After a long day, settling into the warm water of your hot tub sounds like an excellent idea. However, when the water moves beyond warm and comfortable to hot — it is a problem. Temperature fluctuations like this are a sign that something is wrong and can also be dangerous. It is essential to get to the bottom of the problem.
The thermostat is responsible for heating the water to whatever temperature you set. So, naturally, if the thermostat is not working properly, it may not register the temperature correctly. As such, the water may heat to a higher level than you desired. Thermostats fail for multiple reasons, but one of the more common issues is age, as it is not unusual for the thermostat in an older hot tub to start working incorrectly.
High-Limit Switch Malfunction
Hot tubs typically have some variant of a high-limit switch. In short, this feature is designed to ensure that the water does not exceed a certain temperature, and it works by forcing the heating element to turn off when the pre-set temperature is achieved. When the high-limit switch does not work, the water will continue to warm with no limit, which will cause the water to overheat. It could be that the switch was accidentally adjusted, but most often, the problem is that the switch is malfunctioning.
Faulty Heat Sensor
One feature that works hand-in-hand with the thermostat is the heat sensor. The thermostat gauges the temperature of the water, but it does so based on the readings from the sensor. If the sensor is not reading the temperature of the water accurately, it will also be unable to signal when the temperature of the water is too high. Often the sensor and the high-limit switch work off the same panel, so if the high-limit switch has failed, the same could be true for the sensor.
Clogged Water Filter
One element that helps keep the temperature of the water in the spa comfortable is the fact that the water is always in motion. When the water is stagnant, even if the thermostat or sensors are working efficiently, the water can overheat, as it is essentially being heated over and over. Clogged water filters prevent the water from flowing. To correct the problem, you should be able to clean or change the filter.
If you are experiencing unexplained changes in the water temperature of your hot tub, contact a hot tub repair professional as soon as possible to find out what is going on.