Jim Rooney On The Level

Q. Do you have any knowledge or experience with geothermal heat pumps? Not so much about how they work or how energy efficient they are; I have read about those things. What is hard to find out about is are those systems mechanically reliable in the long term?

A.You are wise to be wary. The road to progress is paved with the bones of pioneers. I have inspected them as part of performing home inspections and have attended all day seminars with them as the only subject and I can tell you that the simple answer is yes they are mechanically reliable IF they are designed and installed properly by designers and mechanics who not only know what they are doing but care about what they are doing. They have to perform long after any installation warranty is up to justify their cost.

The track record is good but they tended not to have been installed in homes at any great rate due to simple parameters, mostly surrounding initial price and site conditions. When I first began looking at them they were most advisable for owner operated buildings of 10,000 square feet or more. So they tended to be installed in schools, municipal buildings, health facilities and the like.

Ground zero for geothermal heating-- also known as ground source heat-- in the U.S. was out in the Midwest years ago. If you’ve ever experienced a few winter days out on the American prairie in Iowa for example you’d soon know why our common air-exchange type heat pumps just couldn’t cut it out there.

The basic energy exchange mechanism is via buried lines, either through trenches dug to a specific depth or vertical wells into which sealed plastic pipes are filled with a liquid-- like anti-freeze-- running through them to effect the thermal exchange. In some instances the lines can be placed into a water source such as a large pond if the depth is enough. As you can see the system design is very dependent upon site conditions. There is a thriving geothermal movement on the Eastern Shore and I’m sure the amount of available land has lots to with it.

The move towards energy efficiency at all levels has begun to make them more attractive to homeowners. I have read that geothermal systems have even been employed in some Habitat for Humanity homes where the lots were amenable to their installation. Ikea is installing a geothermal system in a new 450,000 sq. ft. building in Colorado and claims of efficiency are nothing short of astounding over traditional heating and cooling. They’d have to be. They are installing 130 500 ft. deep wells to supply the system.

I have begun to see TV spots for geothermal installation and that’s a good sign. We will see what happens. If we still see the ads after a long stretch of time then that’s a good indication they are selling. The other good point about local firms advertising geothermal installation is that it indicates there is now a population of folks who know how to work on them. In the past they were almost one of a kind installations in residential applications.

The main down side issues I've seen in the past were common problems such as leakage at pipe connections. They are, as you know, heat pumps that use a very temperature stable medium for extracting heat or shedding it, depending upon mode. My sense is the heart of the system, the heat pump, will last longer than a common air medium employing system.

I can’t give you an exact payback period for a geothermal heating and cooling system over the traditional air exchange heat pump but I know they use less energy so they’ll lower electric bills and you can get tax credits for putting one in. My advice is that if you do, plan to live in your house for a long time to actually reap the benefits of geothermal living. I’ve seen claims by the International Ground Source Heat Pump Association that some payback periods are as short as three years. I considered the source of that claim and took it with a good bit of salt.

Keep the mail coming. If you've got a question, tip, or comment let me know. Write "On The Level," c/o The Capital, P.O. Box 3407, Annapolis, MD 21403 or e-mail me at jimrooney@jimrooneyonthelevel.com or inspektor@aol.com.