Sensor is cutting out before the sauna heater is up to temperature
The first thing to check is your venting set up properly?
Without correct venting the sensor will get prematurely hot. See our venting FAQ
An easy way to test the sensor is to hang a cold cloth over the sensor just for experiment sake and see if it gets hotter. It usually does.
How to adjust sensor in the sauna?
Use a piece of wood holding the sensor to experiment with the best height for the sensor.
Two ways to adjust the sensor …
If you can pull out a little wire to lower it, do so. You can use a piece of trim with a channel cut into it (as shown below) to cover any exposed wire.
In the same way if the control is on the sauna wall you can drill a hole directly through the back of the control and lead a new sensor and wire through that and use the same piece of trim with channel to run that sensor to a height that works for your desired temperature.
This piece of trim can be made from a 1×2” and a table or skill saw to cut the channel. Run the trim from floor to ceiling, that way it looks good. Daddo’d out 1×2 trim for easy sensor replacement and adjustments. If the sensor has had water poured over it by users, it can go bad.
Some will build an additional wood cover that is opened at the bottom (this still allows hot air the surround the sensor so it works as designed) but keeps the water off the sensor. To test the sensor you can use a multimeter set to The OMS setting, place the multimeter probes into the small terminal strip on the thermostat where the sensor wires connect (this creates some resistance required), turn the heater on and if it works, that determines that the sensor is bad.
If the heater does not work through this process it is another component (most likely the thermostat). In a commercial setting where the bathers have access to the thermostat on the control, mistreatment of this can damage the potentiometer and cause random performance conditions. This requires that the thermostat be replaced.