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Heat pumps are innovative, all-in-one solutions for both heating and cooling your home. If you are considering upgrading your HVAC system, understanding how they work can help you decide if a heat pump is right for you.
Heat Pumps Explained Simply
Heat pumps are electrically powered heating and cooling systems that efficiently transfer heat from one place to another. If you want to cool your home, a heat pump will transfer heat from your indoor air to outside. Conversely, during the winter, it will extract heat from the outdoor air and move it indoors.
The Main Parts of a Heat Pump
Knowing the roles of the various parts of a heat pump makes it easier to understand how it works.
The Refrigerant
Refrigerant plays a crucial role in a heat pump’s operation. It absorbs and releases heat by alternating between liquid and gaseous states without changing its chemical composition. This rapid phase change is what allows the heat pump to transfer heat efficiently.
Most modern heat pumps currently use R-410A refrigerant, a hydrofluorocarbon (HFC) that offers high energy efficiency and significantly less impact on the ozone layer than older refrigerants like R-22. However, due to environmental regulations, there will be a shift away from R-410A starting in January 2025. From this date forward, all newly manufactured heat pumps and residential HVAC systems in the U.S. must use lower global warming potential (GWP) refrigerants, such as R-32 or R-454B.
Evaporator and Condenser Coils
In a heat pump system, the evaporator and condenser coils can switch roles, depending on whether the system is set to heating or cooling mode. This flexibility distinguishes heat pumps from other HVAC systems, where evaporator coils are always located indoors and condenser coils outdoors.
When the heat pump is in cooling mode, the indoor coils function as evaporator coils. In this mode, the refrigerant flows into the indoor coils in a cold, liquid state. As warm indoor air from your home passes over these coils, the refrigerant absorbs the heat. This causes it to evaporate into a hot gas.
The outdoor coils act as condenser coils during cooling mode. The hot, gaseous refrigerant travels to the outdoor unit, where it releases the absorbed heat into the outside air and turns back into a liquid. This heat transfer works because heat naturally moves from areas of higher temperature to lower temperature.
In heating mode, the process is reversed. The outdoor coils become the evaporator coils, absorbing heat from the outside air, even in colder temperatures. The refrigerant, now carrying the absorbed heat in a gaseous state, moves indoors to the indoor coils, which function as condenser coils. Here, the refrigerant releases its heat into the indoor air, warming your home. After releasing heat, the refrigerant condenses back into a liquid and continues the cycle.
The dual functionality of the coils allows heat pumps to efficiently provide both heating and cooling by simply reversing the refrigerant flow.
The Compressor
The compressor plays a vital role in the heat pump’s heating mode by increasing the pressure of the refrigerant, which also raises its temperature. After the refrigerant absorbs heat from the outdoor air through the evaporator coils, it transitions into a warm, low-pressure gas. At this point, it flows into the compressor and is pressurized into a much hotter, high-pressure gas.
This step is essential because, in colder conditions, the refrigerant may not absorb enough heat to reach a high enough temperature for effective heating. By compressing the refrigerant, the heat pump ensures that it can transfer more heat into your home during the heating cycle. Once the refrigerant exits the compressor, it moves to the condenser coils, where it releases the accumulated heat to warm your living space.
The Reversing Valve
The reversing valve directs the flow of refrigerant. This component allows a heat pump to switch between heating and cooling modes by changing the direction of refrigerant flow in the system.
Fans and Motors
A heat pump relies on fans powered by electric motors to move air through the system. These fans are essential for drawing in air, passing it over the heated or cooled coils, and then circulating it back into your living space.
A heat pump typically has two fans. The first is the indoor fan, often called the blower fan, which is located within the indoor unit. This fan draws in air from inside your home, passes it over the evaporator or condenser coils, and then distributes the conditioned air back into your rooms.
The second fan is housed in the outdoor unit. It pulls in outdoor air and pushes it across the coils in the outdoor unit. In heating mode, this fan helps the refrigerant extract heat from the outdoor air. Conversely, it aids in expelling heat absorbed from your indoor air when in cooling mode.
Types of Heat Pumps
There are four common types of heat pumps used in residential homes. They include air-source, ground-source, water-source, and hybrid heat pump systems.
Air-source Heat Pumps
Air-source heat pumps use the outdoor air as the medium for heating and cooling. They can be ducted or operated as ductless mini splits. Ducted air-source heat pumps connect to your home’s central ductwork system and supply heated and cooled air via vents installed in every room. Ductless mini-split heat pumps do not use ducts. Instead, the outdoor unit is connected to indoor air handlers that are mounted in each room or space you want to heat and cool.
Ground-Source Heat Pumps
Ground-source heat pumps, also known as geothermal heat pumps, operate similarly to air-source heat pumps. However, they use the ground as the medium for heating and cooling. The earth maintains a consistent temperature of around 50 to 60 degrees Fahrenheit year-round, providing a reliable heat source and sink. The disadvantage of geothermal heat pumps is that they are expensive to install because they require underground piping.
Water-Source Heat Pumps
Water-source heat pumps absorb and release heat from nearby bodies of water such as ponds, rivers, or lakes. There are two types of water-source heat pumps: closed-loop and open-loop systems.
Closed-loop systems circulate refrigerant through pipes submerged in a water body. The refrigerant absorbs heat from the water or releases heat into it, depending on the mode. Open-loop systems, on the other hand, require two boreholes or wells. One is to draw water from, and the other is to return the water after heat extraction or release.
Hybrid Heat Pump Systems
Hybrid heat pumps are common in areas that experience extremely low temperatures during winter. When it’s freezing outside, an air-source heat pump can struggle to extract heat from the outdoor air. To solve this problem, homeowners add another heat source, such as a boiler or furnace. They use this supplemental heater during the coldest winter months and their more efficient heat pump the rest of the year.
Contact On Time Experts for More Information
At [company_name we have been serving the residents of Dallas, TX and the surrounding areas since 1981. We install, repair, and maintain heating and cooling systems, including heat pumps. We can also help with all your indoor air quality and plumbing needs. Contact us today to schedule an appointment with one of our talented team members.
