What In The World Is A Heat Pump And How Does It Operate?
Serving as both furnace and air conditioner, heat pumps provide a unique heating system. At present, there are only two types of air pumps in general use for the home, air source and ground source.
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The principle behind the heat pump is fairly simple. Heat naturally flows from warm to cold, high to low. With a small energy requirement, a heat pump reverses the process by pulling heat out of a heat source and pumping it into your home.
Air-Source Heat Pumps – In its most basic form, the air-source heat pump system is like a reverse air conditioner. Domestic systems have both an indoor and an outdoor unit which connect through the wall.
An air-source heat pump, in heating mode, evaporates the refrigerant in the coil in the outdoor unit. During evaporation and resultant cooling, the refrigerant absorbs heat from the outside air. The heated refrigerant passes in a compressed form into the indoor coil where it condenses and releases heat.
In essence, the pressure changes caused by the compression and expansion of the refrigerant allow the refrigerant to evaporate at a low temperature outside and condense with higher heat content (temperature) indoors.
The reverse valve is a crucial part of a heat pump because, with the change of a thermostat setting, it reverses the flow of the refrigerant and the system provides cool air to the air ducts.
Ground-Source Heat Pumps – In a ground-source system you have the same kind of heat exchange taking place. The difference is that in the ground-source system the outdoor “refrigerator” coil is replaced by underground pipes filled with refrigerant.
When it is in heating mode, the ground-source heat pump pulls heat from the ground for circulation indoors. As with the air-source heat pump, ground-source heat pumps have a reverse valve. When reversed the system becomes an air conditioner.
The major differences between the air-source pump and ground-source systems are the cost and source temperature. Ground-source systems can cost as much as three times as much because of the expense involved in running the pipes.
The air-to-air system is limited to moderate climates because running the heat exchange system takes too much energy in a more extreme environment. But temperatures just two or three feet in the ground remain quite constant almost anywhere in the U.S. so the ability of a ground-source system to transfer heat from this medium is not nearly as restricted in harsher climates.
In either case, heat pumps can reduce utility bills by between 30 and 40 percent. Government incentives will often defray part of the cost of installation. When installing a heat pump look for higher SEER and HSFP ratings.
For Northern Virginia advice on heat pumps and other heating or air conditioning systems contact F.H.Furr Plumbing, Heating and Air Conditioning – the number one Northern Virginia plumbers offering Fairfax plumber and service in Reston and McLean.