Author Topic: Geothermal Heat  (Read 14116 times)

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jenkinswt

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Geothermal Heat
« on: January 22, 2011, 01:54:42 PM »
Not sure if anyone over here has read my wind to heat post but I wanted to learn some about geothermal systems. I have been doing some reading and have found some DIY stuff but not any installation writeups. Anyone here install their own? I worked on a job a few years back and it was a new house. The guy had geo put in. I didn't see it installed but he said it was a bunch of loops in the ground, not sure how deep. I have also read about holes being drilled. I am looking to heat about 2,000 square feet that is highly insulated and it can get down to -20 or colder.

If anyone has installed their own I would love to hear about it or even if you had it done to your place if you have any details, cost of using the heat, etc. This guy had some different kind of meter put in when his was installed, not sure what that was about. If it was an option for me I would want to keep it pretty basic and use a windmill to provide electricity down the road. I have heard it works just the opposite of a air conditioner, in fact I found a thing last night where people were putting air conditioners in backwards, sounded kinda rigged to me but they claimed it was heating a garage. It sounds like the ground is pretty efficient if you can get 55 degree ground temps.

Still looking at all my options and my backup heat will be wood.

zap

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Re: Geothermal Heat
« Reply #1 on: January 22, 2011, 04:51:19 PM »
A story on a foam house using a ground source heat pump... i.e. geothermal.

jenkinswt

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Re: Geothermal Heat
« Reply #2 on: January 22, 2011, 05:12:41 PM »
I'll have to look at that more, the house looks impressive. I found a site, ricksgeo.com and I am getting pretty interested in geo. It has alot of details but haven't finished reading to decide whether or not I could install it or not.

I have a big enough area that I think I could just rent a backhoe for a week and do loops. It sounds like you definitely don't want to put too big of a pump on because they are more efficient to run longer periods than to start up and shut down alot. So my current thinking of build it bigger probably won't work in this department. 

zap

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Re: Geothermal Heat
« Reply #3 on: January 22, 2011, 10:38:57 PM »
After we finished that house my brother-in-law went to school for geothermal.  He has a few systems under his belt now and I think everyone has been trench.
If you're half way proficient on a backhoe it should be no problem and depending on the situation, even the slinky method in a pit will work.

The 'art' of the install seems to be the ability to fine tune the system once it's running.

jenkinswt

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Re: Geothermal Heat
« Reply #4 on: January 22, 2011, 11:10:42 PM »
I have used a backhoe quite a bit. I am looking into a little bit of everything right now as far as heating options and trying to weigh it all out. I have always burned wood and used to that but where I am moving I will have to look around for the wood, where as now I look out my window and all I see is trees.

thirteen

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Re: Geothermal Heat
« Reply #5 on: January 23, 2011, 08:24:18 AM »
My soninlaw built his basement out of foam blocks and put a ground heat system in. His house is large around 3800 ft. They made the basement out of block but had a prefab put on top. He wishes he would have made the whole house out of foam blocks. He also wishes he only made on level not two. But ego said he needed more room. His heating system was put on a separate elec. meter. He is planning to install a solar system in about two years and wanted the heat system to have a different meter so he could monitor the usage.  So far it costs him about $45.oo per month to heat and cool his house. He was going to use propane to heat his house until he read about this underground system. For his house he would be running about 3-350 per month for propane. So he thinks he has a good deal. The cost of the heating / air conditioning system was around $19,500.oo so it will pay for it's self in about 5 years with the savings averaging about $3-400 per month. 
His neighbor used his trackhoe and dug 8 ft wide trenches 6-8 ft deep. They told him the it had to be compacted when he got next to the house to allow for possible soil shifting. He has mostly sandy soil to work with but where he had rock we put sand down and compacted it before thepiping was put down in the trenches and once the guy from the heat system gave us the OK we covered it up. It works very nicely keeping the house around 70. The solar system he needs will be $$ but when he gets old it will have paid for its self.
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GaryGary

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Re: Geothermal Heat
« Reply #6 on: January 25, 2011, 10:50:12 PM »
Hi,
There are some good links with pretty good hands-on design information here:
http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm#GSHP

Just from reading posts of people who have had geothermal heat pump systems put in, there are a lot of ways to do it wrong.  Getting the size of the buried tube field right seems to be the most common problem.

