11
Supreme Exhaust Fan Service (cont.)
To Replace Motor
CAUTION! MAKE SURE POWER IS TURNED OFF AT THE DISCONNECT SWITCH PRIOR TO CHANGING MOTOR.
Open the motor cover and install the cover support arm. Loosen the belt tension lock nuts and remove the belt. Remove
the motor J-box cover. Disconnect the motor wiring in the motor J-box. Disconnect the conduit connector from the motor J-
box. Loosen the pulley set screw and remove the pulley key. Pry the pulley off the motor shaft. Remove the four bolts, nuts
and washers securing the motor to the motor mounting plate. Remove the motor. Install the new motor using the four bolts,
nuts and washers. Install the pulley key in the motor shaft and re-install and align the pulley (see “Pulley Alignment”).
Tighten the pulley key set screw. Insert the motor wiring and the conduit connector into the motor J-box and fasten the con-
duit connector. Reconnect the motor wiring, making sure the connections are made in compliance with the wiring diagram
on the motor. Leave J-box cover off at this time. Re-install the belt and adjust the belt tension. Turn the disconnect switch
“ON” and momentarily energize the exhaust fan motor to verify correct rotation. If rotation is incorrect, turn the disconnect
switch “OFF” and reverse motor rotation. Turn “ON” disconnect switch. Verify the motor rotation is now correct by, again,
momentarily energizing the fan motor. Using the motor leads in the motor J-box, take a correct reading with an appropriate
instrument to verify that the motor is running within the nameplate amperage range and is not overloaded. Re-install the
motor J-box cover. With the fan “ON”, visually inspect that all is in proper working order. Turn “OFF” the disconnect switch.
Replace the motor cover support arm in its retainer clip, close the cover and tighten the cover wing nuts. Turn the discon-
nect switch “ON”.
To Increase Exhaust Air Delivery
By increasing the blower wheel speed. Prior to accomplishing this procedure, it is important to check these items:
1. With the exhaust fan running, remove the motor J-box cover and take current readings on each leg of the motor sup-
plying conductors to verify that there is additional motor amperage available to increase the motor load. Inspect the
motor nameplate to ascertain the maximum motor full load amps. DO NOT exceed this value. If additional amperage is
available, leave the motor J-box cover off to take additional readings.
2. Turn “OFF” the motor. Visually inspect the adjustable motor drive pulley to verify that there is additional adjustment
available to close the pulley groove to speed up the blower wheel. If the “V” belt is riding at the top of the pulley, there
is no adjustment available. The pulley must be changed to the next larger size pulley.
3. Check the position of the belt tensioning bolts at the motor mounting plate to verify that additional adjustment is avail-
able for the increased belt length created by the pulley adjustment. If the belt will be out of range for the adjustment,
the next longer size belt must be installed.
To Adjust the Pulley
Remove the fan “V” belt (see “How To Replace Belt”). Loosen the allen screw at the hub of the pulley and remove the key.
Rotate the top of the pulley clockwise to close the belt groove 1/2 turn, 1 turn, 1-1/2 turns or 2 turns as required to obtain
the required adjustment. Re-install the key and tighten the key set screw. Re-install the “V” belt and adjust the belt tension.
Turn the fan “ON” and check the motor full load amps to verify that the motor is not overloaded. Re-install the motor J-box
cover.
To Decrease Exhaust Air Delivery
By decreasing the blower wheel speed. Follow the above procedure except…rotate the top of the pulley counter-clockwise
to open the belt groove as required to obtain the required adjustment.
NOTE: The ”V” belt must not ride on the bottom or flat of the pulley. If this condition occurs during the adjustment, change
the pulley to the next smaller size. This may also require changing the “V” belt to the next shorter size.
Re-assemble all parts as noted above and turn “ON” the exhaust fan.
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