Watkins Hi-Limit Thermistor 38416

 HotSpring Tiger River Hi-Limit Thermistor 38416

Watkins PN 38416 Hi-Limit thermistor for HotSpring and Tiger River spas (see Model List Below). Used in conjunction with the 38415 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 38416:

HotSpring: Classic 1995-2000; 1995-2002 Grandee, Jetsetter, Prodigy, Sovereign; 2001-2002 Vanguard

Tiger River: 1995-2002 Khyber/Siberian, Manora / Bengal; 1997-2002 Sumatran; 1195-1996 Tondi

Note: newer model spas 2003-current use Hi-Limit Thermistor PN 39525

Related Item: Watkins No-Fault Titanium Heater:

PN 73790 -- OR -- 73791

Note: Symptom of this part failing is a flashing red "Power" light on the Hot Spring & Tiger River control panel or on the control box of the 1995-1996 Tiger Rivers. This thermistor is smaller in diameter than the Control Thermostat Thermistor 38415. 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.