Steaming tub in front of mountains

A hot tub that doesn’t heat properly is understandably frustrating. Fortunately, issues with your spa heater are often easily fixed. Here we’ll discuss common problems and how to address them.

How Does the Heater Work?

The spa heater’s job is to warm the water in the hot tub. If the water temperature falls below the programmed temperature ranges, the hot tub turns the heater on automatically and starts circulating the water until the programmed temperature is reached.

The heater and pumps automatically switch on and off to maintain programmed temperature ranges. The hot tub itself is designed to preserve heat and keep the water warm (measuring temps every couple of minutes), and is not able to cool the water.

In order for the heater to work properly, it needs adequate water flow from the spa. Ensure the water level is at least one inch higher than the highest jets (excluding neck and shoulder massage jets) to avoid low-flow-related damage to the heater.

It is also important to complete the priming process any time the hot tub’s power is turned on. Priming removes air that may be trapped in the plumbing lines – air bubbles in the plumbing can cause serious damage. The heater is disabled during priming to prevent overheating.

5 Common Hot Tub Heater Problems

Many hot tub heater issues are signs of inappropriate levels of air/water in the spa or a problem with filtration. Often, the situation is easily remedied.

Spa Heater1. Heater/Spa Shuts Down

Certain heater-related conditions will cause the heater, or the entire spa, to shut down. Typically this is because too little water/too much air is running through the hot tub’s system.

If the heater shuts down but everything else runs normally, you should see a warning on your topside control. Persistent flow trouble is likely, and you should not enter the water.

Stay out of the water and power off the ground fault circuit interrupter (GFCI). Make sure:

  • Slice valves are locked in the open position.
  • Water level is adequate.
  • Filter, filter basket and suction drain cover are free of debris. Change the filter if it’s dirty.

If the entire spa shuts down, you should see a warning on your topside control. The problem is likely:

  • Low water or flow levels.
  • Air bubbles in the heater.
  • Inadequate water in the heater.
  • Overheating – the temperature at the heater chamber sensor is high or excessively high. Get out of the water.

Stay out of the water and turn off the GFCI if overheating is the issue. In all cases, check the water levels and address as needed. If water level is not the issue, follow these steps:

  • Make sure the slice valves are up and locked.
  • Remove any obstruction from the filter basket and suction covers. Change the filter if it’s dirty.
  • Press any button to reset, or turn the power on if overheating was the issue.

If none of these fixes work for the heater or spa shutdown, contact your manufacturer for assistance and possible repair.

Be aware that continuous filtration can lead to overheating. Running filtration cycles only twice in a 24-hour period is recommended.

2. Water Leaking in the Heater Area

If you see your hot tub leaking, one place to check is in the spa cabinet. Plumbing unions are often the culprit, and they can loosen near the pump or heater.

Never over-tighten or use tools on the unions – simply tighten with your hand. If the leaking continues, turn off the GFCI and contact the manufacturer for assistance. A part of the heater may need to be replaced.

3. Heater Runs Too Often, Water Heats Improperly

If you notice the heater running more frequently, but the water is failing to heat normally or evenly, check the filter. It may be in need of cleaning or replacing.

4. No or Low Heat

If you’re not getting enough or any heat, the following problems and solutions might apply:

  • Spa is in economy or sleep mode, and only heats during filtration. Change the operating mode.
  • Thermostat is turned down. Increase the temperature setting to a desired level.
  • Temperature setting is off. Look for the illuminated heater icon on the LED display.
  • Breaker is off. Reset the GFCI and main breaker.
  • The filter is dirty. Clean or change it as needed.
  • Pump is air locked or slice valves are closed. Unlock air in pump and open slice valves.
  • Improper line voltage. Speak to an electrician rather than attempt to fix yourself.

Spa cover has shifted. Reposition the cover to be sure it’s fully covering the tub.

5. Overheat Message on the LED Display

It is best to get out of the hot tub if you see signs of overheating. A couple of things can trip the overheat warning.

Continuous filtration can lead to overheating, as can filtering to often or too much at one time. It’s recommended to let filtration run every 12 hours. Reduce filtration frequency and duration to avoid overheating.

High outdoor temperatures can make it difficult for your hot tub to cool down, triggering the overheat warning. Try removing the cover temporarily or adding cold water according to the filling instructions.

In most cases, heater issues are quickly resolved by changing settings or water levels. It might be as easy as moving the spa cover. If you are still having trouble, contact your Aqua Living dealer for assistance.