Long used for cooling in warm climates, heat pumps are now one of the fastest growing technologies for ultra-efficient heating in cold climates. reVision heat’s Chris Kessler joins us to share more information about Air Source Heat Pumps — an efficient alternative for keeping your home comfortable in the summer and winter.
SRG: What is a heat pump and how does it work?
CK: A heat pump uses refrigerant to transfer heat energy between the conditioned space and outdoors. In the summertime, heat inside of a home is absorbed by the refrigerant and transferred outside. In the wintertime, the cycle is reversed. As outdoor temperatures get colder, the refrigerant flow decreases – however, heat pump manufacturers have developed their compressors to transfer ample heat with outdoor temperatures as low as -15°F.
Heat pumps have also been adapted to heat hot water tanks. When the water temperature falls, the water heater activates and pulls heat out of the surrounding air. Through the refrigerant cycle, heat is transferred into the tank. As the heat pump heats the water it pulls humidity out of the air, which will reduce or eliminate the need to run a dehumidifier in the space if you use one currently.
SRG: What type of building/home/office is the best fit for a heat pump?
CK: Heat pumps can be used in many applications, whether it is to provide space heating/cooling for individual rooms or to serve as the primary heat source in a building. They work well in existing or new construction. Which heat pump system works best depends on the desire of the individual, existing heat sources, floor plan and how well insulated/air-sealed the building is. Heat pumps also come in a variety of forms with their own applications:
- Mini-split heat pumps like the Mitsubishi or the Fujitsu systems, where refrigerant lines are run from one exterior condenser to indoor units, are best in houses that are well-insulated and air-sealed and total loads of less than 44,000 Btus. Houses with fewer rooms and open floor plans are better served by mini-split systems. reVision heat has developed a system using Energy Recovery Ventilators (ERVs) to provide both fresh air and back up heat to supplement heat pumps in remote rooms that don’t have an output head.
- Centrally-ducted systems can be a great alternative for a house where cooling is required and where loads are up to 50,000 Btu/hr. Modern air handlers have modulating fans, with communicating thermostats, which makes them incredibly quiet; you don’t notice the air moving in the home. The advantages of centrally-ducted systems are many: they allow heat recovery ventilators, air conditioning, and whole house filtering to be incorporated into the same ducting system. These systems typically need to be backed-up with electricity or propane.
- Air-to-water heat pumps are a great solution where low-temperature distribution like radiant floors are the desire of the individual. These heat pumps can make hot water up to 120 degrees. They require some back up electricity when higher temperatures are required, or when loads exceed 36,000 Btu/hr. We use the Daikan Altherma for houses where radiant heat is desired, but where loads are not excessive.
- Heat pump water heaters are an energy-efficient and cost-effective way to produce hot water. If you are producing your hot water with an oil boiler, you have an opportunity to reduce your oil use by about 200 gallons a year. They operate at about 240% efficiency compared to an electric water heater, and cost about $200/year to operate for a family of four.
SRG: How much does a heat pump system cost for an average size home?
CK: It depends on the scenario. For example, an 1800 SF home can install a single-zone mini-split system that provides about half of the home’s heating and all of the cooling needs for about $4,000. Each home, however, has it’s own heating and cooling loads which are influenced by many factors including number of windows, shade cover, and energy efficiency. The only real way to know how much a heat pump system will cost is by having an energy assessment done for your home.
SRG: Are there any state or federal incentives or tax credits that apply to heat pumps?
CK: There is a $300 Efficiency Maine rebate for all heat pump water heaters installed between January 25, 2013 – June 30, 2013. There is also a tax credit of up to $300 for some models of heat pumps and heat pump water heaters.
Chris Kessler is a Technical Salesperson and Energy Auditor for reVision heat. He specializes in Building Science and loves helping people reduce their fossil fuel consumption and save money. When he’s not working, he enjoys hanging out with his family and talking long walks with his wife, daughter and dog along the Greenbelt Walkway in South Portland.
