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How Does A Heat Pump Work?

How Does A Heat Pump Work?

What is a heat pump?

Heat pumps offers an economical and efficient way to provide year-round climate control for your home. Yes, heat pumps provide warm air in the winter and cool air in the summer. Plus, some models even provide domestic hot water heating. But how does a heat pump work, exactly?

How does a heat pump work?

Technically and simply speaking, a heat pump transfers heat from one area to another. This exchange of heat cools your home in the summer and heats it in the winter. The best way to understand the process of how a heat pump works is to break down the different components and their function in the heating and cooling process:


This is the liquid or gaseous substance contained within the heat pump system. It circulates through the system, and switches between absorbing, transporting, and releasing heat throughout the system.

Reversing valve

This valve is what changes the heat pump between heating and cooling modes by controlling the direction of flow of the refrigerant within the system.


Heat transfer takes place in the coil of the system. It is made up of a single loop, or multiple loops of tubing, which may also include fins that help to increase the surface area available for heat exchange.


The evaporator is where cooling action takes place. In this coil the refrigerant absorbs any surrounding heat and is boiled until it becomes a low-temperature vapor. The refrigerant then passes from the reversing valve into the compressor. Along the way, any excess liquid that wasn’t turned into gas is collected in an accumulator -- though not every heat pump has an accumulator.


The refrigerant then travels along to the compressor, where the molecules of vaporized gas are squeezed together, or compressed, under high pressure. This compressing process causes the temperature of the refrigerant to increase.


When the refrigerant makes its way to the condenser coil, it gives its heat off to the surroundings and converts back into a liquid.

Expansion device

The expansion device lowers the pressure of the refrigerant that was created when it ran through the compressor. As a result, the temperature of the refrigerant drops and is converted into a low-temperature vapor and liquid mixture.


The plenum is the part of the heat pump system most people are likely familiar with, even if they never knew its technical name. This is a large air compartment located immediately above or around the heat exchanger, and forms part of the system which distributes the heated or cooled air throughout your home.


The fan is what ultimately distributes the warm or cool air throughout your home, blowing it through the ventilation system.

To summarize, a heat pump transfers heat from one area to another by circulating refrigerant through a system that evaporates, condenses, and compresses -- creating heat transfer in the process. It is a fully reversible system that can be used to heat or cool your home and makes an excellent primary or supplementary climate control system, depending on where you live.

Are there different types of heat pumps?

It is also important to note that there are different types of heat pumps, which work similarly but have their own unique systems.

  • Air-to-air heat pumps. These transfer air from one side of the unit to the other.
  • Air-to-water heat pumps. This technology is used in ductless mini-split heat pumps and ideal for homes that used hydronic (or radiant) heat distribution systems.
  • Ground-source heat pumps.  Also known as geothermal, earth-energy systems, or geoexchange. Ground-source heat pumps offer open or closed loop systems. The pumps utilize the ground or an underground body of water to heat and cool homes. Additionally, piping installation for closed loop systems remains underground. The system extracts or inserts heat into the surrounding ground as the refrigerant travels through the system. Open loop systems run piping into a body of water for extracting and inserting heat.

Still unsure about selecting the right heat pump system? Call a local and trusted HVAC professional. A qualified HVAC professional will answer your questions. Plus, quality techs always provide the best home HVAC system that meets your needs and budget.