I'd compare the cost of a program to upgrade your insulation, sealing, windows, ... to a heat pump package that will save the same amount of energy -- insulation never needs a new compressor :)


Gary

ghurd

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Re: Geothermal Heat
« Reply #7 on: January 26, 2011, 09:49:25 AM »
Either a bit of an RE twist or a crazy idea.
Gary will have to decide.

Places in the US south west use geothermal for A/C.  It raised the ground temperatures in some areas.

Here, and anywhere it gets down to -20, A/C is probably a low priority except for a couple weeks a year?  More worried about heat.

If doing all that digging anyway, why not trench a few strips 3' deeper, lay in some cheap black plastic pipe.
A small cheap solar drain back system to heat water starting in maybe mid June, and run it through the deeper pipes to raise the localized ground temperature.
It would not take much cost or complexity to move a whole lot of summer BTUs down there into storage for winter use.

I would think it could increase the ground temp considerably, thus increasing the heating efficiency.
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DamonHD

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Re: Geothermal Heat
« Reply #8 on: January 26, 2011, 09:58:24 AM »
G: that sort of scheme *has* to be used to replenish ground heat in densely-packed urban areas, ie where the is little outside ground space for each heated sqft inside.  All it does is get heat into the underground thermal store quicker than it otherwise would.

It's also a good heat dump for an oversized solar thermal system in summer to avoid boiling the water too much...

Rgds

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jenkinswt

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Re: Geothermal Heat
« Reply #9 on: January 26, 2011, 10:41:11 AM »
Yeah I am not so worried about ac as I am heat. I think for now I have scratched most of my ideas off the list. I have 5 acres of ground that is under tillage by a farmer. He grows corn/beans on it. I am going to put in a corn furnace as well as really insulate the house. The furnace I am looking at will burn just about anything corn, pellets, soybeans, can't remember it all. I already have a grain bin so I am going to store up the corn there and use it through the winter. If I wanted I could even get a pellet maker and make pellets out of a lot of stuff including grass but for now I am only looking at corn. I need between 190-235 bushels approx to get through the winter but hope to have at least 300 bushels stocked up or more. The ground should produce around 150 bushels but could produce alot more. I will be farming it myself. I know the whole corn growing is touchy for some people but the way I look at it I will be getting renewable heat right from home, leftover stuff to feed chickens which will help feed us. Also I will be growing sweet corn to sell along with other produce so I will have corn to eat as well as a wide array of other things. I figure the first year will be transitional but next year I will grow even more stuff. I have grown a fair amount of corn before but this will be the most I have done.

At some point I want to grow all of this as organic as possible and will be looking into that. I know this is extremely different than geothermal but that is where I ended up with my thinking. Thanks everyone with the geothermal research anyways.

ghurd

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Re: Geothermal Heat
« Reply #10 on: January 26, 2011, 01:48:30 PM »
G: that sort of scheme *has* to be used to replenish ground heat in densely-packed urban areas, ie where the is little outside ground space for each heated sqft inside.  All it does is get heat into the underground thermal store quicker than it otherwise would.

They already do it?  I never heard of it being done.
As always, too late to apply for my patent worth dozens of dollars.  :'(
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zap

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Re: Geothermal Heat
« Reply #11 on: January 26, 2011, 02:52:00 PM »
Much the same as harvesting ice for summer use, you can go the opposite direction of storing heat.

http://news.cnet.com/Ice-powered-air-conditioner-could-cut-costs/2100-1008_3-6101045.html

I remember this idea being discussed back in the 70's in Popular Mechanics/Science.

GaryGary

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Re: Geothermal Heat
« Reply #12 on: January 26, 2011, 02:58:58 PM »
Either a bit of an RE twist or a crazy idea.
Gary will have to decide.

