Hot Tub or Swim Spa Not Heating? Common Causes
Is your hot tub running but the water staying cold, getting colder or different from the set point? Learn what to check safely and when to arrange a professional hot tub repair in the Northeast.
You lift the cover expecting hot water, but the temperature has dropped, not moved at all or is different to what the display states. A hot tub that appears to be not heating correctly can be frustrating, especially when the pumps and control system still appear to work. The cause is not always the heater itself: restricted water flow, air locks, closed jets, temperature sensors, incorrect panel settings or an electrical fault may stop the system from heating.
First, note what the hot tub or swim spa is telling you
Look at the temperature settings, heat LED and any message or fault code on the control panel. Has the equipment been filled or serviced recently? Are your filter cartridges adequately clean, did you fill the does water appear to be circulating normally? Has an electrical breaker tripped? These details can help an engineer narrow down the problem before visiting.
Check the owner’s manual for the meaning of a displayed code. You can also check that the cover is fitted properly and that the control system has not been set to an incorrect mode you did not intend to use. Avoid opening electrical compartments or bypassing a safety device to get the heater running.
Water flow can affect heating
Equipment relies on adequate circulation before the heater will operate. A blocked filter, low water level or any circulation problem may therefore cause a heating fault. Inspect the water level and the filter cartridges against manufacturers advice. Do not run the equipment without the filtration arrangements specified by its manufacturer.
If the problem presents itself immediately or soon after draining and refilling, tell the engineer. That timing can be a useful clue. Similarly, a recurring flow or dry warning deserves attention even if the tub sometimes reaches its target temperature.
When to book a repair
Arrange an engineer appointment if the cold or lukewarm water condition persists, fault messages return, circulation is weak, intermittent or non-existent, or even if the electrical supply repeatedly trips. Stop using equipment that shows signs of electrical damage, overheats or leaks near electrical components. An engineer can inspect the relevant pumps, sensors, controls and heater in the context of the complete system.
At Northumbria Hot Tubs Ltd we resolve issues related to heating, circulation, pumps, blowers, flow sensors, spa pack PCB’s, topside control panels, auxillary topsides, control systems, and of course, nuisance electrical trip faults . Read about our hot tub and swim spa repair service . If you are experiencing issues with your hot tub or swim spa, please get in touch with us at on our hot tub repair contact form or call us on 07971410167 with the make, model, fault codes and a short description of what happens when you start the tub.