENANCE
At the beginning of each heating season, the system
should be checked as follows:
A−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.
B− Heat Exchanger and Burners
Cleaning the Heat Exchanger and Burners
NOTE−Use papers or protective covering in front of fur-
nace while cleaning furnace.
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" diameter steel wire cable and a 1/4" diameter wire
brush. These items are available at a hardware store. In-
sert wire end of brush into the open end of the spring cable.
Crimp the cable around the brush so that the brush is se-
cured and will not come off during cleaning. Attach the oth-
er end of the cable to the reversible drill to complete the tool
for cleaning the heat exchanger. See figure 1 for parts ar-
rangement when disassembling furnace.
1 − Turn off both electrical and gas power supplies to fur-
nace.
2 − Remove flue pipe and top cap from unit. Mark and dis-
connect wiring from prove switch and combustion air
inducer.
FIGURE 22
G50UH(X) BURNER & HEAT
EXCHANGER REMOVAL
HEAT EXCHANGER
BURNER BOX ASSEMBLY
3 − Remove four screws securing the combustion air in-
ducer. Carefully remove the combustion air inducer and
prove switch together as a unit to avoid damaging blow-
er gasket. If gasket is damaged, it must be replaced to
prevent leakage.
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