Dear Angie: I have a ground-source geothermal heating and cooling system. This summer, we’ve endured a significant drought and heat wave in our area and I’ve noticed our geothermal system has not been effectively cooling our home as it normally does. I know the unit relies on steady ground temperatures to dissipate heat. Could the dry ground and extreme temperatures be affecting the performance of the system? – Cathy H., Carmel, Ind.
Dear Cathy: Unfortunately, some homeowners with geothermal systems are experiencing problems with the units not sufficiently cooling their homes. The dry ground and high temperatures definitely is impacting how well some units perform.
Ground source geothermal units use an underground loop system to bring heat from the earth into the home during the winter and pull heat from the home back into the earth during the summer. Loops can be buried vertically or horizontally, depending on the type of soil, size of the yard and other factors. Systems with horizontal loops seem to be impacted more by the dry conditions, because they’re not buried as deep into the earth as vertical systems. The ground needs to be moist and cool for the system to operate as it should.
Obviously, that’s been a major problem in parts of the U.S. this summer with the lack of rain and the unusually high temperatures at night, when the ground is normally able to cool off.
Though the extreme weather could be why your system isn’t performing up to its normal standards, it could also be related to how the system was installed and the number of loops put in during the installation. Systems that aren’t sufficiently sized to handle extreme weather conditions won’t operate as efficiently. That’s why it’s important for homeowners adding new systems to hire qualified companies who are trained and experienced to work with that specific system and who properly calculate the heating and cooling load needed for your home.
Unfortunately, there aren’t many solutions for homeowners with geothermal systems struggling to meet the cooling demand. If you don’t have watering restrictions, then soaking the ground where the loops are could solve your problem. If you are under restrictions, you could explain your situation to your water company and ask for an exemption. You could look into having a geothermal company add more loops deeper into the earth; however, that would be a major investment for an occasional problem. A simpler solution could be to install a backup cooling source, like a window air conditioning unit. I recommend you talk with a reputable geothermal specialist who is trained and qualified to work on your specific equipment to see what your options are.
Fortunately, the extreme weather conditions shouldn’t cause any permanent damage to the unit. The systems are designed with safety mechanisms in place that automatically shut the unit down when it senses conditions are too extreme. If your system shuts down, you can have your installer check the water and air flow and refrigerant levels. If those check out, the installer will likely recommend you reset the unit to operate at higher temperatures, for example, raising your thermostat setting from 75 degrees to 78.
Though this is an issue this year for some geothermal owners, you shouldn’t experience problems with heating during the winter if temperatures get too cold outside. Geothermal systems come with a backup source to provide heat if the geothermal can’t sufficiently provide it.
Angie Hicks is founder of Angie’s List. Have a question for her team? Email firstname.lastname@example.org or tweet to #AskAngie. Follow her @Angie_Hicks.
Do you have a geothermal unit, and if so, how do weather conditions affect it? Tell us about your experiences in the comments below.
Editor's note: This is an updated version of an article originally posted on Aug. 6, 2012.