I'm often asked if geothermal systems require much maintenance. The answer is a resounding, "It depends."
On one hand, a geothermal heat pump is very similar in design to a refrigerator. Sure, the capacity is quite a bit larger, but the basic design is similar. Both systems have a compressor-driven refrigerant circuit. The only moving parts in the refrigerant circuit are the compressor, an expansion valve, and a reversing valve to change with the seasons (or defrost the freezer). You also have a fan on both systems to move the heated and/or cooled air. On a geothermal heat pump we add a few circulating pumps because we are using fluid as a heat transfer medium. Think of it like a water-cooled compressor. All of these parts are extremely reliable and located inside the home. Because of this, they are not subjected to the weather, the neighborhood kids, or vandals like your central air conditioner. This gives a geothermal heat pump a longer life expectancy than your furnace or air conditioner. After all, how often does your refrigerator require a visit from the repair man?
On the other hand, a geothermal heat pump is a high performance piece of equipment. To keep it working at peak efficiency there is some preventative maintenance that needs to be performed. The biggest is keeping your air filter clean. Most contractors will install either a washable or a disposable high efficient filter with your unit. If they didn't, ask for one. The filter protects the air coil, which is your heat exchanger allowing heat or cool to be delivered to your home. If that gets dirty, the efficiency drops and your electric bills go up. If the filters have been ignored too long it is possible for dirt to become imbedded inside the air coil to the point of no return.
Another issue of a dirty coil is a plugged condensate drain. In the summer, as the unit cools your home, water condenses and runs off the air coil and down the drain. If the coil has dirt on the surface, it runs to the drain with the condensate water. Some of the dirt will settle out in the trap and eventually plug your drain. At that point your unit will shut down because of a sensor protecting the unit from a condensate overflow. A dirty filter and/or a dirty air coil will also cause your fan and compressor to work harder. This can shorten your compressor and fan motor life.
If you have an open loop system with your geothermal unit, also known as pump and dump, you should have your coax heat exchanger cleaned every year or two. Unlike the more popular closed loop systems, an open loop system uses fresh water as the transfer medium. This fresh water has a fresh supply of minerals and hardness that can precipitate out and coat the inside of your coax heat exchanger. A professional chemical flush will help remove this buildup keeping your unit working its best.
If you would prefer not dealing with air filters, most dealers offer a yearly system checkup that usually includes cleaning filters, coils, and condensate traps if necessary. Check with your dealer to see what their packages include.
This expert insight is by Doug Schuster, owner of Schuster Heating & Geothermal & Pump Co., and an Enertech Global LLC geothermal dealer.
Doug Schuster started helping his father when he was in high school. In 1984, he helped install his first residential geothermal system. In 1996, Doug took over as owner of his dad's company. Since then he has been responsible for the design and installation of hundreds of geothermal systems. In 2001, Doug won a Project of the Year award from Enertech Global for an 80,000 sq.ft. retirement home. Doug has served on the board of the Iowa Geothermal Association and was president in 2009.