Geo thermal from a well is it possible ????????????
Geo thermal from a well is it possible ????????????
I have a well on my French property It must be at least 50 or 60 feet deep, I was told by a freind that all I had to do was chuck a coil of pipe down it connect that to a commpessor, and Bobs yer uncle free hot water.I know that nothing is ever that simple but could somebody tell me if the idea is even feasable.......sorry to be such a know nothing twit ,but we all have to start somewhere.......Colin
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Martin
- A selfsufficientish Regular
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- Location: Nr Heathfield, East Sussex
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yes and no................ 
It ain't "free", but you do effectively "get something for nothing" with lots of caveats...........
What you are describing is actually a "ground source heat pump", which is in essence a blessed great fridge running backwards...........if you pump water through coiled pipes buried in the ground (or in your case, chucked down the well), and circulate it through the heat pump, you can indeed remove some of the heat from the surrounding earth (or well water)
BUT, and here start the caveats - to do so, you need one heck of a lot of pipe buried (or submerged), and to heat even a small house, you'd need a terrific amount of heat transfer pipes, far more than would easily fit down a well.......and then there's the biggies - even if you have a really efficient heat pump, with loads of heat transfer pipe, the output from the heat pump is "low grade heat" (at relatively low temperature), and is really only suited to underfloor heating..................last but not least, you may be getting 3 "free" units of heat from the heat pump for every unit fed in, but the energy you have to supply to the superannuated 'fridge is the highest grade, and most expensive energy of all - electricity..........so it's usually not worthwhile, unless it's a new build, and you are also generating your own electricity.........
If you want domestic hot water, look at solar hot water for the spring- autumn season, and woodstove/backboiler for winter - both are loads more cost-effective, relatively low tech, and affordable!
It ain't "free", but you do effectively "get something for nothing" with lots of caveats...........
What you are describing is actually a "ground source heat pump", which is in essence a blessed great fridge running backwards...........if you pump water through coiled pipes buried in the ground (or in your case, chucked down the well), and circulate it through the heat pump, you can indeed remove some of the heat from the surrounding earth (or well water)
BUT, and here start the caveats - to do so, you need one heck of a lot of pipe buried (or submerged), and to heat even a small house, you'd need a terrific amount of heat transfer pipes, far more than would easily fit down a well.......and then there's the biggies - even if you have a really efficient heat pump, with loads of heat transfer pipe, the output from the heat pump is "low grade heat" (at relatively low temperature), and is really only suited to underfloor heating..................last but not least, you may be getting 3 "free" units of heat from the heat pump for every unit fed in, but the energy you have to supply to the superannuated 'fridge is the highest grade, and most expensive energy of all - electricity..........so it's usually not worthwhile, unless it's a new build, and you are also generating your own electricity.........
If you want domestic hot water, look at solar hot water for the spring- autumn season, and woodstove/backboiler for winter - both are loads more cost-effective, relatively low tech, and affordable!
http://solarwind.org.uk - a small company in Sussex sourcing, supplying, and fitting alternative energy products.
Amateurs encouraged - very keen prices and friendly helpful service!
Amateurs encouraged - very keen prices and friendly helpful service!
Big thank you
that was great, just what we joined this forum for,a sensible common sense answer.It looks like I will be doing exactly as you said with log burners for winter. Now I just have to look into the cost and praticability of solar panels for the summer. I saw a report on this forum somewhere about using old radiators,I will go back and find it ....Thanks again.............Colin
Re: Geo thermal from a well is it possible ????????????
This system of "stealing " some of the Earth's heat is used extensively here in Sweden but as has been stated, the Real Mcoy would cost an arm and a leg, (and that's just for the 200 meter deep bore-hole, hose and pump) The heat-pump would require further body parts, (and that pump requires "winterizing" if you live in a cold area). I use two wood-burners for heat and a 50 liter milk-churn fitted with a tap sitting on the one in the kitchen for hot water. Great...cheap too!
Re: Geo thermal from a well is it possible ????????????
do not despair too soon.
most ground source heat pumps are fed by pipe work buried about 6 ft below ground level where the ground temp does not change as much as surface temp due to insulating effect of earth above. so during winter on average the temp at this level is 5 deg C above surface. as a rule of thumb 50m of pipe will give about 1 kW of power.
coolant in the pipes gets heated by the 5 deg and goes through a heat pump which chemically magnifies the increase by pressure to around 50 deg C. this is lower than a normal boiler feeding radiators (60 deg). again rule of thumb - double the number/size of rads for good heating or, as said above, use underfloor heating.
the heat pump requires electric to operate but for every one unit of electric power in you can get 4 units of heating power out.
some systems fail to live up to expectation due to the ground being dry. once you have taken heat out of the ground around the pipe it fails to heat up due to poor thermal conductivity of dry soil. wet soil works better as water is good conductor of heat. taking this one step further putting your pipe in water (pond) is very good but you must be at least 12 ft down to get thermal difference between surafce and warmer layers lower down; and have good mass or exchange of water. so if your well has running water in the bottom you could be ok - it will be heated by surrounding rock and this will replenish due to flow. try pumping your well out to determine in flow of water.
depending on diameter of your well you could well be able to get a good contribution to your heating. look at your boiler rating Btus 50,000 Btus is about average; thats roughly 15 kW which requires 750m coil suspended between 15 ft below surface down to the base of your well.
worth a look if you are planning to stay there. best of luck.
most ground source heat pumps are fed by pipe work buried about 6 ft below ground level where the ground temp does not change as much as surface temp due to insulating effect of earth above. so during winter on average the temp at this level is 5 deg C above surface. as a rule of thumb 50m of pipe will give about 1 kW of power.
coolant in the pipes gets heated by the 5 deg and goes through a heat pump which chemically magnifies the increase by pressure to around 50 deg C. this is lower than a normal boiler feeding radiators (60 deg). again rule of thumb - double the number/size of rads for good heating or, as said above, use underfloor heating.
the heat pump requires electric to operate but for every one unit of electric power in you can get 4 units of heating power out.
some systems fail to live up to expectation due to the ground being dry. once you have taken heat out of the ground around the pipe it fails to heat up due to poor thermal conductivity of dry soil. wet soil works better as water is good conductor of heat. taking this one step further putting your pipe in water (pond) is very good but you must be at least 12 ft down to get thermal difference between surafce and warmer layers lower down; and have good mass or exchange of water. so if your well has running water in the bottom you could be ok - it will be heated by surrounding rock and this will replenish due to flow. try pumping your well out to determine in flow of water.
depending on diameter of your well you could well be able to get a good contribution to your heating. look at your boiler rating Btus 50,000 Btus is about average; thats roughly 15 kW which requires 750m coil suspended between 15 ft below surface down to the base of your well.
worth a look if you are planning to stay there. best of luck.