Places in the US south west use geothermal for A/C.  It raised the ground temperatures in some areas.

Here, and anywhere it gets down to -20, A/C is probably a low priority except for a couple weeks a year?  More worried about heat.

If doing all that digging anyway, why not trench a few strips 3' deeper, lay in some cheap black plastic pipe.
A small cheap solar drain back system to heat water starting in maybe mid June, and run it through the deeper pipes to raise the localized ground temperature.
It would not take much cost or complexity to move a whole lot of summer BTUs down there into storage for winter use.

I would think it could increase the ground temp considerably, thus increasing the heating efficiency.
G-


Hey Glen,
That seems like a sensible idea to me.
We were looking at a new home for sale here in Bozeman the other day.  It has a big geothermal field, and solar collectors.  The builder was there and we talked about doing just what you mention.  I offered to help with the numbers, but have not heard back from him as yet.  He seemed very interested in the idea (which he had already thought of himself independently) -- he liked the idea that very little extra cost is involved.

Heard another interesting idea for in ground heat stores.
The idea would be to basically enclose a fairly large chunk of earth in an insulation "umbrella"  (a bit like the PAHS homes).  You would normally think about doing this by digging up a good sized area, installing the poly pipes to add and remove heat, then insulating the sides as you backfill, and putting an insulation lid on then more backfill.  Lots of digging a labor and mess.
This persons idea was to not disturb the earth that is used for storage.   He wanted to install the poly tubes with one of the gadgets that kind of plows them through -- a heavy vehicle basically pulls the pipes through behind a blade that penetrates the earth.  
Then dig a narrow trench around the periphery and insulate it -- this might be done with a heavy duty trencher.  Then install insulation over top -- presumably with a layer of dirt and grass over it.
This would be heated with solar collectors starting some time in the summer.  
Heat would be extracted in the winter and distributed to (say) a radiant floor in the house.

Seems like two things tend to make seasonal heat storage tough to do successfully.  First is the relatively high heat losses of homes -- even new ones built to code -- you need something that is well on the road to a Passive House Institute level of insulation to have  a chance to store enough heat in the summer.  The other thing is the cost of putting in the very large storage -- which your idea and the other idea might address.

Its not easy even with a well insulated home:
http://www.builditsolar.com/Projects/SolarHomes/SandBed/RamlowSandbed.htm

But, your thought on adding heat to a geothermal field that is already there is really cheap to implement, and cheap to run -- just a circulating pump.

In the same general area, the Drakes Landing folks seem to be doing pretty well with their project:
http://www.dlsc.ca/
They are predicting being up to a 90% solar fraction soon.

Gary



« Last Edit: January 26, 2011, 03:01:23 PM by GaryGary »

DamonHD

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Re: Geothermal Heat
« Reply #13 on: January 26, 2011, 03:29:59 PM »
GH: Yes, I think it's already being done at at least one site in Germany and Canada.

Start here for a bit more: http://www.inference.phy.cam.ac.uk/withouthotair/c21/page_152.shtml

I've considered such as scheme myself, but we may have moving groundwater which would make 'storage' hard.

Rgds

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ghurd

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Re: Geothermal Heat
« Reply #14 on: January 26, 2011, 03:38:05 PM »
Since it is not a crazy idea, I'll add some more info about it already working in some crazy cold place.

I helped an overseas serviceman do a few projects, which led to other talk.
His folks live someplace that gets evily cold, like MT or ID or similar.  They have some greenhouses.  We talked some, they trenched some poly pipe down 4~5', heat collector was pipes in the greenhouse when it was hot and nothing like a proper panel, and a pump in a tiny drainback system (memory is... uh... I forgot what I was gonna say).
It increased the season by 6 weeks, IIRC.

If basically a pump, some pipe, 35/55 gallon tank, and a giant plastic bag with tomato plants in it can do that, it seems like it would be a great idea to add to a geothermal system to me.

