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Hot Tub Heater Troubleshooting

Heater Care Guide from Master Spa Parts

Heaters are an extremely essential part of your hot tub. So when it comes to making sure the heater is working correctly, this is at the top of the to-do list. Here are out some things to look for if your heater goes out.

How to Replace a Hot Tub Heater

  1. First, check and test your heating element. If your heating element is in good shape, it should be between 4.0 and 5.5kw. Additionally, it should draw at least 15-25 amps at 240v, and have 9-12 ohms of resistance. You can test your heater with any multi-meter and amp meter, or with an Ohm meter. Be sure to first take your heating elements out of circuit by disconnecting the leads from the heater terminals - this is the best and safest way to do the evaluation.
  2. Place the meter on ohms at 1000
  3. Put your test leads on each terminal. As stated above, it needs to measure between 9-12 ohms (if it does, its a good element, if not, that’s why you’re on this page, so keep reading.)
  4. Test for voltage by using the amp meter, and use those test leads to measure the amp draw.
  5. If there is an excessive amp draw, that means that the heating element is in fact bad. If there is no draw from the amp, that means no power is reaching the terminals. Remember, it should draw between 15-25 amps (15 amps for a spa thats wired for 110 volts, 25 amps on a spa that has been wired for 220v.)
  6. Then, test for a short to ground. Measure between one element terminal and the sheath of the element, on the meter’s highest ohm range setting. Any ohms that you get indicates that there is a short and bad element - you should always get an infinite reading on the meter.

Installing a New Element Yourself or Calling an Electrician

At this point, you’ve tested your heating element and indicated that you in fact need a new heater.

Our replacement heaters are located on our MSP heater product page. Two common replacement heaters are the 4.0kW Hot Tub Heater Element and the 5.5kW Balboa Heater with 12 Inch M7 Sensors as they work with a variety of select models of MSP hot tubs.

If this isn't your heater, take a look at our general Heater OEM replacement product page for other options - such as the You can either do this yourself or call an electrician. If you feel comfortable doing it yourself, we have put together a video that shows exactly how to replace a hot tub heater below.



Here are a few extra tips to keep in mind when it comes to your heater:
  • Be extra careful when it comes to installing any of the heater elements. It is really important that you don’t bend/twist the electrical terminal as it could lead to water getting inside it. Two wrenches are needed to do this properly.
  • Your spa chemical balance is extremely important when it comes to making sure your heating elements aren’t harmed or become exposed to corrosion due to the high acidity or scale build up in water. Make sure the spa chemistry is balanced and correct, using our chemical guide. This includes maintaining your sanitizer, because if not done, a metal dissolving bacteria can form. If this happens, all of your metal elements are in danger of corroding.
  • Be sure to avoid airlocks. Make sure all of the air is purged from the plumbing when filling up a spa or fixing equipment. If there is dead air in the heater it can cause overheating of the element (known as a dry fire). Here is how to un-airlock your pump.
  • Heater life can be prolonged if your hot tub’s control system allows for setting heat cycles by time of the day. Your element is subject to more strain when it’s turned on and off multiple times a day.