Have you heard about geothermal? It’s a simple heating and air-conditioning technology that’s been around since the 1940s. And it’s super-efficient. The most efficient gas furnace is 94% efficient, but a ground source heat pump (geothermal) is 400% efficient! That’s because a ground source heat pump uses a little energy to go get a lot of energy from the ground. In our quest for low-to-no bills, we’re very excited to have geothermal in our home.
A ground source heat pump pumps a water/antifreeze mix into a pipe loop that’s buried in the ground. Like a cave, the ground is cooler than outside air in the summer and warmer than outside air in the winter. I like to think of geothermal heat and air as renewable energy because it’s using free energy from the ground, and that free energy will always be there.
In the summer, the heat pump uses electricity to pump the water mix into the ground loop. The water mix coming out of the house is hot – it contains the heat that we’re trying to get rid of in the summer. As the water mix travels through the ground loops, it cools because the ground is about 55 degrees. That cool water returns to the house, and the heat pump delivers cold air to the home – air conditioning! It works the same in the winter, except the water mix leaving the house is very cold, and it gets warmed up when it travels through the ground.
We’ve been really interested in geothermal for a long time, so interested that we scrounged around and drove all the way down to Georgia to get a great deal on a 6-foot blade Ditch Witch. One look at the beast, and we named it “T-bone”. We used T-bone to trench four trenches that were 220 feet long and 6 feet deep each. We laid black water pipe in the trenches – 6 feet down going away from the house and looping back at four feet down coming back to the house. We pushed the dirt back into the trench and tamped it hard so the dirt would have great thermal contact with the pipe (the water mix will cool/heat faster). All the pipes are connected together in a manifold and brought back to the house. The total length of pipe is about 1,780 feet. The water mix will travel that whole length before returning back to the house.
Next steps are duct work and installing the ground source heat pump inside the house. With a small house, loads of insulation, and geothermal heating and air, we’re really excited to see how low our electric bill will be. Wish us luck!