Geothermal Heating and Cooling — A Progress Report

In response to last year’s post about making the switch to geothermal heating and cooling, I receive occasional inquiries about our level of satisfaction with the system. Most recently, Tami wrote to ask for some help as her family is considering whether geothermal will be appropriate for their 1820 farmhouse in Maine.

Here’s the bottom line question: Would you rather…..
a. pay $1162 for propane (not counting electricity) for heating for six months, OR
b. pay $886 for heating and cooling for one year

If you chose (b), you chose our geothermal system.

We are delighted with our system and we think that nearly anyone else would be, too. However, there are a number of variables to consider when determining the cost-effectiveness of a system. You can start by visiting the Geothermal Heat Pump Consortium, to obtain information about geothermal systems. For those who own old homes (such as an 1887 farmhouse) where there are some special considerations, this slideshow of case studies for installation in historic buildings is reassuring.

Here’s an illustration of how a geothermal system works for cooling:
(click on the image to enlarge it)

Source: Geothermal Heat Pump Consortium, Inc.
We live in an 1887 farmhouse. The house has Tyvek wrap and siding, windows that range from original to modern vinyl, doors that range from original to modern steel, and the original wood flooring. New insulation was added to the attics in 2007. We live in the rural midwest, where there is precious little to slow those winds that come sweeping down the plain. In the winter time, it is not uncommon to go through several weeks of temperatures well below zero. We still have a long way to go to maximize our energy efficiency — and can afford to do so with the savings from our geothermal system. What follows is our experience; your mileage may vary.
1. Getting an estimate: the representative from Peters measured the square footage of the house and examined the state of our insulation, windows, and doors. He gave us a list of recommendations that would improve our energy efficiency and comfort, with the most important being to put new insulation into all of the attic spaces. He then calculated our heating/cooling load and estimated the cost of various alternatives (gas, electric, geothermal). He walked us through the calculations and then left us the estimate along with a long list of references.

We called five of the references and got rave reviews about both cost and comfort. We have since heard about one home in our area where the homeowner was not happy. In that case, which was new construction, the square footage of the house was at the breakpoint between two sizes of furnace and the owner had elected to go with the smaller, slightly less expensive size. Lesson learned: if you’re near the maximum load of a furnace, opt for the larger size. This assures comfort and flexibility should you add on to the house in the future.

2. Upfront cost: The total cost of equipment and installation was $14K. This included a WaterFurnace geothermal unit, new ducting, piping and installation. Our rural electric power company, WIEC, gave us a $2ooo rebate incentive for this purchase and a discount on two new water heaters. (We needed two water heaters to take advantage of the hot water generated by the geothermal heat exchange.) WIEC also offered a low-interest loan for the furnace, and, as further incentive, meters the geothermal system separately at a discounted rate. Finally, we were able to take a tax credit on our federal return for energy efficiency improvements. Be sure to check with your electric company and state for possible incentives and rebates for geothermal systems.
2. Upfront inconvenience & bother: installations into existing homes are also going to involve some cost to landscaping. Our system involved uses a closed horizontal loop which required a narrow trench leading from the house, across the driveway, and into the pasture — see the red line in the photograph below. Vertical loops are possible where there is not enough room for a horizontal installation, but will cost more. Total installation time took about a month due to the need to coordinate the work of the electric company, trenching company, and furnace dealer. Actual labor was only a few days. Several months following the installation we had to have our gravel driveway regraded due to settling over the trench, and reseed the disturbed lawn areas.
3. Comfort and satisfaction: The system is so quiet that most of the time we’re not even aware that it’s on. The amount of dust in the house is noticeably lower (and that’s saying something for an old farmhouse on a gravel road). Best of all, we are warm in the winter and cool in the summer. We keep the temperature in the low seventies in the winter (with temps below zero on a regular basis and constant winds), and in the upper seventies in summer — settings that would financially cripple us if we were still on propane heat and window air conditioning. Even with those settings, the geothermal’s demand for electricity is still lower than traditional systems — which is why our electric company provides incentive for purchase.
4. Operating costs: Until recently, our electric bill separated the cost of the geothermal system from the remainder of electricity used to operate the household, machine shed, barn, security light, and fencer. Our highest air conditioning bill, in July 2007 when average highs were in the upper 90’s, was $25. Twenty. Five. Dollars. Our highest heating bill, in the depths of a miserably cold January, was $135. Over the past year, our bill averages $74, for a total of $886. By comparison, from August, 2005 until February 2006 (when we switched to geothermal), we shelled out $1162 for propane. Since that date, we have used less than 15% of our tank to fuel our kitchen stove. (I love to cook with gas, I’ll never give that up.)
Any more questions? Post it in the comments section and I’ll update the post.

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