Rev. B 8/14 MASTERTEMP
®
125 Pool and Spa Heater Installation and User’s Guide
39
Heater Will Not Fire - B
Start
Increase POOL/SPA tempera-
ture setting on Membrane
Pad above actual water tem-
perature. Heater should fire
on demand for heat. If not,
and no other red LED’s light,
replace Control
Board.
Service pump/filter and elimi-
nate other flow
obstructions.
Heater should fire on call for
heat. Re-verify that water flow
is above minimum require-
ment.
Minimum Flow Requirements
Model Flow
200 20 gal/min (76 LPM)
175 20 gal/min (76 LPM)
250 25 gal/min (95 LPM)
300 30 gal/min (114 LPM)
400 40 gal/min (151 LPM)
If water pressure is outside of
adjustment range that will
open switch with pump off
and close switch with pump
on, replace with flow switch
set above minimum flow
requirement
.
Model Flow
200 20 gal/min (76 LPM)
175 20 gal/min (76 LPM)
250 25 gal/min (95 LPM)
300 30 gal/min (114 LPM)
400 40 gal/min (151
LPM)
Is red “SERVICE
HEATER” LED
“on”
YES
YE
S
NO
YE
S
NO
NO
Is red “SERVICE SYSTEM”
LED
on?
Verify that pump is on, filter is
not blocked, and the water
flow is above the minimum
requirement
.
Check that water pressure is
within the adjustment range of
the Pressure Switch (0-5 psig
)
Verify that switch wiring is OK
and Pressure Switch port is
not blocked, and replace
water Pressure
Switch.
Check whether any of the
red diagnostic LED’s on back
of board (AGS, AFS, SFS,
HLS or PS) are
“on”
GO TO
“HEATER WILL NOT FIRE - C”
Page 40
Go to “Diagnostic LED’s”,
(Pages 42 and
43)
With pump running, adjust
Water Pressure Switch to
lower pressure until ‘SER-
VICE SYSTEM” LED goes
out. Then verify that “SER-
VICE SYSTEM” LED goes on
with pump of
f.
YES
YES
YES
NO
NO
NO
CONTINUE
Minimum Flow Requirements
Section 5. Troubleshooting
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