Definition of Heat Pump
A heat pump is an electrical device that takes heat from one location and moves it to another. A heat pump differs from a traditional heating and cooling system. Heat pumps do not create and distribute hot or cold air. Instead, heat pumps simply transfer air from one location to another. There are two major items in your home already that use heat pump technology: refrigerators and air conditioners.
There are two main types of heat pumps: air-source and ground-source. The most common air-source heat pumps (air-to-air) move heat into your home during the colder months and push heat out during the summer. Secondly, air-to-water heat pumps are not as common, but work in a similar fashion. These pumps use a hydronic distribution system to heat and cool. Additionally ground-source heat pumps use the earth or groundwater to heat and cool. These pumps are also known as geothermal, earth-energy, or geoexchange pumps.
How Heat Pumps Work
Heat pumps work by taking warm air and moving it to another location, thus cooling the desired area. Heat is transferred through a cycle of evaporation and condensation, during which a refrigerant substance is cycled through the system via a compressor pump. There are two heat exchanger coils in every heat pump, one of which evaporates the refrigerant and the other which condenses it. During the evaporation process the refrigerant absorbs heat from the surrounding area. Conversely, during the condensing process it releases heat previously absorbed. The movement between coils is what allows a heat pump to maintain a desired temperature.
Ground-source heat pumps can be open- or closed-loop systems, utilizing an underground body of water or in-ground heat respectively in order to heat or cool your home. Their refrigerants, compressors, and heat exchanger coils work in a similar manner as described above. They do however, require more installation consideration due to their unique design and space requirements.
Benefits of Heat Pumps
Year-round climate control is probably the biggest benefit of installing a heat pump in your home. Because the system is fully reversible, a heat pump can be used for both heating and cooling applications, allowing you to heat your home in the winter and dehumidify and cool it in the summer. Ground-source heat pumps offer the added bonus of being able to provide domestic hot water heating in addition to temperature control. This can help cut down on additional energy costs and also save floor space in your utility room.
Heat pumps are also highly efficient, making them an excellent choice for those looking to cut down on their monthly energy bills. In fact, it’s not uncommon to see a reduction in monthly heating costs of up to 50% when converting from an electric furnace to an all-electric air-source heat pump. Actual savings will vary widely depending on local climate, how old your current system is and electricity costs in your area.
Longevity is also another major benefit of heat pumps, with many units now lasting 15-20 years. The quality of the compressor and amount of use it receives determines how long a heat pump lasts. However, many major manufacturers offer 5-10 year warranties on the major components.
What to Look for in a Heat Pump
There are several factors to consider when purchasing a heat pump, and the US Department of Energy discusses several important considerations and features to look for including:
- Two-speed compressors
- Ensuring adequate BTUs
- The need for zone-controlled heating — especially pertinent for larger spaces
- Variable speed control
- Desuperheater or heat recovery options
- Back up burner
The biggest factors on deciding on a unit for your home remain price and size. In addition, energy efficiency is also an important factor. All residential heat pumps in the United States must have an EnergyGuide label. EnergyGuide details the unit’s efficiency rating compared to other similar makes and models. This makes it easier for consumers to make smart buying decisions.
For colder climates, choose a model with the best heating season performance factor (HSPF). Likewise, in warmer climates focus on a unit with the best seasonal energy efficiency ratio (SEER). A model with a higher rating costs more upfront, but provides savings in the long run from reduced operating costs.
Speaking to a qualified HVAC technician is the best way to ensure that your heating and cooling needs are met and any heat pump installation is completed according to local and national building codes.