[Graeme]

Assessing bids for geothermal system helped homeowner understand the technology

For example, the in-ground loop system can be installed vertically or horizontally. The first company proposed a horizontal configuration. That meant shallower drilling, but it would have spread out too far: Not only would it get too close to my septic system's drainage field, but it would have torn up most of my yard. By the time they laid hundreds of feet of piping, we would have faced a big landscaping bill. The other two companies wanted to go vertical.

Loop systems also can be open, -- meaning the fluid inside the pipes is water drawn from surface or underground sources, such as lakes or wells -- or closed. Montgomery County prefers closed systems, which don't discharge anything into the aquifer. We decided on a vertical closed-loop system.

We also decided that instead of buying a complete package from one company, we could save money by negotiating with individual contractors. To drill the holes and install the polyethylene piping and fluid, I picked Michael Barlow Well Drilling of Bel Air. Barlow has done occasional geothermal systems for years; the driller who showed up on-site told us that since the housing downturn has pretty much wiped out the market for drilling new water wells, geothermal is a much bigger part of the company's work.

washingtonpost

[frankthetank]

too expensive and the loops require lots of area... i'd only do it in new construction.

[basil_hayden]

I'm in the process of getting and evaluating bids for this currently.

geoexchange.org is a great resource, especially the forums.

I agree with Frank on the cost; without government incentives (federal, state and local) I wouldn't bother as I'm not rich.

Feds and state have tax credits up to about 30% of eligible costs. Locally, the property tax is relaxed, that is, the house is worth X more but it is appraised in town as the original value, decreasing property tax.

Also, my house which has been 1/2 finished for 20 years, is in the process of being finished, so now's the time to evaluate this system as I'd have to change over from baseboard hot water to forced hot air. Retrofitting an old house would be very cost prohibitive.

In the end however, this does not wean my house off of fossil fuels as the geothermal system will require electricity. Because of this, an alternative emergency heating system will also be needed - I'm going with a wood stove (Weso) in the basement that will heat the house when electrical service is down.

In the end, I think of it as paying 85% of my heating, cooling and domestic hot water needs for the next 20 years up front. This will only be worth it if electrical costs stay the same or increase.

[IslandCrow]

Just to say I am very happy with the ground heat exchange we had installed almost 3 years ago. As we have exposed bedrock the prefered option was to drill down (about 54 meters). The well is near the house, and I was able to do the landscaping, and dig the ditch for the pipes to the house (nearly broke my back though).

The reason to install it was the old oil-fired boiler was 33 years old when we bought the house, and I wanted to get away from using oil (as Pops used to say "what are you doing about PO?").

I agree that installing a ground heat exchange is expensive. But there will be a payback. If oil and electricity prices stay stable then for me the payback time would be around 9 - 12 years (faster if I calculate what a new oil furnace would have cost). If energy prices rise then the payback time will be much shorter. Anyway even if prices don't rise my income could fall (eg going onto pension) and the running costs of the system are much lower than other systems - so I am insuring myself against the effects of a possible price rise and of a possible fall of income. As insurance this comes cheap (but you must take a multi-year view of things not just the current business quarter)

Last year the heat pump used just over 5 500 kWh to provide our heating and hot water. The electricity company estimates that a house our size would need to use about 25 000 kWh a year if it was just heated electricially. So we are seeing a major recuction in energy bought. {For those in North America we are living at the same latitude as south Alaska so heating is important}

I also really like the controls of the system (which automatically adjusts itself for the outside temperature). The whole systems runs smoothly.

My alternative heating (and supplimentary heating in very cold weather) is a wood burning stove in the kitchen, and being Finland our sauna in the basement.

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Technically I think it is wrong to call the system 'geothermal'...the heat in the rocks / ground is derived from solar heating not from the heat of the earth's core.

[Graeme]

Answers to questions about geothermal air conditioning and heating are given at this link.