The Critical Components of a Heat Pump

Every HVAC unit has a variety of parts that make it work properly and that could fail as it ages. However, heat pumps are unique among these because they offer both heating and cooling for homes in John’s Island, SC. Discover the critical components that allow your heat pump to both heat and cool your home effectively.

Different Types of Heat Pumps

First, there are different types of heat pumps. This means that the components will vary slightly based on type. What we’ll focus on are the common air source heat pumps, which are similar to air conditioners.

However, heat pumps also include ground source and open or closed loop water-source models. When you hear about geothermal heat pumps it usually refers to one of these, being they use the ground or water for heat transfer.

Air-source heat pumps use a refrigerant that circulates to absorb heat. In the summer, it absorbs heat from inside your home and transfers it outside.

In the winter, it absorbs heat from the air outside and brings it inside. To make this work, a heat pump depends on these major components.


The compressor forces the refrigerant together in a smaller area, a process known as compression. When you force the same amount of a gas or fluid into a smaller area, it increases the pressure. Think about putting air in a tire and the pressure increase when you force more air into it.

When you compress the refrigerant and increase its pressure, it causes the refrigerant to warm up. The compression allows the refrigerant to transfer heat, allowing the unit to heat and cool your home.

Given the job that it does, the compressor is the component that consumes the most energy. If your compressor is experiencing an issue, you’ll start consuming more energy before it fails completely.

Expansion Valve

Opposite the compressor is the expansion valve, which allows the refrigerant to absorb heat. The expansion valve restricts the flow of refrigerant, allowing it to expand. Expanding refrigerant allows the temperature to drop, which then enables it to absorb heat.

A heat pump typically has a thermostatic expansion valve, which adjusts the flow of refrigerant into the coils. This allows the system to maintain ideal efficiency given the varying environment in which a heat pump runs.

Refrigerant Coils

In order to transfer heat, the refrigerant has to flow through coils that allow it to transfer heat. Your heat pump has two different coils, one inside and one outside. Air flows through the coil, allowing the refrigerant to either absorb heat from it or transfer heat to it.

Which coil is warm and which is cold depends on the mode in which you’re operating your heat pump. When it’s in cooling mode, the coil inside gets cold and the coil outside gets warm. In heating mode, the heat pump flips to make the coil outside cold and the coil inside warm.

Reversing Valve

The reversing valve is what allows the heat pump to change between heating and cooling modes. When you change the mode on your thermostat, it activates this valve, which reverses the flow of the refrigerant.

This doesn’t cause the refrigerant to flow differently through the compressor. Rather, once the refrigerant runs through the compressor, it changes the lines and coil where the high-pressure refrigerant flows. There’s a slide inside the valve that directs the compressed refrigerant to the appropriate line and coil.

Fans and Motors

Finally, your heat pump depends on its ability to circulate air. Heat pumps have two fans to move the air at the right places, which means two fan motors.

The circulating fan is the one inside. This draws air in from around your home, conditions it and then pushes it back into your home.

The outside unit contains the second fan. This draws air in from around your unit to either absorb heat from it or transfer heat to it.

There are many other parts that make a heat pump work that can fail. Our technicians have the expertise needed to keep your heat pump running throughout the year. Call to schedule an appointment for a new heat pump or to schedule a fall heat pump maintenance service.

Image provided by iStock

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