What is an Air Source Heat Pump for a Hot Tub or Swim Spa and why do you need one?

  • A good quality and well-known brand, Vian Power air source heat pumps are specifically designed to fit your hot tub or swim spa for low-cost hot tub heating. Compared to your existing hot tubs heater, they can be up-to 75% more efficient.

What are the advantages of having an Air Source Heat Pump fitted to my Hot Tub or Swim Spa?

  • The main advantage is saving money on your electricity bills, in addition, an air source heat pump will pay for itself over time, meaning that you will ultimately see a return on your investment.
  • An air source heat pump uses far less energy than your existing electric heater inside your hot tub, whilst still producing a higher output of heat.

How are Air Source Heat Pumps fitted to my Hot Tub or Swim Spa?

  • They will need to be fitted by an experienced hot tub technician as some plumbing and wiring is involved. All our pricing includes standard delivery and installation within our coverage area.
  • We have used our extensive knowledge and expertise to bring you the very latest in hot tub heat pumps for the UK. They have been extensively tested and we have great reviews on Checkatrade.
  • Starting from £1275 and ranging in size, they can fit to most hot tubs and swim spas.

The Smart Choice

If you are the proud owner of a hot tub or swim spa or are looking to purchase a new hot tub or swim spa then adding an air source heat pump is the smart choice.  Hot tub and Swim spa heat pumps are our best-selling accessories with hundreds of customers already benefiting from savings on their electricity costs.





  • Electrical requirements – The heat pump does not need any additional electrical installation on site as the unit will take its power from the hot tub or swim spa.
  • Planning – Each installation will vary, and we will undertake a site survey to review and discuss the best fitment and location for the heat pump. This survey is free of charge to our local clients and is a great opportunity to discuss the best option for the installation of the heat pump.
  • Fitment – We will undertake some basic modifications to your hot tub/swim spa to plumb the heat pump into the heating system. There will be an inlet and an outlet pipe plumbed into the hot tub base/cabinet to provide circulation through the heat pump.
  • Location – The heat pump requires a minimum of 450mm of inlet space and is recommended to have a minimum of 1500mm of space for the fan outlet.


  1. The fan in the air source heat pump draws air over a network of tubes that look a little like a car radiator. These tubes are filled with an eco-friendly R32 refrigerant.
  2.  The air then passes over the tubes warming up the refrigerant and turning it from a liquid into a gas.
  3. This gas is passed through a compressor which increases the pressure and significantly raises the temperature of the gas, which is then passed through a titanium heat exchanger.
  4. The hot tub’s water circulation system is plumbed through the air source heat pump and the heat from the gas travels through the heat exchanger, which in turn heats the water from the hot tub or swim spa as it passes over it.
  5. The refrigerant then cools and turns back into a liquid and starts the process all over again.

Due to how the system works, our air source heat pump will still produce heat even if the ambient air temperature is below zero as the compression of the refrigerant creates heat. Not only is this a far more cost-effective solution to heat your hot tub, it is also a much more eco-friendly option.




The chart below shows the kWh used by the heat pump to maintain the set point of 40°C. The test period is for 31 days between the 8th Dec 2022 and the 7th January 2023.

This was an ideal test period as the beginning of the test on the 8th Dec 2022 the UK experienced a very cold spell with temperatures dropping several degrees below zero.

Figure 1 shows the recorded temperature on the 10th of Dec 2022 of -3.1°C and the chart shows the kWh usage of 5.62kWh. Compared to figure 2 showing the temperature for the 4th of Jan 2023 being 11.5°C the kWh usage reduced to only 1.66 kWh.

The total kWh used by the heat pump over this period was 116.21 and this equates to an average of 3.75 kWh per day. As the ambient temperature rises, we can easily see that the efficiency of the heat pump increases significantly.

  • Test Location is Chichester, West Sussex, UK – All figures are just relating to the heating. – The hot tub is outdoors and not under a gazebo or shelter
  • The electric heater is disconnected so all heating is supplied by the heat pump only – We are testing a Vian 7kW S7 Plus Air Source Heat Pump
  • The heat pump is set to boost mode – The hot tub is a mid-specification model of approx 1550 litres of water. – The hot tub is set to heat to 40°C
  • We have used an older cover for these tests that is slightly waterlogged (to mimic real world) – The pipes to the heat pump are not insulated
  • The heat pump is within 1 metre of the hot tub (The hot tub has economy cycles set as follows: Tub goes into economy from 10.00pm to 10.00am, so does not heat for 12 hours overnight, 7 days per week. Then a second economy mode from 1.00pm to 4.00pm it also won’t heat)

To equate these kWh figures to a cost, we use the current price per kilowatt hour as a multiplier. Currently at the time of updating this case study the new kWh rate as per Ofgem is: 27.35 pence per kWh (1/10/2023)

10th December 2022, a cold day where we experienced temperatures below zero – kW usage = 5.62kWh used / Heating cost = £1.53

For comparison on the 4th January 2023 we had much a warmer temperature and the kW usage was only 1.66 equating to a cost of £0.45p.

The total average daily Kilowatts used during this winter test period of 31 days equated to 3.75 kW meaning the average daily cost of the heat pump was only £1.03p.




Looking at further long-term results we continued to measure the heat pump consumption through the winter, spring, and summer months. 

At the time of updating this case study we can report on a ten-month period of testing. This period covers the initial 31-day test period from 8th December 2022 up to the 7th September 2023. 

The chart and table below show the total kilowatts consumed by the hot tub air source heat pump by month during this period.


We can now look at a long period of results covering warm and cold months to determine an average overview of the consumption and cost experienced when using the Vian S7 air source heat pump to heat the hot tub.

The total kilowatts used by the air source heat pump over this period was: 749.55.

Resulting in an average monthly kW use and cost of 74.96 kW / £ 20.50.

Resulting in an average daily kW use and cost of 2.46 kW / £ 0.67p when we gross this data over a year and averaging by 365 days. 

Quite incredibly these figures mean that the total cost of the air source heat pump consumption over the ten months test period equates to £205.00 at a rate of 27.35 pence per kilowatt hour.

From 1st October 2023 new kWh rate will be set at 27.35p website reference (Ofcom)

These recordings and data are only for representative purposes as there are so many variables with different locations, temperatures and usage that could result in different figures. 

Whilst not independently vetted, we have performed this test to measure the kWh power consumption of our Vian 7kw S7 plus heat pump to show some of the real-world results. 

We used a simple inline kWh meter that connects to a smart home system to measure and record the usage.

We chose to undertake this testing during the colder months and incorporate a very cold period of weather to record the results in these conditions. As the ambient temperature increases through the seasons then the efficiency of the heat pumps will increase, and the kWh usage will reduce as can be seen with the longer-term testing results.

Our figures and recordings are only relating to the consumption of the air source heat pump. Whilst fitting an air source heat pump to your hot tub or Swim Spa will significantly reduce overall running costs it will only reduce costs pertaining to heating.  

We believe it is clear to see that a Vian Power Heat Pump is an extremely efficient heating solution for your hot tub or Swim Spa. 



Preparation & Planning

The start of your hot tub journey doesn’t have to be a confusing process. We’ve made it as simple as A, B, C.

Choosing Your Perfect Hot Tub, Upgrades and Accessories

There are many factors to consider when choosing the configuration of hot tub that is right for you and your family.

Purchase, Delivery & Installation

Whatever option you choose for the purchase, delivery & installation of your hot tub we have made the process as easy as possible.