Rev. B 8/14 MASTERTEMP
®
125 Pool and Spa Heater Installation and User’s Guide
43
Diagnostic LED's: SFS
NO
(HD )
NO
(Basic)
NO
Reset power to Heater and
retry. Heater should
fire.
Does the Digital
Temperature Display show
Error Code “E05” or “E06”
?
Heater starts and runs OK,
but temperature of exhaust
climbs to 450˚–500˚ in 3–5
minutes.
Heater starts after several
tries, exhaust temperature
stays below 250˚.
OR
Heater doesn’t start at all
(exhaust stays
cold).
Check pressure and volume
of fuel
supply
Check the J3 and J6
connectors for corrosion/
looseness on the male
pins.
Check continuity in wiring
harness between Control
Board and Probe.
Continuity
OK?
Disconnect the sensor and
check continuity across its
terminals. Resistance
should be 3.5-4.0 mega-
ohms.
= open circuit;
0 = shorted.
Does sensor check
OK?
Clean/tighten pins as
needed.
Reset power to Heater
and retry. Heater should
fire.
NOT OK
NO
NO
NO
NO
NO
SFS "on"
Replace Stack Flue Sensor
Correct Fuel Supply, reset
Heater and retry. Heater
should fire correctly
.
Repeat checks on fuel
supply, Thermal Regulator,
check for correct orifices,
etc.
DONE
DONE
YES
YES
YES
YES
NO
NO
YES
NO
OK
YES
Replace Heater
Control
Board.
Replace Heater
Membrane
Pad.
Reset power to Heater and
retry. Heater should
fire.
Check Heat Exchanger Coil for
leaks, liming, soot, or low flow
.
Correct problem;
Heater should fire
.
Check Heat Exchanger
Coil for leaks, liming, soot,
or low flo
w.
Check Thermal
Regulator: Open at
120˚?
Check Thermal-Regulator:
Seats
correctly?
DONE
NO
DONE
Replace Heater Membrane Pad.
Replace Heater Control Board.
Reset power to Heater and
retry. Heater should
fire.
Reset power to Heater and
retry. Heater should
fire.
DONE
NO
YE
S
YE
S
DONE
NO
Section 5. Troubleshooting
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