P/N 471593
Rev. C 11-1-01
32
Possible Cause
Remedy
Heater will not come on
Automatic ignition system fails
Check if electrical connections are
correct and securely fastened –
If YES, call serviceperson.
Pump not running
Place pump in operation
Pump air locked
Check for leaks
Filter dirty
Clean filter
Pump strainer clogged
Clean strainer
Defective wiring or connection
Repair or replace wires
Defective pressure switch
Replace switch
Defective gas controls
Call serviceperson
On-Off switch in "OFF" position
Turn switch to "ON"
Heater Short Cycling
(Rapid On and Off Operation)
Insufficient water flow
Clean filter and pump strainer
Defective wiring
Repair or replace wiring
Defective flow valve or out of adjustment
Call serviceperson
Defective hi-limit and/or thermostat
Call serviceperson
Heater Makes Knocking Noises,
Make sure all valves on system are open
Heater operating after pump has shut off
Shut off gas supply and call serviceperson
Heater exchanger scaled
Shut off gas supply and call serviceperson
Troubleshooting - General
CAUTION
Please consult the latest edition of the “MiniMax NT Low NOx Service Manual” for complete service and
repair instructions. Repairs should only be attempted by properly trained service personnel.
