Heat Pumps 101: What Are They and How Do They Work?

Does your current AC unit need to be replaced? Are you looking to upgrade your home with central air conditioning? If you answered yes to either of these questions, you should give some serious thought to installing a heat pump instead of a standard central air conditioner. If you’re unfamiliar with heat pumps, this article will tell you all you need to know about what they are and how they work so you can decide if a new heat pump is right for your home.

How Heat Pumps Provide Energy-Efficient Cooling and Heating

The thing that separates heat pumps from standard AC units is that they can also provide heating. Heat pumps can be either air-source or ground-source units. Ground-source units provide geothermal heating, and we’ll look at them in detail in the next section. 

An air-source heat pump is almost exactly like a standard AC unit, and you would really never be able to tell the difference between the two if they were sitting side by side. The one thing that sets the two apart is the reversing valve found in heat pumps, which is what enables them to heat as well as cool. 

During the hotter months, a heat pump functions just like an air conditioner. Both units use coolant to remove ambient heat from the air in a building, and they then move the heat and release it into the air outside with the help of a fan. The reason the process works is that heat energy always flows naturally out of high-temperature areas into any nearby areas that are at a lower temperature. 

In physics terms, the high-temperature area is known as a heat source, while the lower-temperature area is called a heat sink. In an air conditioning system, the warm air flowing through the system is the heat source, and the cold refrigerant coil is the heat sink. 

The cold refrigerant that flows inside the house constantly captures heat from the air so that it becomes warmer as it moves through the coil before flowing back outside. Once outside, the refrigerant moves through an expansion valve in the AC or heat pump. This process of expansion instantly makes the refrigerant extremely hot so that it is now at a higher temperature than the air outside. As a result, the heat is then released into the air as it is blown over the condenser coil. 

Alternatively, in the winter, this process is reversed, and cold refrigerant moves through the coil in the unit outside and captures latent heat from the air blowing over it. Then the refrigerant passes through the expansion valve, which makes it much hotter than the air inside. Once the refrigerant moves inside, the heat energy is released to make the air in the home warmer.

How Geothermal Ground-Source Heat Pumps Work

As the name suggests, ground-source heat pumps remove or release heat into the ground instead of the air. In this type of system, pipes are installed in the ground below the frost line, where the temperature remains consistent throughout the year. These pipes take the place of the coil in a standard heat pump, and the refrigerant flowing through them works to capture heat from the ground when heating and release heat into the soil when cooling. The inside part of a geothermal system is the same as with an air-source heat pump, and the refrigerant still flows through a standard coil that removes or adds heat to the air in the home. This type of system can provide forced-air heating like an air-source heat pump or furnace, but geothermal systems can also be used to provide radiant heating. 

A geothermal heating and cooling system does require a major investment and will be much more expensive to install than a standard HVAC system. Still, it can be well worth it if you can afford the expense, as geothermal heating and cooling is far more energy efficient and costs much less to operate. According to the US Department of Energy, a geothermal system will use around 44% less energy than cooling and heating with an air-source heat pump and more than 70% less energy than cooling with a traditional AC system. 

Comparing the Energy Efficiency of Air-Source Heat Pumps and Other HVAC Units

Other than a geothermal system, heating and cooling your home with an air-source heat pump will almost always be the most energy-efficient option. When it’s cooling, the energy efficiency of a heat pump is comparable to a standard AC unit since they both work the same way. However, an air-source heat pump will use two to three times less energy than a gas furnace, electric furnace, or electric baseboard heaters. 

The only real issue with heating a home with an air-source heat pump in colder climates is that you’ll always need a backup or auxiliary heating option. Since heat pumps work by transferring heat from the air outside inside, they can’t work if the outdoor temperature is too cold. Most cold-climate heat pumps can work in temperatures as low as -10 to -20 degrees Fahrenheit, but they’re not all that effective as the temperature drops and will struggle to keep your home comfortable in extremely cold temperatures. Nonetheless, they work fairly well in Pennsylvania and will still save you lots on your heating costs as you’ll typically be able to rely on a heat pump throughout most of the winter. 

You should be aware that a heat pump will need to run its defrost cycle every so often in the winter, and the unit won’t supply any heat during this cycle. Defrosting is necessary to thaw the unit and melt the ice that naturally freezes on the coil in cold weather, and this is accomplished by activating the reversing valve so that heated refrigerant flows through the unit. 

On cold days, you may need to turn to whatever auxiliary heating you have to prevent your home from quickly becoming cold when the heat pump is defrosting. If your home has a furnace, you can program your heating system so that the furnace runs when the heat pump defrosts or when it’s too cold for the heat pump to work effectively. Some heat pumps also have their own auxiliary heating in the form of electric resistance coils that will automatically switch on during these times, but these will use quite a bit more energy than when the heat pump is running normally. 

Contact The Professionals

Ready & Able Plumbing, Heating & Air is your go-to company for HVAC installation in the Harrisburg, PA area. We work with all types of heating and air conditioning systems, and we install, repair, and maintain heat pumps, furnaces, air conditioners, ductless mini-splits, boilers, and geothermal systems. We also provide residential plumbing services and are available 24/7 for any HVAC or plumbing emergencies. To learn more about how installing a heat pump in your home can benefit you, contact our team of experts today.

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