Air Source Heat Pumps
An air source heat pump (ASHP) uses the outside air to heat or cool a building. When used to heat a Building, this is achieved by transferring heat inside from the outside air. When used to cool a building, this is achieved by transferring heat from inside to the outside air. To achieve heat transfer in either direction, air source heat pumps use a system that includes a heat exchanger, a compressor and means to transfer heat from one area to the other, e.g., pipes filled with a refrigerant. Air source heat pumps are driven by electricity, and systems exist that are powered by solar panels, making them both clean and energy efficient.
Cold-Climate heat pump systems heat and cool your building at a fraction of the cost of oil or propane. Coupled with your existing oil or propane heating system, these hyper-efficient and quiet heat pumps work down to sub-zero temperatures to comfortably and efficiently heat your living and working spaces. During summer months, these units reverse and efficiently keep your building cool.
Ductless, mini-split-system heat pumps (mini splits) make good retrofit add-ons to houses with "non-ducted" heating systems, such as hydronic (hot water heat), radiant panels, and space heaters (wood, kerosene, propane). They can also be a good choice for room additions where extending or installing distribution ductwork is not feasible, and very efficient new homes that require only a small space conditioning system. Be sure to choose an ENERGY STAR® compliant unit and hire an installer familiar with the product and its installation. Like standard air-source heat pumps, mini splits have two main components — an outdoor compressor/condenser and an indoor air -handling unit. A conduit which houses the power cable, refrigerant tubing, suction tubing, and a condensate drain, links the outdoor and indoor units. The main advantages of mini splits are their small size and flexibility for zoning or heating and cooling individual rooms.
For more information on Air-Source Heat Pumps visit the Mass. Clean Energy Center's Air-Source Heat pumps site which includes a guide and installation information.
Ground Source Heat Pumps
Ground source heat pumps (GSHP) use the constant temperature that exists just below the ground or in a body of water to transfer heating or cooling energy to a building. This is accomplished by transferring heat or cold from below the ground via underground piping that contains a refrigerant to a building’s heating system.
Just like any heat pump, geothermal and water-source heat pumps are able to heat, cool, and, if so equipped, supply the house with hot water. Some models of geothermal systems are available with two-speed compressors and variable fans for more comfort and energy savings. Relative to air-source heat pumps, they are quieter, last longer, need little maintenance, and do not depend on the temperature of the outside air. System life is estimated at 25 years for the inside components and 50+ years for the ground loop.
Although the purchase and installation cost of a GSHP system is often higher than that of other heating and cooling systems, properly sized and installed GSHPs deliver more energy per unit consumed than conventional systems. For further savings, GSHPs are equipped with a device called a "desuperheater" that can heat household water. In the summer cooling period, the heat that is taken from the house is used to heat the water for free. In the winter, water heating costs are reduced by about half. Depending on factors such as climate, soil conditions, the system features you choose, and available financing and incentives, you may recoup your initial investment through lower utility bills in two to ten years.
For more information on Ground Source Heat Pumps, visit Mass. Clean Energy Center's Ground Source Heat Pumps page.