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Thinking of buying a heat pump for your pool? Before you part with a penny, here’s what you need to know, and what most pool companies won’t tell you.

By Tim Bareham, Cresta Leisure, Portland Pool Products dealer in Dorchester, Dorset.

We have been extremely successful in selling Portland Pool Products heat pumps here at Cresta Leisure because we adopt a totally different approach. However, it’s the correct approach both in terms of the laws of physics, and, more importantly, in terms of delivering our customers the best performance, value for money and minimal running costs.

First things first, a bit of secondary school physics. Heating a pool is exactly the same as boiling a kettle, i.e. the more water you put in it, the longer it takes. You can speed things up by using a more powerful kettle. Therefore a 3kW kettle will boil the water more quickly than a 2kW kettle. However, the key point here is that the amount of electricity you will use to boil the same amount of water will be exactly the same, it will just take longer with a 2kW kettle than it will with a 3kW.

Now, outside influences which cause heat losses in swimming pools, such as moving underground water or a cold wind across the surface, have a major influence on the sizing of a heater but they are the exactly same conditions whether you are using gas, oil, direct electrical heaters or heat pumps. To try and compare actual running costs is nigh on impossible as people pay different tariffs for different fuels all over the country.

The most important thing when buying any kind of pool heating system is to buy the biggest one you can afford and which can run off the available supply. This is because the difference in selling price between a 10kW heat pump and a 15kW unit is NOT 50% more in price, but it IS 50% more in output.

The Portland Pool Products heat pump leaflet and web page gives the coefficient of performance (COP) graph for their range of heat pumps, which is the single most important piece of information to consider when choosing a heat pump. There is not another heat pump manufacturer that will publish this graph because they cannot offer the same COP at the lower ambient temperatures that a Portland heat pump can, and which, crucially, we routinely experience here in the UK. Indeed, many say that they do not have a COP greater than 1:1 below 15°C!

The Cresta Leisure policy on heat pumps is to establish the available power supply close to the required position of installation, then advise the client to install the biggest heat pump that can run off that supply. REGARDLESS of the size of pool, a pool company should always sell the biggest heat pump the customer can afford and has the supply to run it in order to get the maximum performance level, value for money, and best running costs.

Unfortunately, most pool companies don’t do this. They will be scared of losing a sale to someone they fear might be price conditioned, and sell them the smallest and cheapest one they think they can get away with. Invariably, this leads to customer dissatisfaction as the unit will not be able to keep up with the demand on it, except for on the very hottest days our summers have to offer, by which time of course, the customer’s money is already in the bank.

Unfortunately nearly all heat pumps look the same (i.e. a big box with a big fan in it), and some unscrupulous companies use this to their advantage because they will tell potential customers that all heat pumps, therefore, are the same, so “buy ours because we’re £1,000 cheaper than the company down the road”. The best way to select and buy a heat pump is to UNDERSTAND the graph of average temperature loss in W/m2 (i.e. Watts per square metre of pool surface area) against ambient temperature, and have a large copy of the COP graph to hand to reference this against.

Finally, here at Cresta Leisure we offer an unconditional 100% money back guarantee if the customer is not totally satisfied (something that not one of our competitors is prepared to offer). Needless to say, we have yet to remove a single heat pump, nor give back a single penny in refund. Simply because with a Portland Pool Products heat pump we average around a 3:1 COP throughout a UK swimming season. In simple terms, this means a client gets three times more heating energy out of the heat pump than they pay for to run it. And, that’s an AVERAGE throughout an entire UK swimming season – not a peak output on just the very hottest days! There is not another manufacturer that can hold a candle to this kind of performance.