Heat pump sizing guide

Our heat pump sizing guide shows what we refer to as the ‘ideal’ capacity to achieve your target temperature consistently, this ‘ideal’ capacity is calculated to allow for lower temperatures at the start and end of a swimming season and for cooler spells that naturally occur all year round given the UK weather.

When calculating our ideal capacity we consider several factors including whether it is an above ground or in-ground pool, the amount of insulation, whether the pool is covered when not in use, the expected swimming season, average air temperature and of course the target water temperature.

It is important to remember that the heating capacity required to achieve a water temperature of 28 degrees will vary according to changes in air temperature and the increased heat loss that occurs at cooler air temperatures or due to lack or insulation.

Whilst we assume an average air temperature of 15 degrees, our calculations actually factor in the reality that it could be 10 degrees one day and 20 degrees the next, therefore it should be remembered that capacities you see recommended elsewhere are probably based on consistent air temperature and therefore may appear less than our ideal capacities.

Pool assumptions:

Pools are outdoors and covered with suitable solar or bubble cover when not in use

May to September swimming season

Pool water temperature for swimming is 27-28°C

Average air temperature is 15°C

Pond assumptions:

Ponds are outdoors and insulated and covered

Pond holding temperature 15°C in Winter / Summer 20-22°C

Oversizing:

To reach a higher water temperature a larger heat pump is recommended – approximately 2KW additional heating capacity for each degree above 27-28°C.

To extend the swimming season a larger heat pump is recommended – approximately 3KW additional heating capacity for each month before or after May to September.

Insulation:

Above ground pools with a cover but no additional insulation are classed as ‘uninsulated’.

In-ground pools with a cover, above ground pools that have been partially sunk into the ground or above ground pools with cover and additional side/base insulation are classed as ‘insulated’.

Sizing guide