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All About Pool Heat Pumps

December 10, 2013 by Phil Nataghi

Many pool owners want to gain the health benefits of swimming but find that the season when the water is warm enough is too short. They may have considered a gas pool heater but been put off by the high running costs (particularly if you have to use propane). The answer is a pool heat pump. Although they are more expensive to buy they are cheap to operate and environmentally friendly. However they do have some disadvantages.

What Is A Heat Pump?
In essence a heat pump is a device which transfers heat from one place and deposits it elsewhere. In swimming pools heat is extracted from the surrounding air and transferred to the pool water. A heat pump can in addition be utilized to take heat from pipes sunk into the ground as is commonly the case when one is utilized for a home heating system. A drawback of air source heat pumps (as used for pools) is that they become less efficient in low temperatures and require a defrost feature to enable them to keep working.

Everyone is used to fridges and a/c units which work in the same way except they are used for cooling instead of heating. Whilst standard pool heat pumps are designed for pool warming all the ranges incorporate a version that can be reversed to cool the water.

How Do They Operate?
A heat pump comprises a circuit containing a refrigerant that includes two heat exchangers and an electrically  powered compressor that pumps the refrigerant round. In the evaporator the liquid refrigerant evaporates at low pressure taking heat from the air. The refrigerant, which is now a gas, is subsequently pumped round to the condenser at high pressure where it condenses releasing heat into the water. The refrigerant then returns to the evaporator to replicate the sequence.

Efficiency Of Pool Heat Pumps?
Whilst you are producing heat directly e.g. burning gas, you cannot generate more energy than you put in. Gas heaters are typically between 80% and 90% efficient. The key point about a heat pump is that actually produce heat so the heat energy generated is far larger that the electrical energy used. Therefore even though electricity is a expensive energy source a pool heat pump is nevertheless very much less expensive to operate than a gas pool heater.

Efficiency is declared as the COP (Coefficient Of Performance). This is a measure of how many units of heat energy are produced for every unit of electricity used. This value can vary however for domestic pool heat pumps something over five is an appropriate target. One thing to watch out for though, the COP varies depending on the air and pool water temperature and humidity. Although there is no set standard most manufacturers use 80 degrees for air and water and 80% relative humidity.

Advantages Of Pool Heat Pumps
The major advantage is low running costs but also they are friendly to the environment and do not create any emissions.

Disadvantages Of Pool Heat Pumps
Heat pumps cost more to buy than gas heaters and have a lower heating capacity. Also their performance deteriorates as the air temperature goes down.

Is A Heat Pump The Answer For You?
If you want to extend the swimming season during which your pool is in use and the heater will be in use for long periods then a heat pump will be perfect. But if you only want to heat the pool occasionally a gas heater will be more cost effective and will heat the pool quicker.