How Do Pool Heat Pumps Work?

A pool heat pump uses electricity and does not actually generate heat. Instead, heat pumps have a fan which draws in heat from the outside air that has been warmed by the sun. This warm air is extracted by a fan and circulated through an outer evaporator air coil.  Liquid refrigerant within the evaporator coil absorbs heat and transforms it into a gas. 

The warm gas in the coil then gets pumped into the compressor which increases the heat, creating a very hot gas that then passes through the heat exchanger condenser.

The pool pump circulates the swimming pool water drawn from the pool, it then passes through a filter and the heat pump water heater.

As the Liquid refrigerant gas and water from the pool is pumped through the heat exchanger at the same time, the hot gas transfers its heat to the water.  The water is heated 3-5 degrees as it passes through and then the warmer water flows back into the pool. 

The hot gas, as it flows through the condenser coil, returns to liquid form and back to the evaporator, where the whole process begins again.

Heat pump pool heaters work efficiently as long as the outside temperature remains above the 45–50ºF range.  The cooler the outside air they draw in, the more energy they use.  However, since most people use outdoor swimming pools during warm weather, this usually isn't an issue.

1 A unit of electrical energy (you pay for) runs the compressor which sucks evaporating Freon gas from the liquid filled evaporator tube. This causes a strong cooling effect (just like sweat evaporates from your skin and cools you off). The gas picks up four units of heat from the air flowing over the outside of the evaporator tubes.

2 The compressor squeezes this gas, causing its temperature to climb above 200° F (93° C) Result: Five units of heat added to the gas.

3 The hot, high pressure gas flows through the inside of the condenser coil. The colder 80° F (26° C) pool water picks up the five units of heat from the Freon which cools it down back to a warm liquid.

4 The warm liquid is forced through a valve. As it drops in pressure, it rapidly expands and becomes extremely cold liquid .This liquid flows back into the evaporator At 1 where it repeats the cycle.

Pool heat pumps are designed specifically for recreational water heating (in ground, on ground or above ground pools, spas, hot tubs, swim spas, etc.) If you have an air conditioner, dehumidifier, water cooler or a refrigerator, you already own a heat pump.

All these appliances use the same dependable technology to move heat from on place to another using electric power and a sealed refrigerant compression system.

Just like an air conditioner moves 2 to 3 units of heat from your home for every unit of electricity it consumes, heat pumps can use one unit of electric energy to move four (five or six for scroll models) units of heat from the air which delivers five to seven units of heat to your pool water.

The heat pump operates by taking the heat from the surrounding air and uses it to heat the water in your pool.

During heat pump operation, liquid Freon from inside the unit is pumped through the system (A) and is turned into a heated gas.

This happens when heat is taken from the surrounding air (B) as it is drawn through the evaporator by the fan.

The compressor (C) receives this warmer gas and compresses it to a higher pressure, resulting in the Freon reaching even higher temperatures.

As the unit sends the heated gas through the heat exchanger, the gas gives up its heat to the surrounding water (D).

The Freon is then reverted to its liquid state which completes the cycle (A).

The water (F), which is being forced through the heat exchanger (D) by your pool pump, is heated by three to five degrees as it passes through the heat exchanger. The water, now warmer, then flows back into your pool (G).