How to Cut Hot Tub and Swimspa Running Costs.

How to Cut Hot Tub and Swimspa Running Costs.

How to cut Hot Tub and Swimspa running costs.

Heat Pumps

Air Source Heat Pumps for Hot Tubs and Swimspas are one of the most efficient methods of heating systems available and can save up to 80% in heating cost.

With the world-wide increase in energy prices, hot tub users are looking at ways in which they can reduce the cost of heating and running their spa. An Air Source Heat Pumps are a perfect way of achieving this. They include the following benefits;

  • Save money on energy bills
  • Low carbon footprint
  • Will work even in lower air temperatures
  • High Coefficient of Performance (COP)
  • Can be used for both heating and cooling
  • Easy installation
  • Minimal maintenance
  • Long working life


There is very little point in investing in a heat pump, to reduce running cost if your hot tub or swimspa is not well insulated. The most important areas to consider are;

Insulation safety/cover – If, over time, your insulation cover has grown heavy by compared to when it was new, there is a good chance the insulation has become water logged and its ability to insulate is dramatically reduced. Most hot tub covers are made of expanded polystyrene, this has air bubbles that are good for stopping heat transfer, but they can also collect moisture eventually making it ineffective as an insulator. A low-cost secondary floating cover, below the rigid cover, this will also improve to the heat retention

Cabinet and shell insulation – most spas and swimspas are built with a good level of internal insulation, but the manufacturers have to make their product competitive in, what is often a price driven market so, as a result insulation can often be improved. We offer insulation upgrades to all makes of spas and swimspas for more information please follow the links below.

Base insulation – To insulate the spa base can is a further way of reducing heat loss, some spas and swimspas do have base insulation but many do not. Where possible insulation can be added in sheet form of below the spa or swimspa or alternatively we can install within the cabinet. This all helps to make your leisure and health-giving hot tub more cost efficient and affordable.

Fact - replacing your old heavy insulation cover and improving cabinet insulation will save on running costs.

Can I add an Air Source Heat Pump to my Hot Tub or Swimspa?

Yes, you can add an air source heat pump to your existing hot tub. But there are a few things that you will need to consider first. Below we have provided more information on how to add an air source heat pump to your existing hot tub or swimspa.

What size Air Source Heat Pump (ASHP) do I need?

It is important to select the right size heat pump for your hot tub or swimspa, key factors will depend on volume of water, amount of use (part or all year), water flow rate and cost. Here are a few helpful tips. Most hot tubs and swimspas will have a 3kW heater as standard fit so, as a minimum don’t use less that a 3kW. It is a good idea to select a larger rating unit that fits into your budget.

With a hot tub of up to say 6 people with regular daily use of and the cover is replaced after use then a 4kW should be fine. Extended use or when not always replacing the cover then select a larger unit, say 6kW.

With a swimspa, even though it is probably fitted with a 3kW heater, we would recommend you consider at least a 6kW unit.

The bigger the heat pump the quicker the unit will heat the water but, it is important to ensure that here is adequate water flow through the heat pump! Your hot tub or swimspa will have either a 2-speed circulation/booster or separate circulation pump. Depending on the ASHP size and the distance a separate ‘shunt’ pump might be needed.

Our H&V team will be happy to assist call 01980 611555

Selecting the Location for your Air Source Heat Pump

You need to choose a location that will allow good air flow to the ASHP, you do not want it circulating its cold discharge air. You will also need to have plenty of space all around the unit, ideally 300mm of open space where the air enters and at least 2m where it exits. The unit cannot be in a box or shed, unless air flow is achieved.

It is important to consider the height of the heat pump in relation to the water level. It is always better to have the heat pump located at or below the water level, any higher than the water level is likely to need a larger or ‘shunt’ pump to push the water around the system.

When operating the heat pump will create a small amount of condensate water so it is good to run the to a small gravel soakaway or drain.

The ASHP extracts all of the heat from the ambient air and therefore the discharge air is very cold, do not site the unit so it blows over you or recreational space – it is excellent at keeping drinks cold!

Remember that you must keep the ASHP at least 1m from any neighbour boundary (3m in Wales).

How much pipe will I need?

You will need to measure the distance between the connection on the hot tub and final location of the ASHP, it is always a good idea to add extra to allow for the orientation of the ASHP.

It is good practice insulate the pipe runs, this will minimise heat loss from the pipe and reduce heating costs

What size pipe do I need?

Most Hot Tubs pipework is 2”, the heat pump will need to be plumbed on a bypass and not the full flow of the pump. Therefore, 1½” will often suffice, again we can advise with pipe selection.

How do I connect the Air Source Heat Pump to my hot tub or swimspa?

Firstly, you will need to identify the filter plumbing of your hot tub or swimspa. As mentioned above, you need to see if you have a 2-speed circulation pump or separate circulation pump.

The connection will need to be made after the pump and should be on a valved bypass so that the flow of water can be controlled and or isolated.

Most Catalina™ hot tubs and swimspas have pre-installed by pass, this is where the flow and return to the ASHP will be connected making sure that the flow into the ASHP is connected to the first connection after the pump and the return from the ASHP is the one after and down line. There should be a valve installed between the two connections to enable the flow of water to be increased or decreased to suit the flow requirements of the Heat Pump.

Depending on the hot tub or swimspa control system you might need to install a ‘change over’ switch, this will allow the existing control pack to manage the Heat Pump.

You will need a qualified electrical engineer to install a suitable power supply to the ASHP.

When all complete, enjoy the reduced heating cost your new ASHP will offer you.


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