# Geothermal Wells ?'s



## CIW (Oct 2, 2007)

Is anyone using geothermal collection wells to heat and cool their home, greenhouse and out buildings?
We are looking to build another home that is powered by solar and/or hydro-electric generation along with on-grid power.
I believe that geothermal will fit well.

1- What kind of pipe did you put down the wells?
2- How many years has the system been running?
3- Approx. cost of system?
4- Annual maintenance?
5- What would you do different?


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## learner-57 (Oct 29, 2016)

CIW said:


> Is anyone using geothermal collection wells to heat and cool their home, greenhouse and out buildings?...


I'm not (yet), but just to clarify terminology, are you talking about this: https://en.wikipedia.org/wiki/Ground-coupled_heat_exchanger


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## haypoint (Oct 4, 2006)

A few years ago, I did the electrical wiring in a new house on the shore of the St. Marys River (it connects Lake Superior to Lake Huron). A local HVAC company installed a geothermal system that used river water to pull heat from. Worked for a few months, but by January, the water was too cold to work. The system pulled a few degrees from the frigid water and the system froze up.
They drilled two 6 inch wells, one to pull water from and one to discharge into.
The house is a log home of average size in a cold region and I think they said they had $20,000 into it.


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## CIW (Oct 2, 2007)

With what I'm coming up with, the initial investment is about 20 to 25,000 for a high average sized home. (2200 sq. ft.) The good thing is that the federal government is reimbursing 30%. Some states also kick in. 
The greatest thing is the monthly costs to operate the system are really low. And you end up also getting about 80% of your hot water provided through the system if you set it up that way. Most people that I've spoke with and heard of, have a total household electric bill of $100 monthly. That's an all electric home. That's all your utilities. You pay to run a pump, fan and a compressor. And the pump, fan and compressor can be installed to use 24v if wanted. You don't have to convert voltages if you are using alternative power sources such as personal hydro-electric or solar. 
Learner,
What you are speaking about is using an shallow buried pipe to run air through, and extracting the temperature from that air. Those are done by burying pipe about 12 ft. down. Then forcing air through it.
This system is built by drilling deep wells and looping pipe down in them to run water or glycol through. It's a closed loop system. Down that deep the temperatures are much more constant, and somewhat higher (around 66 degrees F) when you get below 150 ft. The other thing is that you are able to heat and cool home home with this system using the existing ducting to condition the air. It also is being adapted to in floor heating. Another thing is by drilling wells you don't need a lot of ground like you would using the warm air system. They are being used in many city homes with small building lots.
Please don't think that I'm down playing the air system. It has it's place. And works well in greenhouses and such. This closed loop liquid system seems to be more consistent for home use and more adaptable to current construction practices. 
This is what I've come up with so far. And I'm still searching.


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## markt1 (Dec 15, 2013)

I have geothermal heating of my house. A pump-n-dump system. Was initially installed when house was built in 1985. We bought the house in 1998 and the thing died on us in 2006. Cheapest replacement unit with a copper water-air heat exchanger with a four year warranty was $4200 with labor. It lasted exactly 4 years and three months. Learned my lesson from that! Went with a new unit with a copper-nickel heat exchanger that had a ten year warranty ($6300). Still running OK. Love the thing. Keeps the house 73 degrees inside year round without ever having to touch the automatic thermostat. In cold Pennsylvania winters it uses around $120/month of electricity. That's $4 a day in February in a 1200 square foot house with a full basement! My pump-n-dump system uses a source well with the water 90 feet down and a 35 feet deep drain well located 100 feet away. The water comes out of the ground at around 52 degrees F year round ( a meter displays the input water temperature). It requires a 4 gallons per minute flow just for the system, so you'd need a source well that outputs at least 8 gallons per minute so the rest of the house would have a normal water flow. The water flow reaches a junction in my basement that splits it. 1/3 for my system and 2/3 for the house. For those with a weak well, a horizontal closed loop system will work but is more expensive to install and probably a bit less efficient since the outside ground loop flow isn't really all that deep (12feet?). The electrically operated water flow valves tend to leak (I've had four replaced), and although they aren't expensive, they aren't covered by the heat pump's warranty. The repair guys charge $120 an hour to replace them! Most systems have electric hot wire emergency backup (similar to baseboard heaters) in case of winter failure. I recommend them.


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## Bob M. (Nov 5, 2018)

this is a interesting concept. I do not think this guy uses liquid but rather air, which goes through 7 lines that go out 90ft from the greenhouse location, through a average 52 degree ground. the thing with geothermal if I am right it gets warmer the lower you go, so I imagine you can sort of choose the temps you are going to get from it. air seems more stable and less costly than liquid, though and maybe less things to go wrong. I mean you do not have to worry much about springing a leak or fittings leaking. but I'm just guessing. see no reason you could not heat pretty much anything with these methods.


