Hot Tub Not Heating But No Error Code? Here’s What to Check

If your hot tub isn’t heating up, but there’s no error code showing, it can be frustrating and confusing. Normally, spas display a fault message when something goes wrong. So when everything appears to be working, but the water just won’t heat, it’s not always clear what the issue is. The good news is that in many cases, it can be resolved with a few simple checks.

1. Check the Set Temperature

Start with the basics. Make sure the set temperature is higher than the current water temperature and the system is actually calling for heat. It’s surprisingly easy for settings to be changed accidentally, especially after cleaning, power cuts, or multiple users.

2. Check Your Heating Mode (Economy vs Standard)

Many hot tubs have energy-saving modes such as economy or sleep modes. In these settings, your hot tub may only heat during filter cycles, which can make it seem like it’s not heating at all. Switching back to standard mode often fixes the issue.

3. Inspect Water Flow and Circulation

Your heater relies on consistent water flow to operate safely. If flow is restricted, the system may prevent heating, even without showing an error code.

Check for:

• Dirty or clogged filters
• Closed or partially closed valves
• Airlocks in the system
• Weak jet pressure

A simple filter rinse can sometimes restore proper heating.

4. Reset the Hot Tub

Occasionally, your system may need a reset.

Try:

• Turning the power off at the mains
• Waiting a few minutes
• Turning it back on

This can clear minor faults and restart the heating cycle.

5. Check the Circulation Pump

If the circulation pump isn’t working correctly, water won’t pass through the heater.

Look out for:

• Little or no water movement
• Unusual noises
• Reduced flow from jets

Without proper circulation, the heater won’t activate.

6. Consider the Heater Element

If everything else appears normal, the issue could be with the heater itself.

A failing heater element may:

• Stop heating entirely
• Heat very slowly
• Show no visible error code

This usually requires professional testing to confirm.

7. Sensor or Control Issues

In some cases, the problem may lie with:

• Temperature sensors
• Control board components
• Internal wiring

These faults don’t always trigger error codes but can still affect heating performance.

When to Call a Professional

If you’ve worked through these checks and your hot tub still isn’t heating, it’s time to bring in an expert.

A professional technician can:

• Diagnose heater and pump issues
• Test electrical components safely
• Identify faults quickly and accurately

Our engineers are highly experienced and knowledgeable and can diagnose the issue and get everything running smoothly again, often within the same visit, so that you can get back to enjoying your hot tub. For more information, or to book a call out, contact us through our form, or give us a call on 023 9354 1154.