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Air-Source Heat Pump

See also: Categories: Swimming Pool Equipment, Pool Heating, Terminology

Heat pumps offer very efficient heating, and because of their high coefficient of performance (COP), have very low operating costs.


An air-source heat pump refers to a heat pump that uses electricity to transfer heat from the air to the swimming pool water.


Due to their energy efficiency and low operating costs, air-source heat pumps are rapidly growing in popularity. Heat pumps use electricity to transfer heat from the air to the swimming pool. They are most effective in warmer climates and when used regularly. It has been found that air-source heat pumps greatly benefit consumers who live in climates where the average air temperature exceeds 60°F (15.5°C) and consumers who use their swimming pools year-round.

How Air-Source Heat Pumps Work

Air is drawn into the heat pump and over an evaporator coil, which contains a very cold liquid refrigerant, sometimes referred to as “Freon.” As air passes over the evaporator coil, the refrigerant heats to become warm Freon gas. The warm Freon gas passes through a compressor, which compresses it to a hot Freon gas. Inside the compressor, large amounts of pressure is placed on the warm Freon gas until it becomes hot Freon gas. Then, the hot Freon gas passes through a condenser, which is where the swimming pool water enters and exits the heat pump. The swimming pool water enters the condenser, washes over the condenser coil, heats, and exits the condenser. As the swimming pool water heats, the hot Freon gas cools and becomes a warm liquid. Then, the warm liquid passes through a metering device. Inside the metering device, pressure is reduced on the warm liquid until it once again becomes very cold.

Advantages of Heat Pumps

Because an air-source heat pump uses electricity to transfer heat, rather than to create heat, it is able to produce more energy than it uses. The efficiency of a swimming pool heater is measured by its coefficient of performance (COP). The COP of a heat pump usually measures between 5 and 6, which translates to an efficiency rating between 500% and 600%.

  • Very efficient heating: Coefficient of Performance (COP) measuring between 5 and 6
  • Very low operating costs: due to high Coefficient of Performance (COP) - typically costs between $50 and $150 per month to operate
  • Typical life span: 10 years
  • Very environmentally-friendly: only uses electricity to transfer energy and emits no pollution
  • Multiple use: Some air-source heat pumps can be used to both heat and cool your swimming pool

Disadvantages of Heat Pumps

An air-source heat pump works more efficiently in higher temperatures because it can easily draw heat from warmer air. In contrast, it works less efficiently in lower temperatures because there is less heat in colder air. In lower temperatures, an air-source heat pump, while using about the same electricity, absorbs less heat from the cooler air. In addition, an air-source heat pump is also at risk of developing ice when it operates at temperatures below 50°F (10°C). This is because the air is cooled by 10° to 18°F (5.56°to 10°C) when it travels through a heat pump. So, when air below 50°F (10°C) enters the unit, it can cool to below 32°F (0°C) and begin to freeze the condensate that forms on the evaporator. When too much condensate freezes on the evaporator coil, the heat pump can experience mechanical breakdowns.

  • Has high upfront costs
  • Offers slower heating than gas heaters; heats pool water slowly
  • Operates less efficiently in lower temperatures - dependent upon air temperature

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