Ground Source Heating

[bookman]

As I live miles from anywhere in europe I was wondering if anyone had come across plans for DIY ground-source heat pumping.  Anyway of getting constant heat in the winter or cooling in the summer would be great.  Apologies if this has been asked before but I have had a good look thru the forum and cant find anything apart from a couple of throw away references.  Many thanks in advance

[Roamer195]

For a ground-source heatpump, you'll either need to bore deep holes in the ground and run heat-echange tubes down them. Or, for undeveloped property, skim off a several feet of topsoil, set all your exchanger tubes into the ground horizontally, then refill the lot with dirt.

Another option would be a solar-assisted heatpump system. You can make individial heat-exchanger panels with 4'x 8' sheets of 1/32" steel. Tack weld a bunch of washers onto the face of one sheet and then tack-weld the second sheet on top of those. The washers are in the middle of the "sandwitch". Then weld a couple of tubing inlet/outlets on opposite corners of one face. Then weld up the outer edges so the two sheets form a sealed hollow space. The washers are spacers to keep the sheets from getting squashed together.

Paint the whole thing flat black and put it on the roof. Then circulate glycol solution through it.

The glycol solution is circulated down from the panel and through the evaporator on the heatpump.

With solar assist, a heatpump can collect up to 12kw of heat for every 1kw used to drive the compressor. That's based on something like the new "eco-refrigerant" R12 replacement, not 134a(toxic, poor refrigerant).

The more panels you put up and connect in series, the larger your collector surface, the more efficient the system becomes.

In the summer-time, drop the panels down into the shade and circulate the glycol through the condenser to dump heat outside.

Hope this helps.

[bookman]

Is it possible at adapt a fridge compressor to run as a ground Source Heatpump?

[finnsawyer]

Probably not a good idea.  A ground source heat pump is a pretty sophisticated (and expensive) machine.  It moves a lot more heat than your typical frig.  They also have built in protection devices.  The one I have also cools and helps heat water.  I'm set up to get the heat from well water.  It's a good way to go if you have a robust water supply (greater than 4 gal per minute).  While you could experiment, it's probably not worth the trouble.

[K3CZ]

Here are a couple of USA websites that are rich with the type of info you are looking for, altho this type of system has not yet matured into DIY, because of the required level of specialized contractor involvement:

           http://www.igshpa.okstate.edu/faqs/general.html

           http://www.igshpa.okstate.edu/geofacts/residential.html

Good luck - GSHP is a very practical and fuel-saving technology.    K3CZ    

[hydrosun]

I think the most important way to utilize renewable energy is to reduce the amount of energy needed.  In other words, insulate, insulate insulate. Onece that is done the amount of heat needed to heat a house is much lower. I live in a earth bermed dome home.  I power it with solar and hydro. This year I've added a small 10,000 btu portable heat pump. It takes 750 watts to run. When the hydro is running over 75 gpm on 100 feet head I can keep the house over 70 degrees  by pulling in outside air and exhausting colder air.  When the temperature goes below freezing this becomes less efficient . But when it gets that cold my stream flow lessens and I don't have the power to run it. So we burn wood for a few hours a day, until it warms up and rains again.  

I do want to modify the heat pump to add a water heat exchanger to be able to pull heat off the water from the hydro stream.  It would flow through underground pipes to the house and be at ground temperatures.

In the past I've used a small compressor from a pop machine to heat the bathroom. I ran water over the cooling coils to pull the heat out of the hydro water. The compressor  was probably less efficient than the heat  pump I use now. I figured I was getting 3 times the heat compared to direct resistant heating.  The heat pump I using now , a Sunpentown WA1010-H is rated at about 5 times the heat (EER 15). But any heat pump is going to produce more heat than direct resistance. I think the important thing is to get a heat pump sized to your system. It doesn't do any good having a heat pump that uses 4 KW electricity if you don't have a system that can run it. A refrigerator compressor will probably take 100 - 300 watts to run. An efficient pump to circulate the water through underground pipes  doesn't take much power. so the only problem is a water to compressor heat exchanger. I plan on using small flexible copper carrying the freon inside 1/2 copper pipe for the water. My brother made  one for our farm years ago to preheat water from the compressor cooling the milk tank. Just a matter of evacuating the freon and cutting and splicing.  Or the cooling coils can be place in a tub of water that is pump out of by the circulating pump. i think this is an excellent way to increase the usefullness of an alternative energy system.

chris

[robotmaker]

In order to take advantage of the earth's constant temperature (approx 55F)you need to either drill wells and do the take water from one and dump it back into the other after running it thru your heat exchanger, in which case you can't use glycol or any other chemicals due to polution of the ground water.....

