How Heat Pumps Work

In General...

Heat flows naturally from a higher to a lower temperature. AquaCal heat pumps, however, are able to force the heat flow in the other direction, using a relatively small amount of high quality drive energy (electricity). AquaCal heat pumps transfer heat from the air, to a swimming pool or spa application.

In order to transport heat from the heat pump to the pool water, external energy is needed to drive the heat pump. The total heat delivered by the heat pump is equal to the heat extracted from the air, plus the amount of drive energy supplied. Electrically-driven heat pumps from AquaCal typically supply 100 kWh of heat with just 20-40 kWh of electricity.

Because AquaCal heat pumps consume less primary energy than other heat pump systems, they are an important technology for reducing gas emissions that harm the environment.

Let's recap:

• An AquaCal heat pump does not create heat, it simply moves heat from one place to another
• The heat that an AquaCal heat pump works with comes from the outside air (or, with water source heat pumps, the heat source may be well water, rivers, lakes, ground loops, etc.)
• It is much less costly to move heat than to create new heat

More Specifically...

1. Outside air is drawn across a heat collector (called an evaporator);
2. The heat from the outside air is absorbed by liquid refrigerant contained within the evaporator, causing the liquid refrigerant to boil (or evaporate);
3. Heat-laden vapor refrigerant is drawn into a compressor, where its pressure is raised.  Raising the pressure of the refrigerant forces the refrigerant molecules closer together, raising the temperature of the refrigerant (refrigerant temperatures, at this point, may approach 135ºF);
4. The hot refrigerant vapor then passes through one side of a dual-circuit heat exchanger: one of the circuits contains the hot refrigerant, while pool or spa water passes through the other side passes pool or spa water.  While the refrigerant and water never actually touch, the HEAT from the refrigerant passes into the water;
5. As heat is removed from the refrigerant (passing into the water), and because the refrigerant remains under high pressure, the refrigerant molecules can again condense together...the result is the refrigerant returns to a liquid-state;
6. Liquid refrigerant is then fed through a refrigerant metering device into the evaporator, where the whole process starts over once again.  In reality, throughout the heat pump workings, and as long as the compressor is in operation, the actions described in numbers 2-5, above, are occurring concurrently.