The main electrical element in a hot tub is the heater element and assembly, which is inside the hot tub’s cabinet. The assembly houses the element coil and a filament surrounded by compacted insulating powder. A sheath of incoloy protects the coil and filament by resisting heat and corrosion and preventing water from coming into contact with the coil. Some assemblies also have sensor components, such as a thermostat and a hot tub high limit switch.
Electricity travels through the coil to create the heat, which warms the water when it passes through the tube. If the element is not getting any electrical current, it won’t get hot.
Troubleshooting Hot Tub Electrical Issues
• If your water is cold, the heating coil could be burned out or broken. The terminals could also be damaged, or the thermostat and high limit switches might be malfunctioning. Heating coils can be damaged by a “dry fire,” which occurs when the heater is running but little or no water is flowing. This makes the coil and incoloy sheath so hot that they melt. If you examine the element, you can see the damage.
• If the water isn’t getting hot enough, the problem could be a faulty thermostat or high limit switch. The heating element could be corroded by a buildup of calcium scale, which makes it less efficient. Your water flow might also be restricted by a clogged filter.
• The heater problem may be the result of a short circuit in the ground fault circuit interrupter caused by water seeping into the sheath. If the sheath is corroded and has a hole in it, you’ll need a new heater.
You can test the heater element with an ohm meter. Disconnect both power leads and the power to the hot tub before inspecting, removing or testing the heater. The resistance between the two terminals should be in the 9 to 12 ohm range. If the level is below that, there is a short circuit. If the reading is higher, there is an open circuit.
If the heater tests properly, check the thermostat and high limit switch with the ohm meter. Disconnect their wires, and touch the ohm meter’s leads to the terminals of each unit. They’re both simple on/off switches, so you’re checking for continuity. If you find there is no continuity in one of the switches, press the reset button, and test it again.
If you choose to replace the heater, be very careful. Electricity and water are a dangerous combination. Don’t force the assembly into place. That could damage the epoxy seal and allow water to enter.