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Topic:	Heat Pump Technology
Source:	SRP Utilities, Salem Electric
Web Site:	http://www.srpnet.com/energy/pumpworks.aspx#video

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What Is A Heat Pump

A heat pump is a ducted forced-air heating and cooling system. It is called a "heat pump" because it moves or "pumps" heat from one place to another. Using a compressor and a circulating system of liquid/gas refrigerant, heat is extracted from outside sources and pumped indoors. The advantage of pumping heat is that it uses less electrical energy than converting electricity into heat. In the summer the cycle is reversed and the unit operates like an air conditioner. Heat is extracted from the inside air and pumped outdoors.

Heat pumps are considered by many to be the most efficient choice for heating and cooling systems. A heat pump supplies more heating and cooling capacity than the amount of electrical energy used to run it.  The efficiency rating of heat pumps can be as high as 300%.


How Heat Pumps Work

An electric heat pump can heat your home during the winter and cool it during the summer. The major parts of a heat pump include:

• Compressor: This increases the pressure of the refrigerant so that it will accept the maximum amount of heat from the air.

• Condenser: Coils that move heat to or from the outside air.

• Evaporator: Coils that move heat to or from the air inside the home.

• Air handler: Fan that blows the air into the ducts of the home. Components 1, 2, 3 and 4 are found in all standard air conditioners.

• Reversing valve:Changes the heat pump from air conditioning to heating, and vice versa. This is not part of the thermostat.

Types Of Heat Pumps

Most heat pumps have two main parts, the outdoor unit and the indoor unit. The outdoor unit includes a heat exchanger, compressor, and a fan. This is where heat from the outside air is transferred inside during the heating season, and where heat from inside the home is transferred out during the cooling season. The indoor unit contains a heat exchanger and a fan that distributes heated or cooled air through the duct system into the home.

Air Source: An air source heat pump (the most common type) gets heat from the outdoor air and usually consists of an outside unit connected to an indoor unit. Ductwork is connected to the indoor unit to supply the heated or cooled air to the rooms in the home.

Geothermal: Geothermal heat pumps consist of ground source and water source. Ground source heat pumps use heat from the ground rather than from outdoor air. An advantage to this type is that the ground is a constant temperature without the common fluctuations in air temperatures. A ground source heat pump is less expensive to operate than an air source. These systems have a higher initial cost than air source and the installation requires some excavation to install pipes in the ground.

Water Source: Water source heat pumps use a body of water; either well water, a pond, or a stream for their source of heat. They absorb heat from the water, which is usually warmer and more stable than winter air. Efficiency is higher with this system compared to the air-source heat pump, but initial investment is also higher.


Heat Pump Video Clip

This video clip explains how heat pumps work and can help you decide if a heat pump is right for you.

To view it, you need Apple QuickTime Software