Installing horizontal ground loops. Photo by Steve Ehrman.
This is part two in a three article series on geothermal heat pumps. Part one can be found here.
Our geothermal installation took five days and was followed by an inspection and training session. The amount of time and effort involved in setting up a new system varies, depending on the location of your existing heating and cooling units in relation to where the ground loops enter your house, and on the location and configuration of your ductwork, electric wiring, and hot water heater.
We awoke early in the morning as the ground loop installation crew arrived. A large flatbed trailer parked in front of our home, carrying an excavator and a compact track loader. This day’s work consisted of digging the horizontal trenches for the ground loops, laying the loops, replacing the removed soil, and running the loops into the back of the house.
In total, our Water Furnace required four 150-foot horizontal trenches, each five feet deep. These were joined at the end of our yard by a “header” which routes the water/antifreeze mixture from the house through each of the loops in parallel and then sends the heated or cooled mixture back to the house.
It was a little disturbing watching our entire back yard being dug up so quickly, but we were excited and took more photos and videos than was probably necessary. We had been told by a neighbor that he had been present during the original construction of our home and had never seen such rocky soil in his life. So we were a bit nervous that the condition of the ground would add extra time and expense to this portion of the installation, especially since our contract stated that this could be a possibility. Luckily, the large excavator easily handled the stones and the workmen said our yard wasn’t anything out of the ordinary.
By the end of the day all of the loops were in place, along with the header, and they had been filled with pressurized air and left for the weekend to make sure there were no leaks.
The crew returned early on Monday and began by confirming that the ground loops had maintained pressure. This day consisted mostly of removing our existing heating and cooling systems and beginning to make alterations to the ductwork to accommodate the new unit. Our home was built in 1977 and the positioning of some of the ducts in the utility room had us scratching our heads because one glance was enough to see that they were inefficiently and poorly placed. Our geothermal company reconfigured the ductwork nearest the location of the new furnace at no additional charge.
If you are replacing an oil tank, you will need to check with your geothermal company to see if they will remove and dispose of it. Our company did not provide this service, but that wasn’t a problem for us since the previous owners had completed that process already. Our company did, however, remove and dispose of the interior furnace and the exterior air conditioning unit. This was probably the noisiest day of work inside the house, and the workers opened the windows and doors to the basement while we set up fans to help remove the smell of oil from the old furnace. I can’t tell you how glad I was to see that old system go.
The third day was spent installing the new Water Furnace, connecting it to the header for the ground loops, and beginning electrical updates. Our setup consists of a Geolink variable flow center which pumps the water/antifreeze solution through the ground loops to and from the 5 Series Water Furnace. The furnace uses a compressor to heat and cool the house and also sends supplemental hot water through a separate loop to our water heater using a desuperheater (DSH) generator. A Little Giant pump removes any water that condenses during the heating and cooling cycle, sending it out into our yard through a drain pipe. It is all controlled through a Water Furnace color touchscreen thermostat which was installed in place of our old thermostat and provides us with information on temperature, humidity, furnace and fan settings, and real-time cost and energy savings calculated by entering local electricity costs.
The big day had finally arrived! It was now time to fill the loops with water and ethanol and finish the electrical and duct connection. When I got home from work that afternoon the installation crew had already left for the day and my mind was preoccupied with other matters. As I stepped into the house, my first thought was, “Geeze! Why is it so cold in here?!” Then it hit me. The Water Furnace was running and the icy cold air rushing through the vents was being cooled by the ground loops in our own yard. Nothing beats the satisfaction of knowing you’ve made your home more comfortable and more efficient.
Refilling and smoothing the ground loop trenches. Photo by Allison Ehrman.
The final task of installation consisted solely of running heated water from the Water Furnace to our existing hot water heater. This took a full day’s work in our home because our water heater is on the opposite side of the basement from the furnace room. The geothermal company ran pipes from the furnace to our existing 17-year-old water heater, and connected them via a valve at the bottom of the tank. This plain water is warmed in the DSH and is completely separate from the closed outdoor loops. This function was optional with our installation, and only serves to supplement the hot water heater when there is a surplus of heat from the geothermal system.
By the end of day five, the system was completely in place and running. And due to a timely weather transition, we went from cooling our house with geothermal the day before to heating it with the same system the following day.
A week after the work was complete, the county sent an inspector to take a look at the installation. This was a very brief walk-through, as the geothermal company had taken care of all required permits throughout the entire process. The company also sent an expert to our house to train us on using the new system, which is a critical step for getting the most in energy and cost savings from the setup. I will go into our experience managing and living with geothermal in the upcoming third article of this series.
If you live in Northern Maryland and are looking for a reliable geothermal company, I recommend the services of Ground Loop, Inc.
Allison Ehrman works in the corporate world, but her heart and soul reside in her Northern Maryland country home, where she and her husband grow and preserve herbs and vegetables, prepare exotic dishes from locally-sourced foods and craft natural body care products. You can read more of her Mother Earth News articles here.
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