Taking it down a peg

Eli's guys arrived on the heels of SCPB's guys checking out. Although we had put in a well down to 140 feet for water, we need to take it down to 540 feet, according to Eli, in order to tap the geothermal energy for our heating system.

What's geothermal energy? Like my friend Roger says, it's cave man thinking. Inside a cave, the constant temperature is approximately 55 degrees. Sounds warm on an icy New England winter day, and cool on a blistering humid August one. All we're doing is bringing up water at a constant 55 degrees, adjusting the heat with a heat exchanger to one comfortable to us, and in that way reducing the energy it takes to heat or cool. It's much easier to heat 55 degrees to, say, 70 degrees than it is to heat 1 degree. Similarly, it's easier to cool the same way. When you have geothermal energy, you have both heating and air conditioning at a very modest carrying cost.

We are installing a standing well open loop geothermal system with a 5 ton air system. There are many types of geothermal systems; this was the one we could afford since we already needed a well (to see previous posts on this subject, click on "HVAC"). For this system, we don't get radiant heat (that involves plumbing the floors), but we do get air conditioning.

Closed loop, open loop…

The cost of geothermal varies greatly depending upon whether you plan to plumb your house for radiant heat or use a simple air system with ducts. The way we’re leaning now is to build an open loop, one hole geothermal system (which you can only do if your water quality is Fabulous) which works by digging our water well deeper (to 500 feet). Then, the system drains at the bottom of the hole, while our drinking water is supplied from a depth of 140 feet and ne’er the twain shall meet, I hope.

Using one of the two name brands (ClimateMaster or Water Furnace), we then limit our cost for the geothermal to the well (ours is costing around 8500k including water well for 5000 which we had to get anyway), plus a backup dry well (leaching field), and the interior machinery and ductwork, which goes for about $5000-5500 per ton. In our two story, cathedral ceilinged 2800 sq ft house, we need to move 5 tons of air.

Generally speaking, a standard forced hot air heating system here costs about 15,000. This means the geothermal is roughly double that. However, you won’t be buying fuel every year, so up here in New England that means it pays back at around 2000 a year, net of the increased electric.

Ah, HVAC systems...

While waiting to find out how much geothermal really is, we’re now looking at the Freewatt™ from Climate Energy (www.climate-energy.com), a micro combined heat and power (Micro CHP) system. You start with a high-efficiency propane furnace with appropriate ducting. Then, you add on another piece—a generator that produces power. Sure, not too much (like 1.6 kilowatts) but it’s going in the right direction. (More information on this technology at www.epa.gov/cppd/climatechoice/technology.htm)
The furnace part is around $5,000, then the generator part is more, about $11,000. Plus the ducting, I’m sure. And you won’t have AC, but with an SIP-built home like ours you will have a whole-house fan somewhere, which mostly does the trick up here in New England. And jeez, you can’t have everything, can you?
So we start with the furnace, and maybe next year can graduate to the generator. Since we have no natural gas, just propane, none of the systems is picture perfect.
One thing’s for sure, I’m learning more about HVAC than I ever really wanted to know. Construction financing is next. Can’t wait.