Hot Tub Troubleshooting: Heater Problems | DoItYourself.com
Simple Measures if the Hot Tub is not Heating. There are some simple things you could try if the hot tub does not heat the water. First of all, open and close the spa door on the spa cabinet, and see if it starts heating. If the hot tub is gas-powered, you should check if the pilot light turned off and turn it back on.