How heat pump works

Discover the principal of heat pump operation and what makes a geothermal heat pump so energy efficient.

How Heat Pump Works

The exchange of energy in geothermal system is done by the heat pump – the device that works similar to the refrigerator. The heat pumps, refrigerators and air conditioners all work in the same manner: by pumping the refrigerant through a closed loop (ground loop in geothermal systems), that has two distinct temperature zones – cold and hot.

There a few thermodynamic principles that are used in heat pump’s work. First of all the heat always flows from higher temperature zone to the lower. The heat pump reverses this natural flow making the heat flow from the lower temperature zone to the higher, and by doing that heat pump consumes energy, that is why it is called “pump”. Basically geothermal heat pump is the same refrigerator with a few distinct exceptions: the desired effect for the heat pump is heating and the effect of the heat pump can be reversed to provide either heating or cooling.

When the heat pump heats, antifreeze from the ground loop (loop field) flows by the heat exchanger tubes, containing refrigerant that is cooler than the antifreeze. Since thermodynamics laws say that heat is transferred from the hotter zone to the cooler, refrigerant in the pump’s tubes absorbs the heat from the antifreeze and evaporates within the tubing. The cool refrigerant vapor is than compressed and pumped to the heat pump’s section that has high temperature and often has a refrigerant coil with air blower across it. Since refrigerant gets hotter when compressed it becomes hotter then the relatively cooler air in the space thus giving up heat to it. After refrigerant gives up heat to the air stream it becomes cooler and condenses back to the liquid. The liquid then is pumped through the flow restriction that maintains the pressure difference between cold and hot zones. As the pressure of the liquid drops, it vaporizes becoming cooler and it is ready to go through the refrigerant process again.

If the heat pump works in the cooling mode the process can be reversed – the cold and hot zones then are swapped. With the cold and hot zone reversed the heat pump extracts heat from the indoor air and then rejects it to the ground loop field.

In a geothermal heating and cooling system, heat pump plays an essential role of extracting and delivering ground source thermal energy from a heat exchanger, to the interior space of your home. It is important to choose the correct size heat pump for optimal operation of your geothermal system.

This entry was posted on Tuesday, December 7th, 2010 at and is filed under Geothermal Heating and Cooling. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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