- OR -

you can do like I did and dig a 6 foot deep trench about 100Feet long and bury 1000 feet of 3/4"PVC pipe in the ground.  Then you can circulate your water with glycol in it with less of a chance of contamination of the ground water.  Of course you want to pressure test all your fittings first too.  This I then ran to my compressor for my heat pump thru a radiator and a small 10 gallon per minute circulation pump.  Since my heat pump won't work very well below 40-45F, this helps with getting heat out of 50-55F water.  In the summer, instead of trying to get cold out of 97 to 104F outside air, it works much better when the temp is 50-55F.. (imagine that)

If you want to see a few pictures of my trench and the pipe, let me know.  Glad to share...

rj

[Geek]

I just put in a ground source heat bump for my 1400 square foot 2 story farm house. It is well insulated and pulls less that 1500 watts blower and pump both running. It gets a little cool here but the syatem is good for down to about 10 F. It has 600 feet of copper bured 5 feet down. I did the escavation myself it was abotu 7000$ for the equipment and about 500 for the A/C heating contractor. it is a american geothermal system direct system that means the refergent runs through the ground no water and exchange. It is good if you got the money up frount, would be fun to try to do one on the cheap with a scrap pump.

Geek

[bookman]

Would love to see some pictures, ta.

[bookman]

The thing is the heatpumps are pretty expensive things, at the moment I am subsistance living, I make very little income, just selling a little bit of excess farm produce and game meat.  What I would love to do is make GSHP from scratch, will have to visit the local scrap merchant and try to scrounge some bits and pieces. If I make any progress I will let you know.

Many thanks for all the replies.

[RatOmeter]

My brother has a 3200 sq-foot house that is heated and cooled by a ground source heat pump. The installation added about $15,000 to the cost of his new home in 1990-something (really only a 3 or 4 thousand more than a more conventional CH&A system).  The source/sink is a lot of plastic pipe which was stacked/zigzagged back and forth vertically in a trench that was about 10 feet deep and 50 feet long.  I don't know how much total length of pipe.

The exterior walls of his house are 2x6 construction (as opposed to 2x4), allowing for extra R-value in insulation. My brother claims that his heating and cooling bill is extremely low with $159 being the highest monthly bill he's ever had for his all electric house.

BTW, notice the domain for the site linked above? A great deal of research has been done here at OSU over the last decade and a half in GSHP... Dr. Jim Bose playing ringmaster.

[RatOmeter]

Almost forgot to provide a gratuitous, family-promoting picture.

My brother's house (no heat pumping shown), designed by our father:

[whatsnext]

In that case the least expensive route to build a heat pump I can think of is to modify a window AC unit. It would seem pretty easy to bury an evaporator underground. A long loop of copper buried deep in wet soil might do it. It would not be switchable to AC use in the summer but then you might not need it to be.

John.........

[whatsnext]

Bookman, Just for fun I went and looked at a 5200 btu 115VAC window air unit, it was a 10 seer device. The data tag said 5 amps. I was really surprised. 5400 btu of resistance heat is more like 13 amps at 115 VAC. This means that a 13000btu GSHP would use about the same amount of juice as a 5400 btu electric heater. Very cool, err, warm.

John........

[robotmaker]

Email me at robotmakr@aol.com and I will send you some pics.

rj

[finnsawyer]

Around here the Earth's temperature is 48 degrees F not 55.

[juiced]

"Geothermal Energy: Cheap Alternative to Natural Gas

(Allen County-WANE-October 1, 2004) With heating costs expected to be expensive again this winter, many people are looking for cheaper heating alternatives.

While it's not commonly known, one alternative has been around for 60 years. It's Geothermal Heating and Cooling, and it has been picking up in popularity.

The geothermal system uses plastic pipes submerged to the bottom of a pond to collect the Earth's natural heat. The system then transfers that head through the pipes to the connected building.

One of the largest ponds in northern Indiana used for the service could offer a 600 ton heating and cooling capacity. That could result in great savings for consumers.

Autoliv, a company providing Geothermal energy, couldn't give specific savings statistics, but did says a 2,500 square-foot home would pay $1,000 annually for natural gas, while the same home would pay $500 for geothermal energy.

The equipment used for geothermal energy is, however, more expensive than conventional heating. Equipment typical costs $1,500 to $2,000 more, making the savings come after a long-term investment.

http://www.wane.com/Global/story.asp?S=2376284&nav=0RYbRXki"

 From what i understand you need some 300 feet of tubing buried approx 7 feet is a back and forward motion under your yard/lawn. This combined with a solar heater and smart heat exchager will suffice.

  Over all cost.. maybe 4000$ CDN in parts? (not including solar heater, which can be DIY as well)

[gonedrovin]

G'day Everyone

I been looking for a discussion on ground source to try out some ideas.

I am interested in using ground source but not the heat pump.

Where I am (Australia) the earth temp at 5 metres (Measured by me) is a constant 18 - 19 C.

That's a great temperature as it is when summer outside temperatures are up to 45C, and in winter, we only need another 4 - 5 C to get up to warm & toastie. wjho needs heat pumps??

I am hoping to get a good GS system installed..probably 2.5 cm HDPE down 10 or 20 shallow bores (20 or 10 metres) and run the water through larger bore headers and some sort of heat exchangers.

If I can combine this with solar collectors a) to boost the heating in winter and b) to regenerate a desiccant wheel in summer, we should be cheering.

Sadly, in Australia GSHP systems are almost non-existent, so I'm finding it hard to get good info.

Any ideas any of you blokes might have on heat exchangers for this system, and on sourcing desiccant wheels would be appreciated.

Gonedrovin