21-40-01
99M90
Page: 6-6
Issued: May 9, 2012
Rev. New
I-Series Combustion Heater
Owners Manual
6.5 Testing
Miscellaneous and Optional Components (cont’d)
A. Test ventilating air and combustion air motors for correct rpm and current draw:
1.
Connect motor to correct voltage power supply (12 or 24 volts DC). Rotation should be
counter clockwise when viewed from the shaft end.
2.
Both motors should rotate at approximately 7500 rpm at rated voltage. Current draw for 12
volt motors is approximately five amps and for 24 volt motors is approximately 2.9 amps. This
can be tested using a mechanical or optical tachometer.
3.
If current draw is excessive, or if speed is too low, replace the brushes. Recheck both
current draw and rpm after brushes are properly run in. (Refer to Para 6.3 for run in.)
4.
If after replacing brushes, operation is still unsatisfactory, replace the motor.
The motor checks described above should be made without the blower housing attached, for both
the ventilating air and combustion air motors.