I don't see why any serious hard numbers need run.
As long as the water coming out of the ground is cooler than the water going in, then its a gain.  ?
Gosh.  The thing would even move heat on a warm summer night!

A preheater of a muffin fan and car heater core could help too, sometimes.  LOL
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GaryGary

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Re: Geothermal Heat
« Reply #15 on: January 26, 2011, 08:37:22 PM »
Since it is not a crazy idea, I'll add some more info about it already working in some crazy cold place.

I helped an overseas serviceman do a few projects, which led to other talk.
His folks live someplace that gets evily cold, like MT or ID or similar.  They have some greenhouses.  We talked some, they trenched some poly pipe down 4~5', heat collector was pipes in the greenhouse when it was hot and nothing like a proper panel, and a pump in a tiny drainback system (memory is... uh... I forgot what I was gonna say).
It increased the season by 6 weeks, IIRC.

If basically a pump, some pipe, 35/55 gallon tank, and a giant plastic bag with tomato plants in it can do that, it seems like it would be a great idea to add to a geothermal system to me.

I don't see why any serious hard numbers need run.
As long as the water coming out of the ground is cooler than the water going in, then its a gain.  ?
Gosh.  The thing would even move heat on a warm summer night!

A preheater of a muffin fan and car heater core could help too, sometimes.  LOL
G-

Hi,
I guess by numbers I just meant a rough idea if:

1- it offers a descent payback on the dollars you put into doing it.  Seems like for the one you were proposing it would almost have to given that the cost of the added solar collectors and circulator is pretty small.

2- does a reasonable size system of this kind store enough heat to meet a worthwhile fraction of the total winter heat load.  In other words can you put enough heat in that ground store to really make any worthwhile difference once winter starts. This is something I'm really curious about. 
I talked with the builder I mentioned above about adding some simple ground and ground loop fluid temperature logging that would at least get some handle on how much heat the solar was able to add, how fast that heat gets lost to the surrounding soil, and how much warmer water the GSHP would see through the winter.  His setup was ideal for this in that he had two separate geothermal fields and was only thinking about adding the solar heat to one of them.

Gary

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Re: Geothermal Heat
« Reply #16 on: January 27, 2011, 03:25:34 AM »
I think there's a slight difference between 'ground heat' and 'geothermal heat'...
Geothermal heat are more or less directly heated by either volcanic activity further down, or natural radioactive reactions in the ground. One example are where water are pumped down some km's, and steam comes up that drives steam turbines.

Ground Heat pumps utilitize the heat in the upper layers of the ground that has been stored by the sun during summer, and/or if one hits the water level, one has a more constant source of stable heat, since the water where one collecs the heat from, are always replenished with water with constant temp...

Just my 2c... ;)
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artv

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Re: Geothermal Heat
« Reply #17 on: February 09, 2011, 08:38:23 PM »
HI All ,...I have an artisene well on my property,...and no matter how cold it gets ,that water never stops coming out of the ground. Is there not some way to re-coop this excess heat??...At -40 if that water is still running , it has to have stored energy in it..........any ideas would be greatly appreciated.........artv

DamonHD

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Re: Geothermal Heat
« Reply #18 on: February 10, 2011, 01:55:53 AM »
The problem is that the maximum you can extract from it is determined by the so called Carnot limit, which is roughly proportional to the difference in the hottest and coldest places that you have available divided by the temperature of the coldest *in Kelvin*.

What that means in practice is that you can probably extract only much less than 1% of the energy available for the sorts of temperatures that you are describing, and unless that well is flowing very fast then there isn't much energy to start with.

Rgds

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Kwazai

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Re: Geothermal Heat
« Reply #19 on: February 10, 2011, 07:26:16 AM »
not sure if these would be of interest to you or not.
This one is the best of their series- but its a little small to do much with (showers maybe..)

http://www.motherearthnews.com/Renewable-Energy/1981-07-01/DIY-Water-Heating-Compost.aspx

More recent players...

http://www.youtube.com/watch?v=X6OlbEgP35U&feature=related


if you actually track down the Jean Paine info- he was building compost piles in the 100s of tons range to supply fuel for the house and car (2500+ gallon tank inside a 30 foot+ tall pile or so of compost).

its a good read ;though, little of it is numbers oriented- just generalities (fine sawdust, etc...)

