How Do Heating & Cooling Pumps Work?
Heat pumps work to both heat and cool the air that passes through them. Heat pumps not only transfer heat both ways, they use a combination of different sources of heat. Sometimes they use the outdoor air, and sometimes they use heating elements contained with the system itself. This allows them to save energy but also provide the temperature changes required for the house. Does this Spark an idea?
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Heat Pump Systems
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While a heat pump is one system, it is made up of many different devices, including fans, drains, compressors, heat exchangers, evaporators, condensers and expansion valves. For a medium to transfer heat, the pump uses a refrigerant gas. All these parts must work together for the heat pump to function. This is one reason that many heat pump problems can be difficult to diagnose.
Air Process
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The air passes to the heat pump through vents throughout the house, where it flows across the heat exchange fins of the pump. These metal fins are hot when the pump is heating the air, allowing the heat to flow from the metal to the air itself. When the pump is cooling, the fins are cold and absorb both heat and moisture from the air (the moisture flows into a drain below the pump). The air is then blown back into the house by the heat pump fans.
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Refrigerant Process
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The refrigerant travels through a closed loop continuously, cycling through the heat pump as needed. It is compressed by the compressor to raise its temperature, then flows through the evaporator to heat the air. It cools down so much it changes from a gas to a liquid, and must gain heat and change back into a gas to make it through the expansion valve. The gas is condensed to make it colder so it can draw heat from the air when necessary.
Efficiency
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Heat pumps have different levels of efficiency, depending on how well they transfer the energy they use into actual temperature change in the air. A pump that can transfer around 80 percent of its energy directly into temperature change is considered efficient--the most efficient devices are electric furnaces, which can approach 100 percent efficiency.
Other Types of Heat Pumps
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The two other types of heat pumps, besides the ordinary air and electric element version, are the geothermal and solar versions. The geothermal heat pump is a more complex system that draws in heat from the earth itself to heat the air when necessary--these pumps work better in cold weather and have higher efficiency ratings. Solar heat pumps supplement heat from energy collected from the sun, so they work best in sunny climates but can cut down drastically on electricity usage.
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References
- Photo Credit condensseur image by photlook from Fotolia.com
