Originally published on December 7, 2012
You might have read or heard about geothermal heat pumps and how they’re gaining a lot of popularity. But what does “geothermal” mean and how does this system work?
Geothermal heat pumps work along with the same principles as standard heat pump systems with a few important exceptions:
The role of the heat exchanger
The components found in a typical geothermal system closely resemble that of a heat pump system. Components like the compressor, metering device, and indoor coil all perform the same basic functions. One important exception is that the outdoor fan coil has been replaced in a geothermal system by a heat exchanger.
A heat exchanger, as the name suggests, takes heat from the system’s refrigerant and transfers it to circulating water.
Drawbacks of standard heat pumps
Standard central air heat pump systems typically consist of two parts, an indoor and outdoor unit. The indoor and outdoor sections rely on air being forced across their coils in order to transfer heat to the surrounding area.
One drawback of this design is that the system can meet limitations as the outdoor temperature reaches extremes. This is most common with a standard heat pump system in winter. As the outdoor temperature drops below 25°F, it reduces the heat pump’s ability to provide warm enough air to the home. While the supply air is warm enough to heat your home, it may feel like “cold heat” when you feel it coming out of your vents.
The key difference: outside air temperature is largely irrelevant
Traditional heat pumps must absorb as much heat as possible from the cold outside air. By trading the outdoor unit with a piping loop in the ground, the outdoor ambient temperature does not affect the geothermal system’s temperatures required for heating and cooling. The ground remains at a pretty consistent temperature in the 50’s all year long. This design allows for geothermal systems to provide warmer supply air to the house and a very high level of system efficiency, regardless of how cold it is outside. The outside temperature now only impacts how fast or slow your home loses heat.
The geothermal heating system in action
When heating is needed, water is pumped through a series of underground pipes located externally to the house and absorbs heat from the ground. The system’s compressor pumps refrigerant into the heat exchanger where the heat captured in the water is released to the refrigerant. The indoor coil transfers the heat from the refrigerant to the air in the house through the ducts/vents. Now that the refrigerant released its heat, it goes back through a metering device and returns to the heat exchanger to pick up more heat from the water.
For many facility managers, geothermal heat pumps are the key to increased comfort and efficiency in their buildings and homes. Did you know you could save so much energy getting your heating and cooling from the ground instead of the air?
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