My Hot Tub Doesn’t Get Hot… Basic Spa Troubleshooting


If your hot tub is just warm or, worse yet, cold, you’re probably not happy. The whole point is to have a tub that’s hot – really hot – and when it’s not, you want to know why.

You can always feel free to call us to come take a look but if you’re one of those with a strong DIY streak, you may want to do some basic spa troubleshooting first before you call in a professional. Here are five common problems that may explain why your hot tub isn’t getting hot:

#1 Thermostat Problems

troubleshooting basic spa

Your thermostat may be the problem if your tub has no heat, not enough or way too much. Older spas will usually have a mechanical thermostat while newer spas use a solid state thermostat attached to a circuit board.

If you have a mechanical thermostat you’ll want to…

  • Check the bulb for corrosion – if it’s shot, you have to replace the whole thermostat.
  • Check to see if the switch is engaging – use an ohm meter and listen for a low clicking noise that signals that the switch is okay.
  • Check to see if it is out of adjustment – power off, remove it and you can try adjusting it with a small clockwise turn with an Allen wrench (but test carefully so it doesn’t get too high and burn you)!

If you have a digital system you’ll want to…

  • Call a professional – because they are controlled by switches and relays on a circuit board they are extremely difficult to troubleshoot

#2 Low Flow Problems

To work properly, a spa heater needs adequate water flow. Heater chambers typically have a pressure switch in the heater chamber that is intended to protect the heating unit. If it detects that the flow is too low to protect the heater, it triggers a shut-down of the electrical circuit that sends power to the heating unit. Once the water flow problem is corrected, you should get heat if this was your issue!

Here’s what to do to verify that this is your problem…

  • Take out your spa cartridge and clean the filter – low flow can often be caused by a dirty filter.
  • Other low flow causes can be broken valves, clogged jets, clogged pipes or a broken pump impeller.

#3 Heater Element Problems

Heater elements in hot tubs are much like elements on an electrical stove but they are made to operate while in water. They must be immersed in water so they don’t overheat and burn out.

Here are some steps to check and see if your element is an issue…

  • Check for scale buildup on the unit – this is common if you have hard water.
  • Check for a short in the coating on the heating element.
  • Check with an ohm-meter if you have a newer spa that has the heater element encased in a stainless tube – look for a short or open reading to indicate an issue.

#4 High Limit Switch Problems

The high limit is a switch that is there to make sure your spa doesn’t run amok and won’t shut off. There is a pre-set maximum heat limit that, when reached, will open the switch that will then cut off the power to the heater element.

Here’s how to evaluate if this can be the answer to your lack of heat…

  • Test the high limits with the power on with an ohm-meter – it should be between 9-12 ohms.
  • Check to see if it’s tripping shortly after you turn it on – if so, it can be a low flow issue.
  • Check to see if it’s tripping at the end of the cycle – if this happens frequently replace the high limit rather than making a potentially unsafe manual adjustment.

#5 Miscellaneous (and Mostly Minor) Problems

In addition to these four more potentially serious problems listed above, there are some minor issues that can be quicker fixes to address your heating issues.

Here are some other things to consider…

  • Check for burnt wires, loose wires or wires that may have been chewed or damaged – look for these throughout the system.
  • Check your ground fault circuit interrupter (GFCI) – it’s on the electrical outlet of your spa pack and has a red test button (like the ones you may have on your bathroom outlet). If the red button is popped out, just press it back in to reset.
  • Check your spa pack door – some spas have switches that close only when the interlock door is closed and engaged.
  • Check the fuses and breakers – both in the house and the spa to look for issues.

Contact Us for Expert Service and Repair of Your Hot Tub

If your hot tub is a not-so-hot tub, contact Black Pine Spas for assistance. If these troubleshooting helps didn’t solve your problem, your issue is too complex for you to take care of on your own or you just don’t want to deal with it, we can take care of it for you.

All of our master technicians are factory trained and certified and can work on any make, model or brand of hot tub.

We can troubleshoot and repair any spa – from the newest model to one that’s decades old, we can help with both parts and repair services. Contact us for a consultation at your convenience to solve your hot tub heating problem so you can be back in your spa and relaxing as soon as possible.

Call Black Pine Spas at 800-896-5405 or click here to use our web form to request a service call.


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