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To replace switch:
1. Turn pump, gas supply and heater power off.
2. Open control panel door.
3. Remove wires, screws and tubing from the
switch.
4. Replace with new switch and reverse the above
procedures.
Water pressure switch:
The pressure switch (Figure 53) is preset at the
factory for deck level installations. When the heater is
located below the level of the spa or pool, the pres-
sure switch may require an adjustment to compen-
sate for the no-flow static head. The following proce-
dure is recommended when the switch needs adjust-
ment and/or is replaced:
1. Be sure the filter is clean before making the
adjustment.
2. With the pump and heater mode switch on, turn
the adjustment dial on the pressure switch clock
wise, until a click is heard from the gas valve.
3. Turn the adjustment dial counterclockwise
1
⁄4 turn.
4. Turn the pump off and on several times. The
heater should shut off immediately when pump is
shut off. If the heater fails to shut down with
pump, repeat the steps above until the switch is
adjusted properly.
CAUTION: Do not operate the pool heater without
the function of a properly adjusted pressure switch or
flow switch.
To replace pressure switch:
1. Turn pump, gas supply and heater power off.
2. Drain heat exchanger of all water.
3. Remove heater front door.
4. Remove wires from pressure switch.
5. Using two
1
⁄2” open end wrenches disconnect the
pressure switch from pressure switch tube.
6. Replace pressure switch and reverse above
procedures. Use new sealant on pressure switch
threads before re-installing.
7. Check for any possible leaks after start-up of unit.
Thermistor:
The thermistor monitors the return water temperature.
To replace thermistor:
1. Turn pump, gas supply and heater power off.
2. Drain heat exchanger of all water.
3. Remove side access panels.
4. Disconnect thermistor leads from circuit board.
5. Unscrew the thermistor from header.
6. Replace the thermistor and reverse above
procedures.
33
High limits:
The high limit is an automatically resetting safety
device wired in series with the thermostat, pressure
switch and main gas valve. See Figure 50. The pool
heater is equipped with two automatic high limits. The
limits are located on the heater header.
CAUTION: The two limit switches have different
temperature settings (check Parts List).
If the water temperature at the location of the limit
should exceed the limit set point, the main gas valve
will shut off gas supply to the burners.
An erratic high limit is often an indication of a prob
-
lem with water flow. Reduced flow may be caused by:
1. Clogged filter or strainer.
2. Excessive flow through the external bypass valve
if one is used.
3. Lime scale accumulation in the heat exchanger.
To replace high limits:
1. Turn pump, main gas valve and heater power off.
2. Drain heat exchanger of all water.
3. Remove side access panels.
4. Remove wires from high limits.
5. Unscrew the defective high limit.
6.
Replace the high limit and reverse above proce
dures.
Blower vacuum switch:
The blower vacuum switch will not allow the heater
to fire unless the combustion blower is operating.
32
IGNITOR
FLAME SENSE ROD
WATER PRESSURE SWITCH
CONTROL PANEL
GAS VALVE
TRANSFORMER
V
ENT PRESSURE SWITCH
B
LOWER VACUUM SWITCH
B
YPASS VALVE
(inside header)
FLOW CONTROL THERMOSTAT
(inside header)
DRAIN PLUG
(under header)
HIGH LIMITS
(on header)
THERMISTOR
(on header)
Control Locations
Figure 50
High Limit
Figure 51
Blower Vacuum Switch
Figure 52
P
ressure Switch
Figure 53
Thermistor
Figure 54