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Hot Tub Not Heating

Hot Tub Not Heating?

Is your hot tub not heating? Presuming you have checked your filters are clean and there is no blockages (whoops ok go and do it now), this could be for a number of reasons. In this blog we focus on the element of the heater, so keep reading.

Hot tub heater elements are like elements used in household hot water kettles with a few important distinctions. Hot tub water chemistry tends to vary and it swings widely when having a party in your hot tub. Spa heater elements are also subject to issues from low water flow or air inside the heater and these variables can lead to a shorter heater element lifespan.

It is probably important at this point to distinguish which type of heater you have. So, sorry here is the technical bit.  Alternatively call Healthy Hot Tubs on 0333 7720082 to check which heater you have and skip to pumps.

Flow Through Heaters

A flow through heater normally requires a flow running through the heater of approximately 102.3 litres per minute to keep it cool. A typical hot tub pump provides this minimum flow. When flow is restricted below the 102.3 litres per minute, the element runs hotter than designed, and your spa heater element life is shortened. Flow through heaters come in many shapes like Tube, Tee and L-shape. Call Healthy Hot Tubs on 0333 7720082 for more information and to check which heater you have.

Hot Tub Not Heating Hot Tub Heater

Low Flow Heaters

Low flow heaters are designed for vertical mount operation. The exception is the tube or Laing spa heaters. You will see that these designs are made with a much longer element. These heaters and elements are made to operate on flows greater than approximately 41 litres per minute. Your low flow heaters should be paired with low flow circulation pumps like Waterways and Laing spa pumps. Low flow heaters normally cost more money.

Laing Heater


A main reason for your hot tub not heating could be a pump. Spa pumps are designed to flood fill and not to draw in air, sending it through the hot tub heater. The problems occur when the circulation pump, (pump supplying the flow for the heater) breaks. Unfortunately, not all hot tubs have sensors to indicate a low flow problem. Many early Chinese systems like the GD7005, GD 800 PCB’s and H30- R1 heaters, used on companys such as Danz Spas had no low flow warnings until the heater failed.

Air Bubbles And Air Pockets

As well as low water flow air bubbles or pockets can be a number one heater element breaker. Air that encounters the element, allows that element to rapidly heat unevenly in turn breaking the heater. Low flow heaters are mounted vertically, so the bubbles are constantly exiting the chamber. Tube heaters like the Laing heaters do not trap bubbles.


Ozone injectors on hot tubs should not be placed before the heater. Bubbles produced by the ozonator will as above, reduce the heater element lifespan and can confuse hot tub heater sensors.

Hot Tub Not Heating - Ozone Injector

Poor Chemical Usage

Poor hot tub water chemistry is damaging to heater elements, particularly low pH, Alkalinity and high hardness levels. As water becomes acidic or overly chlorinated, this can cause corrosion and in turn break the heater element. For information on chemical usage, talk to one of Healthy Hot Tubs Experts on 0333 7720082. Alternatively use our contact form to drop us an email with your questions.

Hard Water

Is your hot tub in a hard water area? or in a rural areas and your hot tub is filled from an onsite well? You can have trouble with metals and minerals. Lime & calcium can naturally collect on a heater element surface, forming scale. This layer of scale will slow heat transfer, resulting in lower efficiency, longer heater run time, and a higher internal element temperature. The scale build-up will not let heat escape and the element will essentially burn out. For information on how to deal with hard water or scale talk to one of Healthy Hot Tubs Experts on 0333 7720082. Alternatively use our contact form to drop us an email with your questions.

Hot Tub Not Heating

Need help with your hot tub not heating? Need an urgent hot tub repair? 

Call Our Hot Tub Service Team Today For More Information on 0333 7720082

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About Us

All Healthy Hot Tubs staff pride themselves on being true hot tub engineers we give all our customers our time. We believe in keeping your hot tub healthy.

The culture at Healthy Hot Tubs is customer needs first. We spend time diagnosing issues on repair jobs not just changing parts (only for them to break again). We also wouldn’t sell you a pump if a capacitor would do. Healthy Hot Tub engineers have the time to provide great service and excellent services. That is why all our customers, friends and colleagues recommend us. We are also the choice warranty engineers for many hot tub companies. Get great service at great prices. Call Healthy Hot Tubs today on 0333 7720082.

Live in Devon or Cornwall? Hot tub not heating? No problem. Healthy Hot Tubs work closely with South West Spas who offer the same great standards and values as ourselves. We will gladly pass you over to get your hot tub needs sorted in no time.