Re: Liveable temp/ geothermal
From: Sharon Villines (
Date: Fri, 25 Jan 2008 08:22:03 -0800 (PST)
I would love to get more information on Takoma Village's geothermal set up
(and any one else who has geothermal).

Our set up was very bad. Done by a bad contractor who went bankrupt and was actually arrested on our property before installation was completed. (The developer apparently took the lowest bid.) Be sure to use a company that has been in business for a few years at least and receives good recommendations.

A geothermal unit, for those who don't know, uses plastic loops filled with water that go deep into the ground in holes that are called "wells." The water circulates to HVAC units in individual homes. The circulation of the water is done by a pump on the side of the HVAC unit. The circulation needs to be adjusted so the water stays in the ground long enough to reach ground temperature. The water in our systems is about 65 degrees. Thus the HVAC unit only has to heat from 65 degrees and not the air temperature. In the summer, it just cools although there is freon and a compressor -- not sure why. It also has a back up heater in case it is very cold out. Some of our homes have disconnected theirs so their units just get colder instead of triggering the back up.

Geothermal apparently only works in certain geographic areas but I'm not sure which, and I'm not sure of that information either. It came from an installer who did not know what he was doing else wise.

In our system, we have an individual well for each unit. This is apparently not a good design because it means when a loop begins leaking deep in the ground, that well fails. If it is a leaking in the horizontal loop that goes from the home to the well it can be fixed in various ways. Some of our wells have failed and we have had to put two units on one loop.

A better design, and the one used at Eastern Village, is to use a "manifold" that connects all the wells. It is essentially a big circular horizontal loop with various switches that control and redirect the water. (Sorry if these are not the correct names but you get the idea.) With this design when a well fails, all the units still get water. If enough of them fail, you eventually have to dig more wells but you at least have some service while you dig. The HVAC unit does not work without water. A well in DC costs $6,000 to dig. When we dig we will dig three to have back up.

We are currently installing a manifold in the commonhouse basement because two wells have failed to that building. But our consultant says we had too many wells to start with so with a manifold we are fine. He is also recommending that we dig up the green and install a manifold but we are not likely to do that unless wells fail there. He recommends that at the same time we build a partially underground storage facility or something because the earth will already be removed.

Our looper, Lester the Looper, says the loops he has seen fail are all factory sealed loops. He recommends that the loops be built by a looper. But now I think there are continuous loops so they shouldn't leak. The loops are sunk in a hole that is then filled with something -- I think gravel -- so theoretically they could be more easily dug out and a new loop sunk.

The best geothermal units are Water Furnace. We have Florida Heat Pumps which are sort of good, we are told. Braun has just bought the company so it will be easier to get parts and the quality will probably improve.

Water Furnace has several features that are desirable. One is that the unit turns off when the condenser drain pipe clogs. We have had water dripping through several ceilings because there is no way to know the pipe is clogged unless you look inside the closet -- which few of us do. Water Furnace also makes a unit that is almost silent. When the unit is in your apartment, this is important.

Our large 3-4 bedroom units have an additional "super heater" that uses the loops to heat their household water so the water heater is only working from 65 degrees rather than the temperature of city water which can be cold in the winter.

More than you wanted to know about geothermal but it really is wonderful not to worry about heating and cooling bills. My bill for a two bedroom unit with windows on three sides, facing south, used to never be above $45. Recently the rates have gone up so in the coldest months, they are $85. I keep the winter temp at 70, but the sun heats it during the day, and summer temps at 74. One of our members in a one bedroom unit exposed on only two sides who never uses her dishwasher and doesn't have a W/D says her bill has gone up to a high of $18 from $9.

Geothermal is also a more constant temperature. The compressor is designed to work for short periods of time so it works best if the temperature doesn't vary more than two degrees. I have mine set for 1 degree.

It is forced air heating and cooling, which I like because I use a filter that cleans the air instead of having a separate air cleaner. (I have mild allergies.) I leave the fan on all the time. Some people do not like forced air.

All this I learned from a consultant in heating and cooling system design and the physical engineer with our maintenance company.

Sharon Villines
Takoma Village Cohousing,Washington DC

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