My hot tub won’t heat above 80 degrees

If your hot tub won’t heat, it may not necessarily be due to a bad heating element, but that is often the case.  In this article, we’ll take a quick look at the symptoms of a heater element failure.

The last thing anyone wants is a hot tub that stops heating during the winter.  We often get calls from customers experiencing partial heating.  Let’s take a quick look at how a hot tub heater works, and why your tub won’t heat all the way.

Most hot tub heaters consist of metal elements, which are shaped into coils or loops.  These elements are made of a highly resistive combination of metals.  The element is then coated with a non-metallic material that prevents electricity from getting into the water. 
The technology is exactly the same as an electric element in a toaster, electric stove or heating plate.   Since the element has such a high electrical resistance, much of the electricity going through the element is slowed down by the material the element is made of, which generates thermal energy, or heat.
The hot tub element is mounted in a tube that the tub pumps water through.  The moving water is heated by the element, which gradually raises the temperature of the total volume of water in the hot tub.

Electric elements typically fail in one of three ways:

1. The outer coating of the element cracks, allowing the electricity to get into the water, which creates a short that causes the hot tub to trip your circuit breaker.
2. The element gets coated by minerals in your water, or chemicals that you add to the water, building up the thickness of the element which inhibits the thermal energy from heating the water.
3. The metal element cracks internally, which shuts down the heating circuit. With no electricity flowing through the element, your hot tub won’t heat.

Failure number 1 happens without warning and prevents the tub from turning on.  The only solution is to replace the heater, although disconnecting the heater electrically will allow you to turn the hot tub on to circulate water.  Moving water is much less likely to freeze than stationary water, so with air temperatures in the 20’s and 30’s, that’s all that’s needed to be done to protect the hot tub until service can be performed. 
Failure number 2 happens gradually.  Over months, or even years, your tub will take longer to heat and may not even reach the desired temperature.  You may be aware of the pumps running more often then they used to as the spa computer tries to heat the water.

Failure number 3 happens without warning, but the tub will still run.  Without the heating element, the water will still heat due to the friction generated by the moving parts in your pumps.   Living in the northeast (NJ & surrounding states) , during the summer, you will only get your water to the low or mid 90’s.  In the winter, you’ll only get the water into the 60’s or 70’s.  In other parts of the country, your water temperature will depend upon your climate.

Another problem that will make it appear that your hot tub won’t heat is clogged filters.  However, when clogged filters are the problem, there are usually other symptoms, most often error messages such as FLO, FL, “—” or “###.”  Read more about those problems in this article.

For help with your hot tub heating or other problems, call Jersey Hot Tub Repair at 201-897-7900 or 732-894-4494.