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e.) Place the fan switch in the auto position.
f.) The fan should go off.
g.) Set the temperature control thermostat to a
setting above the current room temperature.
h.) The fan and heater should operate. If the room
temperature is high and the installation is above
3,300 feet (1000m), the unit heater may cycle on
the thermal high limit cutouts of the motor or the
heater.
i.) Check out and report any unusual or
questionable operating characteristics, such as
noise, vibration, loss of fluid, etc.
Note that crackling noises coming from the heat
exchanger during warm up are normal.
j.) Set the fan switch and temperature control
thermostat to the desired operating positions.
B. Normal Operation:
Prior to the start of the heating season, perform the electrical
and mechanical steps outlined in the section titled
"maintenance".
a.) Perform the Operation steps for the applicable
temperature control option.
b.) Place all switches in their normal operating position
and place the unit heater in service.
MAINTENANCE
Maintenance and repair must be performed by qualified
personnel only.
A. Electrical:
1. Inspect all terminal connections, contactor and
conductor insulation for damage, looseness, fraying,
etc., as applicable. Tighten any loose terminals and
replace or repair wire with damaged or deteriorated
insulation. If contactor contacts are badly pitted,
welded together, or burned, replace the contactor.
Check all explosion-proof conduit for visible damage
and tightness.
2. If reduced heat output is suspected, perform the
mechanical checks. If low heat output is still suspected
after completing the mechanical checks, verify the
condition of the heating elements by using an amperage
meter to check the current draw of each input line. All
input lines should draw approximately equal current
which should agree with nameplate rating. If they do
not, one or more of the heating elements could be
burned out and the heater/core assembly should be
replaced.
3. The electric motor is permanently lubricated and
thermally protected. Check for smooth and quiet
running at all inspections. Replace motor if excessive
bearing play is detected. Contact the factory for
instructions.
B. Mechanical:
1. Never attempt to fill, drain or check the liquid level of
the heat exchanger or check the action of the pressure
relief valve. Contact the factory for instructions.
2. The explosion-proof control box is designed with
threaded joints and metal-to-metal contact at the lid or
cover joints to prevent an explosion. Do not attempt to
install gasket material of any type at these joints. A
light coating of anti-seize compound is applied to the
threads to prevent seizing.
3. Annually check the tightness of all visible bolts and
nuts, in particular the support structure bolts and nuts.
Similarly check the motor mounting bolts and nuts.
4. Periodically, check the motor, fan and heater core fins
for cleanliness. A dirty heat exchanger can cause the
unit to over heat and cycle on the thermal cutouts. If
the dirt is loose dust, clean with a vacuum or by air jet.
If the dirt can't be vacuumed or blown off, use a warm
water spray directed to the inlet side of the heat
exchanger then to the outlet side. A soft bristled brush
may be required to loosen stubborn deposits. Be
careful not to bend the aluminum fins on the heat
exchanger or the fan blade propeller. Allow unit to dry
before re-energizing.
5. Check louvers for position tightness and equal angle
settings. Check motor and fan for smooth running
operation. Any unusual noise or vibration must be
investigated and rectified.
6. Should there be any evidence of fluid leakage from the
heater core, the heater should be repaired immediately.
The heater will not operate properly with a low fluid
level. Contact the factory for replacement core.
REPAIR AND REPLACEMENT
Maintenance and repair must be performed by qualified
A. Replacing the Heat Exchanger Core:
The heat exchanger core is not field repairable.
Contact factory for replacement.
1. Disconnect the heater electrical power supply,
unwire and lower the heater from it's
mounting location. Set heater face down on a
table or on the floor.
2. Remove the cabinet bottom, cabinet top,
wiring and heater enclosure covers.
3. Disconnect all heater wires from the contactor
in the wiring enclosure. Disconnect the control
wiring from thermal cutout.
4. Thread conduit into wiring enclosure to
disconnect the heater terminal box.
5. With an assistant supporting the weight of the
heat exchanger, remove the 3 heat exchanger
mounting bolts. Carefully remove the heat
exchanger out of the bottom of the cabinet.
6. Locate rating tag on the heat exchanger and
verify that electrical ratings of the core to be
installed match the electrical ratings on the
heater nameplate.
7. To reinstall, slide the core through the bottom
of the cabinet while an assistant lines up and
installs the 3 heat exchanger mounting bolts.
8. Guide the heater lead wires back into the
wiring enclosure.
9. Reconnect the heater lead wires to the
contactor and the conduit.
10. Reattach the cabinet bottom and enclosure
covers before mounting heater and energizing.
Page 5 of 25
personnel only.
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