Looking at possible geothermal heating/cooling/hot water system

Today I just spent a good amount of time without success attempting to fix a wall-mounted AC which was dripping water into the room. Earlier this year the one in my bedroom had a similar issue. Bottom line-I'm disgusted with the maintenance and costs associated with individual room air conditioners in the summer and oil heat in the winter. The same boiler we use for heating also makes our hot water. The boiler and oil tank take up a huge amount of space which I could definitely put to better use. I'm looking to replace everything with a geothermal system with the following characteristics:

1) Several zones, preferably one for each room, or at least one in the three or four rooms we use the most.

2) Heating in winter, cooling in summer.

3) Hot water all year round.

4) Hopefully no need to install air ducts (in other words, a split system).

5) Possible variable speed compressor which adjusts its output to match demand.

I'd like some help first of all with what to expect for estimated installation costs, possible tax credits, and so forth. My estimate is we'll need at most about 50,000 BTU of cooling, and probably an equal amount of heating, but most of the time we probably will only be using 1/3 to 1/2 of that. The second thing would be any suggestions of who might do this type of installation in New York City. Also, are there any permit fees which might make the entire idea a nonstarter? My boiler repair guy said NYC charges $100,000 for a permit to install a geothermal system but he might have been told to say that by his company.

As for when we'll be doing this, it could be any time between this fall and a few years from now. Our boiler is as old as the house ( 60 years ). While it's still working OK, I don't want to wait for it to fail and then have to rush into things.

Newyork, that's a whole different ball of wax than here. I've seen advertisements, and talked to people who prices it out up here in Alberta, and its just a no go up here. 40-80grand and the few people I know that have had it done, the vertical pipes where too close together, and they'd get freeze ups. Might be cheaper where you are, with the warmer climate.

dont you need to dig a deep hole for geothermal cooling pipes? how to do that in NYC?

TedTheLed said:

dont you need to dig a deep hole for geothermal cooling pipes? how to do that in NYC?

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The hole could be in the back yard. I'm 100% sure there are no utility lines running underneath the back yard. The utility lines usually run in the street and then under the sidewalk/front yard to get to each house.

I looked this stuff up a while back and you'll really have to do the exercise -- you need to find out what's being done in your area, using what kind of equipment, for your particular location. Do you have a driveway giving access to the back yard so you can bring in either trenching or drilling equipment? Who's nearby who does the work? The first few dozen hits with this Google search should help:
"geothermal+heat"+"new+york"

Take a lot of time, you don't want someone to come in who will just throw a roll of plastic pipe in a ditch and bury it (if the pipes overlap they don't effectively transfer heat; settling makes some kinds of pipe kink, or break, where after eventual settling they bend over one another; depending on where the eventual spillage and leakage will spread to, some sites are going to be OK using antifreeze, others will use clean water in the system with protection against freezing.

Some trench, others drill vertically. If there's limestone with a cave system down there, you don't want to do it at all (some midwest sides did make that mistake).

I really want to do this -- in several different places where family members live -- and have looked into each location and none of them are yet ready for people with little homeowner projects. Big estates or businesses or schools/libraries/etc. are at the scale currently getting this kind of thing easily.

I really hope your site works out and you document it as it goes along.

im under the impression geo cooling is a very basic thing, basically it is 'throwing a bunch of pipes a few feet underground' .. and you can go laterally if you cannot go deep. deeper is colder so you need less pipe is all. and when I was looking at it, there could be no leakage as only air was in the pipe.. of course the codes will probably dictate exactly what and how you will do it. Id use sched 40 pipe if I were worried about breakage, but codes prob wouldnt allow it..

Gotta say, I dont understand this it all! I thought geothermal electricity and hot water was only possible where there is natural geothermal activity, like near a hot springs or volcano or something. You'd use that heat to produce steam and electricity.

How does the 60 degree F temperature of the ground produce electricity? How does it produce enough heat in winter to bring your indoor temps up to 72 degrees F? I dont get it......

no mystery; underground air pipes are for cooling only..

TedTheLed said:

only air was in the pipe.. of course the codes will probably dictate exactly what and how you will do it. Id use sched 40 pipe if I were worried about breakage, but codes prob wouldnt allow it..

