SECTION FOUR – Routine Maintenance and Professional Servicing
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1. When the pool or spa heater keypad control is
“ON”, the LED readout displays the current
pool/spa water temperature as determined by the
Thermistor mounted in the water inlet header. This
water temperature is compared to the user-preset
desired temperature, and when the sensed water
temperature drops below the pre-set temperature,
the digital processor calls for heat.
2. Upon a call for heat, the K1 relay on the operating
control closes, supplying 24VAC to pin 1 to J2.
Current then flows sequentially through the Water
Pressure switch (PS), back through pin 2 of J2 and
out through pin 3 of J2 through the high limit
switch (HLS), back through pin 4 of J2 and out
through pin 5 of J2 through the spare switch
jumper, back through pin 6 of J2, and on to pin 7 of
J2 and pin 3 of J1.
3. Pin 3 of J1 supplies power to the IND terminal of
the burner control, which switches the internal
F1/F2 relay to supply 120 VAC power to the com-
bustion air blower. Pin 7 of J2 supplies power to the
air flow switch (AFS), which, after it senses the
pressure differential created by the combustion air
flow, closes and supplies power to pin 8 of J2.
4. 24VAC current flows from pin 8 of J2 to pin 4 of J1,
to the TH terminal of the burner controller. This ini-
tiates a 20-second heating cycle of the hot surface
igniter (HSI). After approximately 20 seconds, when
the HSI has reached operating temperature, the
VAL terminal of the burner controller is energized,
and 24VAC is supplied to pin 5 of J1, and out
through pin 1 of J3, through the AGS switch to pin 2
of J3, out through pin 3 of J3, through the Stack Flue
Switch (ES2) safety switch jumper to pin 4 of J3, and
out through pin 5 of J3 to the gas control, thereby
opening the Combustion Gas Control Valve.
5. If any of the PS, HLS, AFS, or ES2 open during the
call for heat, the 24VAC is interrupted from the IND
and TH terminals, which interrupt power to the
blower and gas control. The ignition sequence will
resume from the start when the open switch recloses.
6. If the AGS opens during a call for heat, the 24VAC
to the gas valve is interrupted, closing the gas valve
(or preventing it from opening). The operating con-
trol also goes into a lockout state, which requires
power to the heater to be turned off and then
turned on for the control to resume functioning.
NNNNOOOOTTTTEEEE:::: If, while there is line voltage connected to the
heater, you touch either line voltage terminal with
any 24VAC wire that is connected to the control
board (including the Fireman’s Switch jumper), you
will immediately destroy the control board and void
the warranty.
4-30
CR21
Plug 6-pin
connector
in here
Control Board
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Chance of electrical shock or fire.
The
control board uses 24VAC electricity. Be sure you take
all normal precautions for the voltage involved.
