Why is my Hot Tub not staying hot?

You will lose a degree or two of temperature as soon as the hot tub cover has been removed, this is due to the heat outside being cooler than that of the hot tub, within a few minutes the spa will detect this and automatically start to heat back up to set temperature (the majority of spas have a fitted sensor within the spa which will detect the drop in temp and enable the heater to turn back on)

Other reasons could include any of the following:

  • faulty part like a failed heater
  • low speed/circulation pump
  • pressure switch or thermostat
  • mode setting – could be set on Economy or Sleep which will not maintain the temperature – set on Standard
  • or even simply that there is not enough water in the Hot Tub or jets closed.

However, if the spa heats up again after use, then your spa is using more heat than your heater can replace. If this is the case, you could fit a larger heater (if your power supply allows), or you could avoid using the blower, which takes a lot of heat out of your spa. Many spas also turn the heater off when the jet pumps run – there is normally a jumper on the control box to switch on full-time, but again it will take more power, and you must get an electrican to check whether you have the correct supply cable and fuse.