Troubleshooting a hot tub that isn't heating
WARNING - This article is written for people needing some help troubleshooting or repairing their hot tub. If you do not have basic knowledge of electricity, do not work on your hot tub. Water and electricity do not mix and carry the risk of electrical shock. If you are not capable of performing a repair yourself, please contact a hot tub professional or licensed electrician. The wiring and equipment described in this article represent a typical spa pack. Your pack may vary significantly from the components described below. Again, if you are in doubt as to how to properly troubleshoot or repair your specific pack, please contact a local spa professional or licensed electrician. Use any of the information contained in this article at your own risk. Hot Tub Essentials will not be held liable for any injuries that may result from the troubleshooting or installation of any electrical components in your spa.
How to troubleshoot a hot tub that is not heating - This article is for a mechanical spa pack (not one that has an electronic circuit board)
Step 1) Is there voltage at the element? (Is the heat indicator light on?) If there is no voltage, proceed to step 2. If there is voltage, proceed to step 3.
Step 2) Check to see if the contactor is open. If it is closed, test the switches between the relay and the element on the primary side. i.e. the high limit switch
If the contactor was open, then manually close it and test for voltage at the element. If there is voltage at the element, then replace the contactor.
If there is still no voltage at the element, a control switch or circuit on the coil side is open. Test for voltage on the load side of each switch to determine an open circuit. Or, jump from line to coil to determine the side of fault. i.e. check the thermostat, pressure or flow switch, pump switches, blower switch and the top mounted spa side control.
Step 3) If you have voltage at the element, test the amperage draw at the element. If there is no amperage draw, replace the heater element.
If there is amperage draw, calculate the proper amperage draw using Ohms law:
Amps = Watts ÷ Volts
For example, if you have a 5500 Watt heater (5.5 kW) and your heater is wired to 220 Volts, then the formula should look like this:
Amps = 5500 ÷ 230 (your answer calculates to 24 Amps)
If the amperage draw from your test is not close to the proper amperage draw that you calculated, then replace the heater element.
If the amperage draw from your test is the proper amount, look for loose wires or intermittent switches which may cause your element to cycle on or off. i.e. the pressure switch.