Thermistor, Control Thermostat, Watkins No Fault Heater, Hot Spring, Tiger River and Limelight

Description

Replaces the obsolete 39530 and obsolete 39205
Newly designed and includes o-ring. This control thermistor is a safety device that measures the water temperature of your spa and communicates that temperature reading to the Motherboard. It simply screws into the Watkins No Fault Heater Housing (hand tight only) and then plugs directly onto the motherboard inside the IQ 2020 control box. (If your existing thermistor plugs into the outside of the spa’s control box see item 78970). Always replace thermistors in pairs (ie; 79005 & 79006 OR 78970 & 78969 ).

Note: If you have an older style heater, these thermistor sensors might be too long. Please see item 34-01395-K

*If your heater looks like one of these discontinued heaters below, use 34-01395-K:
Used 1997-2003	Used 1997-2003
Hot Spring only (No-Fault 6000)	Both Hot Spring & Tiger River (No-Fault 4000 & 6000)

ALWAYS REPLACE THE THERMISTORS IN PAIRS. If a new thermistor differs in temperature sensing more than five degrees from the old thermistor, the system will go into a “fault mode” and prevent the heater, jet pump(s) and light from operating. So again, when replacing a control thermostat thermistor always replace the high limit thermistor as well and vice versa.

Thermistor 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.

Click this chart to show the OHM range of the thermistor

View Diagrams & Part Compatibility