Heat Pump Series – What is a Heat Pump?

Arlington, TX – A heat pump is an appliance that captures thermal energy from an outside source. After collecting this thermal energy, it transports it to the thermal reservoir found within the heat pump. A heat pump moves this energy in the opposing direction of automatic heat transfer. It does so by consuming heat from a colder area and then releases it to a warmer area. Utilizing external power, the energy is sent from the source to the heat sink.

Common schematics for heat pumps typically involve four main components.  These components are the compressor, condenser, evaporator, and expansion valve. The medium that transfers the heat throughout these components is referred to as refrigerant.

Air conditioning systems and freezers are commonplace examples of heat pumps. However, heat pumps are a more generalized term and can apply to multiple heating, ventilating, and air conditioning (HVAC) appliances. Heat pumps typically will be used for heating or cooling. When it is used for heating, it uses the same mundane cycles that are utilized by air conditioners or refrigerators. However, it is done in the opposing direction, releasing heated air into the space instead of cold air.

How Does a Heat Pump Operate?

Look at a heat pump and consider it basically a refrigerator that has been turned inside out and increased in size.  Heat pumps deal with a much larger flow of energy and require pumps and / or fans. Refrigerators need only passive exchangers. A heat pump compresses refrigerant to make it warmer where it will be released to warm the conditioned area and then releases the pressure on the side where the heated air will be absorbed.

In other words, the refrigerant will be in a gaseous form while pressurized and transported through the heat pump by one of the main components called a compressor. On the opposite side, where it will be discharged, the now hot and pressurized gas will be cooled in one of the other main components called the condenser.  In the condenser the pressure will be lower, and the gaseous refrigerant will turn back into liquid.

After going through the condenser, it will then pass through the third main component called the expansion valve. Finally, after passing through the condenser the refrigerant moves to the final of the four main components called the evaporator.  In the evaporator it will absorb heat and then return to the compressor where the cycle will repeat itself over and over.


Randy Murphy

Randy Murphy has been building his knowledge of the air conditioning and heating business for several years now. He first started applying his knowledge while working for his father’s HVAC company. Later, in 1987, Randy started his own business: Metro Express Service. He has been a top 10 Trane & Amana dealer for over eight years. When it comes to heating and cooling, Randy knows the business better than anyone.
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