Troubleshooting a Hot Tub Thermostat

Over time, a hot tub thermostat may stop functioning correctly for a number of reasons. You can employ a few troubleshooting methods to replace worn or defective parts. Most of the issues will have a few possible causes and therefore a few possible solutions. There are a few tests and observations you can check to identify the problems you may be having with your hot tub thermostat. Keep in mind that electrical repair is potentially dangerous around water. It is best that repairs be done by a spa technician or qualified electrician. No matter who does the work, be sure that the power is cut off or disconnected before you begin.

Check the Heater Element and Assembly

The coil element in a hot tub is located in a housing heater assembly. The heat which is produced by the coil element is exchanged to the water while it flows through the tube. This assembly incorporates the thermostat and high limit hot tub switch. Heater assemblies take on many forms. No heat can mean that the heating coil is burned out which causes the thermostat and switches to not work properly. Low heat or reduced heat is caused by a water flow reduction as opposed to the heater’s electrical problem. Check the filter to ensure there is no clogging and obstructions restricting the water flow of the spa. Excessive buildup can reduce the efficiency of the heating element.

Test the Heating Element

Remove the heating element from the circuit. To do this, disconnect both the power leads of the heat terminals and take the measurements with a meter (ohm meter). The ohm meter should be on its lowest setting. Resistance is to be measured between these two terminals with the meter's test leads. The range should read between 9 and 12 ohms. If the reading is low, the bad unit is short circuited. If the reading is too high, the bad unit is a result of limited conductivity or open circuit.

Test Other Heater Components

If after the above testing and the results turn out to be okay, the problem may be caused by the thermostat or light switch. Check these by disconnecting the wires to the light switch and thermostat. Check for continuity. If the high switch limit is tripped, the light switch has no continuity. Press the reset button to test again. The meter should show continuity when the thermostat is turned clockwise fully. An open circuit with no continuity should be shown when turned counter clockwise.

A Few Things to Remember

When installing heat elements, be careful not to twist or bend the electric terminal. Prevent air from remaining in the plumbing since dead air can cause overheating. Keep the water balanced in the hot tub to prevent heater parts from being corroded by acidic water. Sanitizer is to be maintained in the hot tub to prevent bacteria. Bacteria can eat heater sheath away. Turning heater off and on continuously throughout the day puts a strain on your heating element. If you have a control system that operates on a timer, it will prolong your heater life.