Service Instructions; Motor & Fan Wheel Assembly - L.B. White Therma Grow HW120 Owner's Manual And Instructions

18
Therma Grow™ Greenhouse Heaters
6. Review all heater markings (i.e. wiring diagram,
warnings, start-up, shut-down, troubleshooting,
etc.) at the time of maintenance for legibility. Make
sure none are cut, torn, or otherwise damaged. Any
damaged markings must be replaced immediately
by contacting the L.B. White Co., LLC Dataplates,
startup and shut-down instructions and warnings are
available at no cost. A nominal charge will be applied
for wiring diagrams.

Service Instructions

WARNING
Burn Hazard
■ Heater surfaces are hot for a period of time after
the heater has been shut down.
■ Allow the heater to cool before performing
service, maintenance, or cleaning.
■ Failure to follow this warning will result in burns
causing injury.
WARNING
Fire and Explosion Hazard
■ Do not disassemble or attempt to repair any
component part of the heater, including
regulators and gas hoses.
■ All components must be replaced if defects are
found.
■ Failure to follow this warning will result in gas
leaks.
■ Gas leaks cause fire or explosions, leading to
property damage, injury, or death.
1. Close the fuel supply valve to the heater and
disconnect the electrical supply before servicing
unless necessary for your service procedure.
2. Open end panels for access to heater components.
3. Disconnect the appropriate electrical leads for the
component being replaced.
4. The thermostat, and high limt switch can be tested by
jumpering the suspect part out of the electrical
circuit.:
-- Reconnect the electrical supply and open fuel
supply valves.
-- If the heater lights, the component is defective
and must be replaced.
-- Do not operate the heater with the component
jumpered. Replace the part immediately.
-- An alternate method for checking the
components is to perform a continuity check.
Owner's Manual • Therma Grow™
5. Do not jumper the air proving switch. If jumpered,
the ignition control will not allow heater operation.
Test the air proving switch for continuity. If defec-
tive, replace the switch
6. For reassembly, reverse the respective service
procedure. Ensure gas connections are tightened
securely.
7. After servicing, start the heater to ensure proper
operation. Check for gas leaks with approved leak
detectors.
8. Clean the heater's orifice with compressed air or a
soft, dry rag. Do not use files, drills, broaches, etc.
to clean the orifice. Doing so may enlarge the hole,
causing combustion or ignition problems. Replace
the orifice if it cannot be cleaned properly.
Motor and Fan Wheel Assembly
1. Remove the motor mounting plate screws and pull
the fan and motor assembly from the housing.
2. Loosen the square head set screw(s) on the fan
wheel.
3. Pull the fan wheel from the motor shaft. Use a
wheel puller if necessary.
4. Remove the four (4) nuts securing the motor to the
mounting plate.
a. Fan wheel to motor mount clearance is specified
in the table below..
b. Ensure fan set screw(s) are on the flats of motor
shaft when tightening.
FIG. 12
MOTOR MOUNT
PLATE
MOTOR
FAN WHEEL
CLEARANCE
1/8 IN.