Watkins Hi-Limit Thermistor 2002-Current PN 39204 (Old PN 39525)

Watkins Hi-Limit Thermistor 2002-Current PN 39204 (Old PN 39525)

Watkins PN 39525 Hi-Limit thermistor for HotSpring and Tiger River spas (see Model List Below). Used in conjunction with the 39205 Control Stat Thermistor and the No-Fault Heater. 

Each spa is equipped with a high limit thermistor that is used as temperature sensor. The thermistor is a semiconductor that changes resistance with temperature changes (as the temperature goes up, the resistance goes down). The high limit thermistor trips if the water temperature exceeds 118 degrees F.

Spa Models Using Hi-Limit PN 39204:

HotSpring: 2002-current Vista, Grandee, Envoy, Aria, Vanguard, Sovereign, Jetsetter, Prodigy

Tiger River: 2002-current Bengal; Sumatran, Caspian

Limelight: 2008-Current Flair, Pulse, Glow

Note: older model spas 1996-2001/2002 use Hi-Limit Thermistor PN 38416


Related Item: Watkins 6kw No-Fault Heater

73790  -- OR -- 73791


Note: Symptom of this part failing is a flashing red "Power" light on the Hot Spring & Tiger River control panel. This thermistor is smaller in diameter than the Control Thermostat Thermistor 39530. It screws into the port (hand tight only) marked "Outlet" on the PDR replacement heater. Typically, when one thermistor needs replacing the other is close to failing as well and should be replaced at that same time. Thermistors have a reliable lifespan 6-8 years or so.

Test Procedure

1. Set the meter to 20K on the OHM scale.
2. Record the temperature of the spa water.
3. Unplug the thermistor from the control box.
4. Meter across the two Thermistor leads.
5. Refer to the Temperature versus Resistance chart below to find the correct resistance value for the temperature measured. If the temperature and resistance does not match that of the chart, this test has failed and the thermistor must be replaced. Remember if the spa has been inactive, the spa water temperature may be different
than the water temperature in the heater housing.



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If you DO NOT see an item that you NEED for your Watkins manufactured spa (HotSpring. Tiger River, Limelight, Solana, HotSpot) or Jacuzzi Hot Tub -- please EMAIL US! We may just have it and we can quote you a price: email us at: david@prescottspas.com

How to Find your Spa Serial Number?

Typically, your spa serial number decal will be inside the hot tub equipment compartment, attached to the spa shell wall. It will say the Manufacture Name (Watkins, or Jacuzzi), the Model Name, and then a Serial Number.  If you have any questions of how to locate the spa SN, or how to determine information of your spa by its SN, please email us.

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$22.50 USD