Fastrax Hellfire 900, Installation, Operation & Maintenance Instructions Manual

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I. MAINTENANCE
I.1 Thermostat Removal
1. Remove cover from thermostat box to gain access to
the thermostats. There are two thermostats. The high
limit, which has a red and a white wire connected to it, and
the cycling thermostat, which has a black and a blue wire,
connected to it.
CYCLING THERMOSTAT
(BLACK AND BLUE WIRES)
HIGH LIMIT THERMOSTAT
(RED AND WHITE WIRES)
Figure 1 – Thermostat Wire Connections
2. The wires are connected by means of quick disconnects.
To disconnect, grip the terminals on each side of the
connection and pull firmly.
3. Using a 9/16” socket, remove the 4 mounting bolts that
hold the enclosure to the sensor duct. Remove the
thermostat box and gasket.
4. Remove the two screws that fasten each thermostat to the
sensor duct. Remove thermostats.
5. The high limit and cycling thermostats are not
interchangeable. Each has unique connectors to prevent
interchange.
6. Reverse procedure to install.
I.2 Motor/Impeller/Base Removal
WARNING
WARNING. Risk of cutting fingers or hand. Disconnect
fan power prior to removing combustion chamber
access panel or air intake.
1. Remove the combustion chamber access panel to gain
access to the motor.
2. Open the motor junction box and disconnect all wiring and
conduit elbow.
3. Remove the four motor mount bolts and remove the motor/
impeller assembly from the combustion chamber.
4. Install replacement motor/impeller/base assembly,
following reverse order.
Motor Junction Box
Motor Mount Bolts
I.3 Impeller Removal
NOTE: Motor/impeller sets not match balanced by Thermon
Heating Systems, Inc. void future warranty claims.
NOTE:
Replacement of motor or impeller only. Dynamically
balance the motor/impeller and base assembly to
vibration levels of 0.2 in/sec or less in the bearing planes.
NOTE: Mark the position of the impeller on the shaft before
removing.
Third Empty Hole
Hub Set Screws
Tapered Hub
The impeller is fitted with a taper lock bushing. To remove
impeller from motor shaft:
1. Clamp the motor and anchor the impeller using a suitable
bar.
2. Remove the two hub set screws.
3. Insert a set screw into the third previously empty hole and
tighten.
4. Tap the outer half of the hub with a hammer and bar to
knock the impeller off the tapered hub.
5. Slide hub off shaft, then remove impeller.
6. To install the impeller, reverse sequence except step 4.