Gas-Fired Furnaces (Duct And Rack Systems); Energy Recovery Wheel; Zeroing The Minihelic Gage Before Start; Service - Carrier Aero 39MN Series Installation, Start-Up And Service Instructions Manual

2. Turn off electrical supply to unit at disconnect switch.
3. Turn off manual gas supply.
4. Disconnect manifold and inlet pressure taps and re-install
pipe plugs.
5. Replace vestibule access panel or close door.

Energy Recovery Wheel

CAUTION
Keep hands away from rotating wheel. Contact with
rotating wheel can cause physical injury.
1. By hand, turn the wheel clockwise (as viewed from the
pulley side), to verify that the wheel turns freely
through a full 360-degree rotation.
2. Before applying power to the drive motor, confirm that
the wheel segments are fully engaged in the wheel
frame and that the segment retainers are completely
fastened. (See Fig. 160.)
3. With hands and objects away from moving parts, acti-
vate the unit and confirm wheel rotation. The wheel
rotates clockwise (as viewed from the pulley side).
4. If the wheel has difficulty starting, turn the power off
and inspect for excessive interference between the
wheel surface and each of the four (4) diameter seals.
To correct, loosen the diameter seal adjusting screws
and back adjustable diameter seals away from the sur-
face of the wheel, apply power to confirm that the
wheel is free to rotate, then re-adjust and tighten the
hub and diameter seals according to the instructions in
the Service section.
5. Start and stop the wheel several times to confirm seal
adjustment and to confirm that the belt is tracking
properly on the wheel rim (approximately
outer edge of rim).
2 ROTATE AWAY
FROM WHEEL RIM
SEGMENT
RETAINER
CATCH
1
PUSH
TOWARD
CENTER
WHEEL RIM
a39-2379
Fig. 160 — Segment Retainer

ZEROING THE MINIHELIC GAGE BEFORE START

UP — If the Minihelic* gage needs to be removed or re-
placed, after installation, it may need to be zeroed before
placing in operation. If re-zeroing is required, firmly hold
the case of gage with one hand and unscrew the front cover
with the palm of the other hand in a counterclockwise direc-
tion. If difficult to loosen, place a small sheet of rubber be-
tween the cover and the palm of the hand. Zero-adjust screw
is located behind the scale at the pair marked "zero." Use a
hex/allen wrench and adjust until pointer is on zero. This
must be done with both pressure connections vented to at-
mosphere and the gage oriented in the final mounting posi-
tion. Replace cover.
*Minihelic is a registered trademark of Dwyer Instruments Inc.
Electric shock hazard. Disconnect power before entering or
servicing.
More than one disconnect switch may be required to de-
energize the equipment.

General

1. Review Safety Considerations at beginning of these in-
2. To make speed measurements, use a strobe-style ta-
Electric Heaters —
ating season or whenever unit is serviced, check field and fac-
tory-made electrical connections for tightness. Also periodical-
ly clean filters, fan, airways, ductwork, grilles, and registers as
required. Differential air pressure switch is factory set to open
at 0.07 in. wg, close at 0.05 in. wg and requires no adjustment.
Refer to the Troubleshooting section for more information.
Heater electrical data is shown in Table 40.
Gas-Fired Furnaces (Duct and Rack Sys-
tem) —
tion check.

INSPECTION

1. The duct furnace or furnace module should be inspect-
1 / in. from
4
2. Label all wires prior to disconnection when servicing
3. Inspect burners, heat exchanger, induced draft fan and
SPOKE
4. Check the heat exchanger for cracks. If any are present,
5. Check the attachment points of the duct furnace to the
CENTER OF
WHEEL
6. Check the automatic gas valve to ensure that the gas
7. Check wiring connections to be sure they are secure, and
If any of the original wiring needs to be replaced, it must be
replaced with wiring materials suitable for 221°F (105°C).
Unsuitable wiring materials may cause equipment damage.

OPERATION CHECK

1. Turn on power to the unit and set thermostat or heat con-
2. Check for proper start-up and ignition of the single unit or
181

SERVICE

CAUTION
structions. Good safety habits are important tools
when performing service procedures.
chometer or calculate per Step 7 of Start-Up, Checklist
for Airfoil and Forward-Curved Fans (page 176).
At least once a year at start of oper-
Follow these procedures for inspection and opera-
ed annually by a qualified service agency. The condi-
tion of the burners, heat exchanger, draft inducer, vent
system, operating controls and wiring should be deter-
mined. Check for obvious signs of deterioration, accu-
mulation of dirt and debris, and heat or water related
damage. Any damaged or deteriorated parts should be
replaced before the unit is put back into service.
unit, Wiring errors can cause improper or dangerous op-
eration. Verify proper operation after servicing.
vent ducts and clean as necessary.
replace heat exchanger before putting unit back into ser-
vice.
cabinet to verify that they are air-tight. For a rack system
module, check the attachment points to the cabinet or
ducts to verify that they are air-tight.
valve seat is not leaking.
inspect wiring for any deterioration.
CAUTION
troller to call for heat, allowing duct furnace or heater as-
sembly module to operate.
each furnace in the heater assembly module. See the