Saturday, January 24, 2009

A Response

From Jack Stephenson's letter posted at GilfordGrok, about the proposed geothermal HVAC system for the Gilford Police Station project:

To Gilford voters, Selectmen, and Police Facility Committee (FPC), 1-21-09.

I’ve been searching for information to justify using geothermal energy here in Gilford with the coldest ground in the USA. Can’t find any. The best data I can find says that if the ground water is at 45 deg F then the heat you get is only the heat of electrical energy you put into the pumps, and the ground water in Gilford is 40 deg F or less. It is thus easy to understand that our Selectmen rejected geothermal heat for the Town Hall when shown that just the interest on the investment to install it was double the cost of current oil heat.

How then is it possible that the FPC decided to use geothermal heating, when their big goal was to reduce costs? They have not shown us any data to justify that outrageously high cost. The new library has geothermal heating, and the only information we’ve gotten so far is that it is difficult to regulate. Absolutely nothing about cost versus return.

The Town hall uses hot water heating to radiators, the healthiest heating system, since it avoids blowing pollutants, dust, pollen, mold spores, etc thru the facility. The FPC shows using expensive heat exchangers, blowers, and steel ducting to distribute the heat. Where is the economic justification? Just "business as usual, damn the cost, full speed ahead"?

More amazing is the use of just one well, and return cold water going back side by side with the pipe for ground water (thus chilling it), and then back into same well. Seems like sci-fi magic. For less than 2% of the cost for geothermal installation they could insulate enough so they could heat for 5% of the geothermal operating cost!


NOTE: I must say up front that I am not responding to Jack's letter as a member of the Gilford Facilities Planning Committee. This is not a response sanctioned by nor known in advance by members of the FPC. This is my personal response to Jack's series of disparaging and misleading letters to the newspapers in the region.


Unfortunately, Jack has got it wrong.

Since he seems to have trouble reading the “incomprehensible plans” for the police station project, let me enlighten you.

First, the geothermal system will not be using ground water as Jack defines it as the water source. The geothermal well will be a 1500 foot standing column well, not the shallower well as originally envisioned.

At 1500 feet the temperature of the surrounding rock, gravel and water is a balmy 50 degrees. At 200 feet the water temp might be 40 degrees, but not at 1500 feet. My proof? The geothermal wells at the library and at the Audubon Society's Prescott Farm. The same is also true of the geothermal wells at the Merrimack County Nursing Home. They run approximately the same depth and the temps at the bottom of those wells is about 50 degrees.

Second, in regards to the "ridiculously high costs", where does he get his numbers? The upfront costs are indeed higher. That was understood from the beginning. The payback period from the system was estimated to be 5-7 years based upon oil costs of $2.20 per gallon. The actual operating costs are a fraction of traditional combustion-based/external heat exchanger HVAC systems, like the one that presently exists at the town hall/police station. So are the maintenance costs. (Combustion systems require more maintenance, as does equipment exposed to the elements 24/7.)

Jack says it is difficult to regulate. Does he base this claim upon what was said by Katherine Dormody at the Board of Selectmen meeting on the police station bond? If so, he didn't listen very carefully. Because the library is using radiant heat and not a baseboard or fan-coil based system, it takes longer for the temp in the library to go up in the morning, meaning they've been trying to 'speed things up' by setting the thermostat higher than needed. The temperature then overshoots. They have since learned they should set it for the temperature they want and to leave it there. (BTW, this is not a problem unique to geothermal, but to radiant heating, regardless of the heat source.)

Third, the geothermal system will be using fan coils not all that different from those presently used, but they will be ducted into the various zones (the ducts don't run the length and breadth of the building). Each duct services one fan-coil, each services one room or area. This is not a central forced hot air/cooling system. It is more accurately a hydronic air system.

Upstairs will have 13 heating/cooling zones. Downstairs will have 9. Heating or cooling water will only be directed to the zone calling for it, not to all zones much like the present system.

For more comprehensive look at geothermal, go to the FPC website.

There are links to articles covering the concept, a presentation by Water Energy (a geothermal engineering firm) as well as a chart showing the heating/cooling cost differences between geothermal and conventional systems (oil, natural gas, propane, electric)

Read them yourself and make up your own mind.

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