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CERAMIC
BAFFLE
CLIP
HEAT EXCHANGER
TUBES
NOTE: One baffle and clip will be in each upper tube of the heat exchanger.
Fig. 48 — Removing Heat Exchanger Ceramic
Baffles and Clips
PRESSURE SWITCH (48P MODULATING GAS ONLY)
Inspect the riveted surface of the pressure fitting (see Fig. 45) by
removing the flue box cover. Clean as necessary to ensure the
proper function of the combustion air proving switch. When reas-
sembling flue box, ensure that both ends of pressure switch tubing
are tight pressed into fitting and pressure switch, respectively.
COMBUSTION-AIR BLOWERS (48P ONLY)
Clean periodically to assure proper airflow and heating efficiency.
Inspect blower wheel every fall and periodically during heating
season. For the first heating season, inspect blower wheel bi-
monthly to determine proper cleaning frequency.
To inspect blower wheel, remove heat exchanger access panel.
Shine a flashlight into opening to inspect wheel. If cleaning is re-
quired, remove motor and wheel assembly by removing screws
holding motor mounting plate to top of combustion fan housing
(Fig. 49). The motor and wheel assembly will slide up and out of
the fan housing. Remove the blower wheel from the motor shaft
and clean with a detergent or solvent. Replace motor and wheel
assembly.
Fig. 49 — Combustion Blower Removal
ECONOMIZER DAMPER MOTOR(S)
On units so equipped, the economizer motor(s) is located in the
mixing box section. Access to it is through the door labeled FIL-
TER SECTION.
CONDENSER FANS AND FAN MOTORS
Remove the wire fan guard on top of the unit to gain access to the
condenser fans and motors.
25% OUTDOOR-AIR DAMPER
Access to adjust the damper is through the hoods. Remove filters
to gain access into unit to adjust linkage arms.
MODULATING POWER EXHAUST DAMPER MOTOR
The modulating power exhaust damper motor is located in the re-
turn-air end of the unit.
IMPORTANT: When replacing panel, be sure to properly secure
it in order to prevent water from being drawn into the unit.
The motor is accessed through the small door below the side econ-
omizer hoods on the left side of the unit. See Fig. 41.
RETURN-AIR FILTERS
Access to these filters is through the door marked FILTER SEC-
TION. Filters in upper and lower bag filter tracks can only be re-
moved from the right side of the unit.
Adjustments
RETURN FAN MOTOR PLATE
Adjust using a 3/4 in. wrench on the adjusting bolts:
1.
Loosen holddown bolts. (See Fig. 50).
2.
Turn the adjusting bolts to move the motor mounting plate
toward or away from the fan to loosen or tighten the belts.
Make the same number of turns to each bolt.
3.
Re-tighten holddown bolts.
Fig. 50 — Return Fan Motor
Plate Adjustment
160
HOLDDOWN BOLTS
HOLD-
DOWN
BOLTS
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Troubleshooting
