Installation Guide

Pomona, CA Clemmons, NC Nashville, TN
Tel: [phone] www.haywardpool.com
USE ONLY HAYWARD GENUINE REPLACEMENT PARTS
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HIGH LIMIT SWITCHES:
The high limit is an automatically resetting safety device wired in series with the thermostat and gas
valve. See Figure 28. The heater is equipped with two automatic high limits, located on the water header.
If the water temperature exceeds the limit set point, the gas valve will be closed, shutting off gas supply to
the burners.
Erratic high limit operation is often an indication of a problem with water ow. Reduced ow may be caused by:
1. Clogged lter or strainer.
2. Excessive ow through the external bypass if one is used.
3. Lime scale accumulation in the heat exchanger.
TO REPLACE A HIGH LIMIT SWITCH:
1. Turn pump, gas supply, and heater power “OFF”.
2. Drain the heat exchanger of all water.
3. Unplug the high limit wires from the wiring harness.
4. Unscrew the high limit switch from the header.
5. Replace the high limit switch. Use new sealant on the high limit switch threads before reinstalling.
Reverse the above procedure to install the high limit switch.
THERMISTOR:
The thermistor monitors the return water temperature. See Figure 28. To replace the thermistor:
1. Turn pump, gas supply, and heater power “OFF”.
2. Drain the heat exchanger of all water.
3. Remove the front access panel. It is secured with (4) screws
4. Unplug the thermistor connector from the ignition control board.
5. From outside the heater, pull the thermistor leads out of the control box and through the hole in the
heater chassis.
6. Unscrew the thermistor from the inlet side of the header.
7. Replace the thermistor. Use new sealant on the thermistor threads before re-installing. Reverse steps
above to complete the procedure.
WATER PRESSURE SWITCH:
The water pressure switch (Figure 28) is preset at the factory for most typical, deck level installations.
When the heater is located above or below the level of the pool or spa, the pressure switch may require
adjustment to compensate for the change in static head pressure. If adjustment is needed, the procedure is
detailed in Section III, under Water Pressure Switch Test / Adjustment Procedure.
ATTENTION: Do not operate the pool heater without the function of a properly adjusted pressure
switch or ow switch.
To replace the pressure switch:
1. Turn pump, gas supply, and heater power “OFF”.
2. Unplug the high limit terminals from the main wire harness.
3. Remove the (4) screws securing metal trim panel around the header.
4. Remove the wires from the pressure switch.
5. Using two ½” open-end wrenches disconnect the pressure switch from the pressure switch tubing.
6. Replace the pressure switch. Use new sealant on the pressure switch threads before re-installing.
7. Reverse steps above to complete the procedure.