Thermistor; Water Pressure Switch - Hayward H200FD Service & Installation Manual

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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:
switch or flow 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.
Do not operate the pool heater without the function of a properly adjusted pressure
USE ONLY HAYWARD GENUINE REPLACEMENT PARTS
Pomona, CA Clemmons, NC Nashville, TN
Tel: 908-351-5400 www.haywardpool.com