How Direct Exchange (DX) Geothermal Systems Work
Reducing the number of heat transfers directly increases heat output and efficiency.
Geothermal utilizes the heat stored in the earth from the sun’s energy. In order to capture this heat energy a geothermal system requires multiple heat transfers to move the heat from the earth into usable heat for your home. Therefore reducing the number of heat transfers directly increases heat output. In a traditional water geothermal design there is a total of 3 heat transfers, whereas a direct exchange (DX) geothermal only has 2 heat transfers. By reducing the number of heat transfers, a DX geothermal gains extra heat that would normally be wasted. Eliminating waste, results into higher heat output. More heat means less run time, lower operating cost, better comfort, and bigger savings than a standard water geothermal design.
A Standard Geothermal System has three heat transfers
Step 1: The heat from the earth is transferred into the geothermal loop fluid which is a water/antifreeze solution. A water geothermal design requires a water circulating pump to achieve this process.
Step 2: The heat is transferred from the water/antifreeze solution to the refrigerant (Freon) inside the geothermal unit. This step requires an extra heat exchanger to achieve this process, which can be very costly to repair when they fail.
Step 3: Finally heat is sent from the refrigerant (Freon) into the air blowing across a copper radiator type heat exchanger and into the air duct system in your home.
The conductive properties of copper are recognized industry-wide, which is why every waterless & water source geothermal manufacturer today utilize a conductive “Copper Radiator” type coil to perform this final step, which delivers warm comfortable air throughout your house.
A DX Geothermal System only has two heat transfers
Step 1: A DX geothermal heating and cooling system transfers the heat from the earth directly into the geothermal loop fluid which is the latest environmentally friendly refrigerant (Freon).
Step 2: The heated “Freon” is sent inside the house and heat is transferred into the air blowing throughout the ductwork in your home. The Final heat transfer that takes place in every geothermal manufactured today utilizes a conductive copper radiator/coil where air passes through to achieve this step.
A DX geothermal system skips the step where heat is being transferred from the water/antifreeze to the refrigerant.
Another benefit of the DX geothermal system is the copper ground loop, which is a more effective means of transferring heat than the plastic ground loop. Copper has a heat transfer rate that is over 1000 times greater than plastic, at 227 versus plastics .0225.
Consider the following example using a real world example. Picture a copper bottomed pot, just like the ones you use to cook in. The bottom of the pot that is designed to heat up and transfer heat very quickly is made of copper. The pot’s handle is designed to act as a heat barrier and to protect you from getting burnt.
How it works
The heating and cooling geothermal system utilizes the naturally occurring temperature of the earth to provide heat in the winter and cooling in the summer.
Check out the videos below to see each mode in action:
DX Geo Heating Mode
DX Geo Cooling Mode
- Refrigerant is pumped to the outside and circulates through the copper ground loop
- The heat energy stored in the ground is transferred through the copper tubing and into the environmentally friendly refrigerant as it flows through the copper ground loop
- The compressor pumps the heated refrigerant from the ground into the house sending it through the indoor coil installed in the air duct system
- The coil heats up from the hot refrigerant circulating through it; then the air from the air handler passes over the heated coil and the heat is transferred into the air as it enters the Warm Air Supply.
- The heated air from the Warm Air Supply is distributed throughout your air duct system to all of the rooms in your home
- After the refrigerant releases the heat into your home the refrigerant is sent back out to the ground loop as a cooler refrigerant to pick up more heat and the cycle starts all over again
During the cooling cycle the refrigerant reverses direction and the heat from your home is sent to the 55˚ ground resulting in a comfortable and cool indoor environment while the outside ground begins to store the heat for the winter months.