L8r
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WindriderNM

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Re: Geothermal Heat
« Reply #20 on: February 24, 2011, 09:01:37 PM »
I have driven a 2in sand point well 23ft deep the water level is at about 12 to 15ft at a temp of about 100 deg. F. There is a steep bank down to a river the water level of the river is within a few ft of the water in the well. would it be feasible  to use this to heat my house? I would like to use a solar powered pump to pump the water from the well through the house then dump it in the river.
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zap

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Re: Geothermal Heat
« Reply #21 on: February 25, 2011, 11:52:06 AM »
It's quite feasible especially with 100°F water.

Some of the things to consider:
  • The amount of flow you can get from your well and still maintain the 100°F temperature.
  • The power required to pump the water the 12-15ft height of the well plus the elevation/distance to your house.
  • The amount of mineralization of the water and how much of it will precipitate out once cooled down.
  • Any laws or regulations in your area for proceeding with such an endeavor.

If the the river has enough flow you might be able to use it instead of solar for pumping... once again, if that's allowed in your area.

12AX7

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Re: Geothermal Heat
« Reply #22 on: February 25, 2011, 08:43:17 PM »
There is also the issue of where the water is dumped after being processed by the heat pump.

At 100deg..   I wonder if you could run it though a heat exchanger and not use a heat pump?

WindriderNM

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Re: Geothermal Heat
« Reply #23 on: February 25, 2011, 09:13:43 PM »
The water discharge will be about the same elevation as the water level in the well so probably won't need a very powerfull pump.
It was able to fill a large hot tube in about 3 hrs with no decrease in temp.
There shouldn't be any legal problems as there are several dozen well fed hot tubes that discharge into the river in the area.
I drove a 1/2in  pipe down 25ft deep by putting a hose on it and forcing water through it on another part on the property. the water temp there is 105 deg f. the water  level is about the same.
I am thinking about radiant floor heating.
        
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WindriderNM

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Re: Geothermal Heat
« Reply #24 on: February 25, 2011, 09:16:27 PM »
I wasn't going to use a heat pump
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MattM

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Re: Geothermal Heat
« Reply #25 on: February 26, 2011, 07:11:20 AM »
That is one substantial heat source.  You shouldn't have any problems heating your whole house on water that warm.   

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Re: Geothermal Heat
« Reply #26 on: August 12, 2014, 08:25:24 PM »
this is an old post.  I have heated with geothermal since 1985 and would not consider anything else. I started a business in 1987 and sold and installed over 250 systems before selling the business in 1991.   With a properly designed hydronic heating system you can heat your home with 80 degree water.  Yup I said 80 degree water, even in Wisconsin when it is 30 below.    105 is a no brainer.   

Bruce S

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Re: Geothermal Heat
« Reply #27 on: August 13, 2014, 08:56:39 AM »
With winter just around the corner, maybe you could start a new thread with some "quick tips" that people might not think of?
With this Aug already showing signs of being one of the cooler ones on record for Missouri; I've already started stacking the firewood and extra insulation around exterior that I wouldn't normally even worry about.
A new thread would be nice explaining some thing people looking at geothermal heat might not think of; would be a very good start.
Cheers
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Mary B

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Re: Geothermal Heat
« Reply #28 on: August 13, 2014, 06:16:58 PM »
I am starting to stockpile pellets for the pellet/corn stove. have 1 ton in storage so far. 5 more tons to go...

Bruce S

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Re: Geothermal Heat
« Reply #29 on: August 18, 2014, 02:54:47 PM »
It's just now August and even here in Missouri we're starting to see the signs of a hard hard winter, so even my standard stockpile of seasoned wood is now 1/2 again large with more on the way.
Along with adding newer insulation in the attic, we should be almost ready.
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