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How Does a Heat Pump Work?

how does a heat pump work

Heat pumps are both old heating and cooling technology and one that is still evolving. Back in 1852 the first scientific principles behind heat pumps and artificial refrigeration were developed and from there inventors built on the concept. In the 1940s, heat pumps emerged as a popular home unit, providing cozy comfort and single system convenience. Ever since the heat pump has continued to increase in both popularity and efficiency. Let’s review how a heat pump “pumps heat” to both heat and cool.

What is a Heat Pump?

A heat pump is a system that transfers heat, moving it from one place to another. In the summer months, a heat pump moves heat from inside your home and dumps it outside while in the winter months it reverses this process. An air source heat pump has two parts – an indoor and an outdoor unit.

A typical heat pump system includes:

  • A compressor that moves refrigerant through the system
  • Condenser coil and evaporator coil that heats or cools the air
  • Reversing valve that changes the flow of the refrigerant 
  • Thermostatic expansion valves that regulate the flow of refrigerant 
  • Accumulator that adjusts as the seasons need
  • Refrigerant lines that connect the inside and outside components
  • Heat strips used for additional heat on cold days 
  • Air ducts that allow the hot or cold air to flow throughout the home
How Does a Heat Pump Work?

How Does a Heat Pump Work?

The story of heat pumps starts with refrigerants. Refrigerants come with a unique power – easy to manipulate – and low boiling points. A refrigerant is a fluid that can move quickly from a liquid to a vapor and back to a liquid again, over and over again. As it changes phases it absorbs and releases heat. 

Heat pumps take advantage of that. As a closed system, heat pumps can force refrigerants to absorb and release heat where they want it to be. As the heart of the system, the compressor maintains the flow of refrigerant between the indoor and outdoor condensing units. 

While in cooling mode during the summer, warm air from your home is pulled into the ductwork by a fan which is passed over the evaporator coils transferring the heat to the refrigerant which is cycled outside. The refrigerant dumps the heat outside and makes the return journey to do it again until your home is at the comfort level you want. While in heating mode during the winter, this process is reversed pulling heat from the ambient air outside into the home.

How Does a Heat Pump Save Energy?

Heat pumps use electricity instead of fuel. The popularity of alternative fuel systems like heat pumps has been on the rise over the last decade as system efficiency standards increase. One of the reasons it is so efficient is the basic principle on which it operates – heat transfer. 

Simply put, heat pumps work on the concept that it is more efficient to move heat than it is to create it. Heat naturally moves from high temperatures to areas where the temperature is lower. By using a small amount of electric energy, a heat pump system can reverse that process by moving heat from places that are relatively low temperature to higher temperature areas. 

What to Look for in a Heat Pump

In the United States, every heat pump sold has an EnergyGuide label that tells buyers the heat pump’s heating and cooling performance rating so you can compare it to other models. Look for Energy Star which means the heat pump has met strict energy efficiency guidelines. The seasonal energy efficiency ratio (SEER) for the cooling season and the heating season performance factor (HSPF) labels tell you the energy rating. The higher the SEER and HSPF the better the energy savings.

Additional reading: HVAC Efficiency Ratings Explained

Benefits of Heat Pumps

Heat pumps have quite a few advantages. Innovations over the years have continued to improve heat pumps for efficiency and comfort. Heat pumps are typically quieter than an air conditioning unit, making it easy to find an outside home for the compressor unit, even near bedrooms and patios. 

Lower Bills

One of the cons of heat pumps is their lower life expectancy. Because they are used year-round, the life expectancy of a heat pump is about 15 years, slightly less than a typical furnace and air conditioner. However, the heat pump makes up for this with lower bills. According to Energy.gov, an air source heat pump can provide about one-and-a-half to three times more heat energy than the energy it uses. 

Great for Moderate Weather Areas 

Heat pumps are excellent options for moderate weather areas, like the Pacific Northwest, where the winter temperatures rarely regularly fall below 30 degrees. The reason is moving heat from very cold areas to a warmer one takes more energy than moving between two moderate temperature areas. However, when temperatures do dip you will still be warm. Supplemental heat helps the heat pump produce enough warmth to keep your home comfortable.

Related: The Best Temperature to Set Your Thermostat to in Winter

Types of Heat Pumps

Air-source heat pumps

The most common type of heat pump is called an air source heat pump. Air source heat pumps blow air over refrigerant-filled coils that transfer heat either indoors or outdoors depending on the season. Air source heat pumps also come in a ductless heat pump system.

  • Uses a compressor and refrigerant installed in an outdoor unit on the exterior of the home to transfer or remove heat from interior of the home.
  • Can both heat and cool through a compressor and reversing valve that moves refrigerant in opposite directions depending on whether heat needs to be added or removed from the home.

Ground-source heat pumps

A ground source heat pump is also known as a geothermal heat pump or water source heat pump. Since the late 1940s, geothermal heat pumps use the constant heat from the earth instead of the outside air as a heat exchanger. Geothermal and water source heat pumps absorb heat from the ground or a body of water through a loop system that carries the refrigerant or water through underground pipes and are able to heat and cool homes.

  • Rather than using the outside air as the heat source and repository, ground-source heat pumps take heat from the ground in the winter or disperse heat to the ground in the summer.
  • Liquid-filled pipes buried underground absorb heat from the ground during the heating season and move excess heat to the ground during the cooling season. This method transfers heat from the source and delivers it to—or away from—the home.

What’s the Difference Between an AC and a Heat Pump?

Air conditioners have one great superpower – they bring lovely cool air to your home all summer long. While they work as a heat pump, moving heat from inside your home to outside, air conditioners are only good for one season. We have created an in-depth guide on deciding if an air conditioner or heat pump is better for you.

Because they only run seasonally, air conditioning units typically last 15 to 20 years and may be a better match if you already have a furnace. The advantage to heat pumps is that they are all-in-one units – both cooling and heating – which saves space and uses one fuel source.

Does a Heat Pump Cool as Well as an Air Conditioner?

There is very little difference between how a heat pump and an air conditioner cool provided you are comparing the same SEER ratings. Other factors to consider are the size of your home, windows, doors, and insulation, along with the orientation of your home to the sun. These are all things a Jacobs Heating & Air Conditioning expert can help evaluate. 

Heat Pump is a Great Option for Portland

Heat pumps work best in warm climates that have mild winters and that description fits Portland perfectly. With average low winter temperatures in the mid-30s, a heat pump is an efficient and effective HVAC system that both saves money on bills and gives you an all-in-one system that works year-round.

Learn more about our heat pump installation and repair services.

How Jacobs Can Help

Deciding what kind of HVAC system you want to live with for the next 15 to 20 years can feel daunting. Jacobs Heating & Air Conditioning experts are here to guide you through the process to help you pick the right system for your home. Consultants will help evaluate your home to ensure you have a long-lasting system that will keep you comfortable in all seasons. Avoid extra costs and fewer repairs by scheduling a tune-up for your existing system before issues arise. Our maintenance plans keep your system running like clockwork without any stress or hassle. No matter what you need we’re always just a phone call away. You are welcome to review our statement on COVID-19 and how we’re taking precautions to protect you, our team, and our communities.

About the Author

Amanda Jacobs portrait

Amanda Jacobs, Internal Project Manager

Amanda Jacobs is an Internal Projects Manager and 3rd generation member of Jacobs Heating & Air Conditioning. She received her MBA from Seattle University and has worked for a leading HVAC training and consulting firm. When not talking HVAC on the Jacobs Blog, you can find her on the golf course or whipping up her famous vegan chili.