Heater Will Not Fire - A - Pentair MT125 Installation And User Manual

Heater Will Not Fire - A

Start
Is POOL or SPA
displayed on the LCD?
YES
Check that correct 12-pin
plug is installed (red is
240V, black is 120V)
NO
If plug is not inst alled:
Install correct plug.
240V plug in 120V
circuit: Replace with
correct plug.
120V plug in 240V
circuit: Replace trans-
former, control board,
and ignition control
module (see "HEATER
WILL NOT FIRE-B
page 52.
Check fuse and all
other 24V components
for damage.
GO TO
"HEATER WILL NOT FIRE - B"
Page 52.
460906 Rev. D 8/2020
Press Pool/Spa button on
NO
pad. Does POOL or SPA
displays on LCD?
YES
Check for line voltage to
heater.
YES
Check for 24 VAC at
secondary of Transformer.
YES
Check for Line Voltage
between L1 and L2 terminals
on Terminal Board.
Check for Line Voltage at
Transformer primary pins.
White connects to Pin 3 on
Transformer, Black to Pin 2,
Orange to Pin 1.
240V: check Pin1 to Pin 3.
120V: check Pin 2 to Pin 3.
Jumper Fireman's Switch at
Terminal Board and depress
POOL/SPA On button on
membrane pad. Does "SPA" or
"POOL" display?.
Leaving jumper in place,
YES
check for 24 VAC between
Fireman's Switch terminals
and ground.
Remove jumper. Check ribbon
cable connection between
Membrane Pad and J6 on
Control Board. Depress
POOL/SPA On button is on
NO
again. Does "POOL" or "SPA"
display?
Jumper J6-6 and J6-3. Does
the mode toggle between
POOL and SPA?
YES
NO
NO
.
NO
NO
YES
NO
YES
YES
NO
NO
YES
YES
NO
MASTERTEMP 125 Pool and Spa Heater Installation and User's Guide
Section 3. Troubleshooting
Heater should fire on demand
for heat.
Restore power to heater.
Check wiring connections
between power supply and
Junction Box and between
Junction Box and Terminal
Board; restore continuity.
Check wiring connections
between Terminal Board and
Transformer primary and
restore continuity.
Replace Transformer.
Check Fireman's Switch circuit
connections (time clock, wiring,
external controller relay).
Remove jumper. Check wiring
between Transformer and J7
terminals on Control Board
and between J7 and
Fireman's Switch on Terminal
Board, check fuse, and
restore continuity.
Heater should fire on
demand for heat.
Replace Membrane Pad.
Replace Control Board.
51