Hot Tub Heater Troubleshoot

Spa heaters are usually the most problematic apparatus on your hot tub; the most phone calls service centers receive are regarding the hot tub heater. If you aren’t getting heat in your hot tub (which defeats the purpose of ownership altogether), you’ll want to quickly perform a hot tub heater troubleshoot to assess the problem and get your heater up and running again. If it’s winter where you are, you can face serious damage if your water cools and freezes in the tub, wreaking havoc on your plumbing.

WARNING: Working with an electrical appliance that is near water can be very dangerous. If you’re planning on touching or installing spa parts, DISCONNECT the power at the GFCI switch and/or main circuit breaker before continuing. If you don’t feel comfortable doing these sorts of repairs, JUST DON’T DO IT. You could end up costing yourself more money than you’ll save by undertaking the DIY job. Instead, call a qualified technician before proceeding.

Note: This only works if you have an electric heater

Here are the two main parts you should become familiar with. The heater assembly is meant to be immersed in water while staying operational. The spa heater elements housed inside the assembly can burn out very quickly if operated without cooling water surrounding it. They are also prone to developing scale or hard water buildup if you use a salt system to sanitize the water. This can cause limited heat output or can ultimately end in element failure. The spa heater assembly is typically housed in a stainless steel chamber with unions for easy removal.

The flo-thru heater element is housed inside of the heater assembly and needs replacing if it’s burned out.

Let’s go through a step-by-step process to help you remedy your hot tub heating woes.

Step One: Check for Power

You’ll first need to make sure your hot tub is getting power. You can check this simply by looking at the topside control panel to see if you’re getting any sort of feedback. If not, check the GFCI breaker, your hi-limit switch (which you can find by looking at your owner’s manual), and your home’s circuit breaker or fuse box.

IF the GFCI is tripped, there is a problem with your heater element.

IF your hi-limit switch is tripped on your heater, odds are you’re not getting adequate water flow and you should evaluate your water pump.

IF nothing is tripped and you still aren’t getting power, call a technician or electrician. IF you have power, continue to the second step.

IF your hi-limit switch is tripped on your heater or control box, it almost always means you’re not getting adequate water flow.

Step Two: Check for Error Codes

If you have power or have restored it to the unit and the water is still not heating, you need to move on to step two and see if the spa is working correctly. If you have a newer hot tub model, this can be simple to decipher because your topside control panel takes out the guess work. If you look at the panel and see the error code OH, your hot tub has overheated. If you see the error code FLO (another common one), there’s an issue with your water flow.

IF you get the FLO error, check your jets. If you don’t have water flow from the jets, the water can’t be heated. This could be a spa pump issue that needs resolution.

IF you hear the pump running smoothly but don’t have proper flow, chick your filter. It could be clogged or worn out, leading to hampered water flow. Low water levels will also lead to pump problems.

IF you get the OH code, the water is overheating. If it’s not an exterior problem (high outside temperatures during the summer), the problem could lie with the thermostat or hi-limit switch.

IF you have a digital control panel and have tried the above solutions and you still get an error code, turn off the power for one minute as a hard reset. If water flow resumes and the heat light is on the digital controls but you don’t have heat, continue on to step three.

Note: The water won’t heat immediately, so keep that in mind. It will take hours for cold spa water to show signs that it’s heating up. Give it at least 12 hours.

Step Three: Find the Assembly

For this, you’ll have to look into your hot tub cabinet to get a closer look at its inner workings. Locate the heater assembly that often looks like a metal tube housing that contains a heating element. The elements on and around it are the pressure switch, sensor probes, and some wiring. (Refer to your owner’s manual for a more accurate depiction of your hot tub’s parts.

Step Four: Look for Obvious Signs of Deterioration

A lot of times, you can tell what the problem is when you look at your heater assembly. Look at the terminals (the two elements that stick slightly out of the tubing) as well as the surrounding wiring.

If there is obvious rust or hard water deposits, the terminals look corroded, or the wires have blackened/become discolored, it’s typically necessary to replace the entire heating assembly instead of just the element. If there is none of these bad signs, you can replace the heater element.

Step Five: Replace the Element

• Remove the entire heater body from the control box.

• Remove the wires from the pressure switch and unscrew it so you can access the mounting nuts. There are usually two mounting nuts on the unit (sometimes more) on each end of the heater body.

• Remove the nuts from the element’s wire terminals, using a small wrench to hold the area below the terminals in place so that the entire unit doesn’t twist off. Keep this in mind during reinstallation.

• If your heating element has a sensor cover, remove the small nut and pop it off. Don’t be afraid to pull hard as they have a tendency to get stuck.

• Loosen the threaded end caps on both ends of the heater. This unit should be loose enough that it can be removed. Watch out for any extra wires that may be attached and remove those as well.

• Once out of the cabinet, remove the large nuts on top of the tube that keep the heater element in place.

• Once the nuts have been taken off, push gently on the terminals until they’re low enough to pull out the element.

• When you’re installing the new element (by basically reversing all of these steps, be EXTRA careful not to bend the terminals when inserting into the new housing. If you damage the terminals of the surrounding epoxy, your warranty will be violated.

• When reinstalling, know that the washers (if they came with the element) go on the OUTSIDE of the assembly while O-rings go INSIDE.

• DO NOT use lube or silicone on the seals.

• Tighten the large nuts on the outside of the assembly just enough to keep it in place. DO NOT over tighten.