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PVC isn't very thermally-conductive - nor is air. There are buildings structured with airflow through basements to cool air in summer, but I think pipes would get condensation issues. Mold! Eugh!

HighlanderNorth said:

Gotta say, I dont understand this it all! I thought geothermal electricity and hot water was only possible where there is natural geothermal activity, like near a hot springs or volcano or something. You'd use that heat to produce steam and electricity.

How does the 60 degree F temperature of the ground produce electricity? How does it produce enough heat in winter to bring your indoor temps up to 72 degrees F? I dont get it......

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My understanding is that home geothermal heat/cooling systems these days provide an improved heatsink for a heat pump. Underground it's a pretty constant temperature year-round (And above freezing if you're deep enough!). A heat pump in summer tries to put more heat outside (AC) and in winter will try to suck heat from freezing air. If you put their radiator underground, heat pumps have a lower temperature-difference to work against. Most temperature-difference generation systems want a larger difference between heat and cold.

AnAppleSnail said:

My understanding is that home geothermal heat/cooling systems these days provide an improved heatsink for a heat pump. Underground it's a pretty constant temperature year-round (And above freezing if you're deep enough!). A heat pump in summer tries to put more heat outside (AC) and in winter will try to suck heat from freezing air. If you put their radiator underground, heat pumps have a lower temperature-difference to work against. Most temperature-difference generation systems want a larger difference between heat and cold.

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That's exactly the purpose-to reduce the temperature differential the heat pump is working against. Going to basic thermodyamics, the COP (coefficient of performance) of a heat pump is Th/(Th-Tc) for heating and Tc/(Th-Tc) for cooling. Temperatures are in kelvin. In both cases note that the less the difference between the hot and cold sides, the larger the COP, and the less power you use for any given output. Also note that in practice the temperature differential will be larger than the temperature differential between the ground and the indoor air because heat exhangers require a temperature difference to transfer heat. This could add another 10 to 20 degrees C to the temperature differential, depending upon design.

jtr1962 said:

I'm 100% sure there are no utility lines running underneath the back yard.

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You've gotta' call these guys anyhow:

http://www.digsafelynewyork.com/

Your area has infrastructure going back into the 1600's. No telling what goodies might be down here. I think it's free.

The boiler repair guy said NYC charges $100,000 for a permit to install a geothermal system but he might have been told to say that by his company.

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If true, this would eliminate all small private systems, since the permit would cost as much as the whole rest of the system.

You might want to check in with NYSERDA, see if they can support you in some way.

TedTheLed said:

dont you need to dig a deep hole for geothermal cooling pipes?

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It can be two holes - the equivalent of two wells, or a large shallow area.

TedTheLed said:

how to do that (dig a deep hole) in NYC?

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The call-before-you-dig guys mark out where stuff is. They paint it right on the ground. Then you dig around it.

HighlanderNorth:
Gotta say, I dont understand this it all! I thought geothermal electricity and hot water was only possible where there is natural geothermal activity, like near a hot springs or volcano or something. You'd use that heat to produce steam and electricity.

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That's what they do in places like Iceland or Yellowstone, where there's a *lot* of heat near the surface. In his situation, he will not be producing electricity. jtr is after something much more modest.

HighlanderNorth:
How does the 60 degree F temperature of the ground produce electricity? How does it produce enough heat in winter to bring your indoor temps up to 72 degrees F? I dont get it......

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He will have a heat exchanger out in his back yard. It will put heat in or out of the ground depending on the season. It can pull heat out of what we consider cool or cold water. It will work better pulling heat out of 55 degree ground water rather than 10 degree winter air. Also, with the twin well system you can pull heat out of the hot summer air and store it in your hot well, then pull it back out in the winter when you need it. In winter you can pull cold out of the air* and store it in the cold well 'till summer rolls around.


*For those who are technically minded, I am aware that "pull cold out of the air" is not the most technically accurate way to describe this, but I think it will do for our conversation

Well if you can dig a deep hole in NYC you will be able to hit water probably. very cold water.. for air cooling. air conditioning really, since it would be around 50f or < and so would condense the humidity in the house...and small diameter plastic pipe would suffice.