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## Bob M. (Nov 5, 2018)

I wonder why they didn't run it straight down. seems like it would be easier to drill a 90 ft twin hole for a u shaped pipe than a horizontal trench? also seems the earth would be warmer the lower you went down. in fact, with the properties of air density I'd almost wonder if you'd then even need a fan, as heavy colder air one would think would go down the holes, displacing the warmer air which would rise, and thus make its own cycle right? forced air would probably have higher displacement/airflow (And by probably I mean duh of course it would) but seems like one could compensate with more holes. It is intriguing to think perhaps this could be done without any electricity at all. maybe even have seebeck generators to create electric for themselves.

Then again you could always grow a bunch of potatoes and stick electrodes in them...or use those lemons...ar ar....


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## Bearfootfarm (Jul 13, 2006)

Bob M. said:


> It is intriguing to think perhaps this *could be done without any electricity at all*. maybe even have seebeck generators to create electric for themselves.


That's not how the real world works.


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## Meinecke (Jun 30, 2017)

Geothermal would be nice...but these differential vacuum systems are high maintenance and high electricity Gadgets...
But for GeoThermal you either need to go way deep or sit/live on a thin crust aka YellowStone or Scandinavia
So besides photovoltaik/photothermal collection, you are pretty limit with "harvesting" the elements...
If there would be a viable solution out there, they would either hide it to make more money on garbage or everyone would sit on it already...
Best bet is, what i saw on a House expo...
House build around a 1300 gallon water tank that goes from Basement to upper floor ceiling...super insulated and fed from solar panels and photothermal panels...
House heated from that storage tank with floor radiant heat inl shower and regular tab water...
Was advertised to withstand 3 weeks without sun...additional wood stove in living room was holding curls to heat water in case you needed to add heat from "artificial source"


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## markt1 (Dec 15, 2013)

Meinecke said:


> But for GeoThermal you either need to go way deep or sit/live on a thin crust aka YellowStone or Scandinavia


This is absolutely NOT the case. You don't need deeply generated steam temperatures to make geothermal work. My geothermal system ducts only kicks out 85 degree air flows and works perfectly fine. Once you go down around 10 feet deep the ground maintains 52-54 degrees year round. In fact, if you were to run water from a 10 foot deep well through an inside big truck radiator with a fan over it, you could keep a well insulated house at 50 degrees in winter. If you ran that water first through a pipe centered in a large reflective parabolic fixed trough with a low concentration ratio, then into a large inside water tank, then through the truck radiator, you could have 70 degrees inside in winter around the clock. This system would use solar to warm the well water up to 80 degrees and be extremely efficient. The well water's ground temperature would be supplying 2/3 of the needed energy, with solar supplying the remaining 1/3 of the energy. Only the well pump and duct fan would need electricity. If my current geothermal heat pump dies on me, I just might try this out for my house.


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## shawnlee (Apr 13, 2010)

Best to clarify as there are many geothermal versions out there...some great, others are cash cows.


Basically the cheapest/easiest are the heat pump ones...…..where you have a standard A/C style heat pump with a Freon to ground water exchanger.

It cools the Freon in the summer and heats the Freon in the winter...……


Same with the current hybrid water heaters...…..they are heat pump style and run one way so the hot coil is always in the water.

Heat always moves towards cold in BTU law...….

Basically standard HE geothermal systems use a exchanger on the condenser...….to transfer heat in the summer to the geo water and when in heat pump mode it runs the system backwards so it transfers heat from the water into the system or coil, which has now become the condenser when it runs the system back wards...…..if you were to install a window A/C unit back wards in the window it is a heat pump.


The cooler you can keep the condenser, the outside unit in the summer, the more efficiency the system has, so it sits outside with a fan removing the heat from the Freon thru a fan on the outside condenser, instead of a fan and outside air, geo uses the 50 something degree water to remove the heat.


The system works backwards in the winter, turning the inside coil into the condenser which gets hot and now the outside coil gathers heat, problem is when it gets below 32 degrees it uses crazy power and does not work very efficiently, so we use a water exchanger/geo which is 50 something to pull the heat from the geo water which is very efficient.

Think of a window unit AC......cold inside is the coil, hot outside is the condenser......to make it a heat pump all it does is run back wards, now the outside one is cold and inside is hot.


2 pieces....the coil gets cold, condenser gets hot...…..when in AC mode the heat inside is sucked over the cold coil, the more cold removed the hotter the outside condenser gets because it is working harder to remove the heat from inside the house...……..….when in winter heat pump mode, the system runs backwards...…..but still the same principals apply. 


The inside coil now becomes the condenser and the cold inside air is drawn over the condenser heating the inside...…..problem now is the same as summer......cooling a super hot condenser outside in the summer sun or warming up the outside coil which is freezing cold in the winter.


By coupling the condenser/coil or the exterior one or simply one of the exchangers...it does not have to be outside anymore....with the 50 ish degree ground water...…...now the hot coil is easily cooled in the summer and the system easily draws heat out of the water in the winter boosting the efficiency of the system in both winter and summer and overall lowering the bill all year long.


There are many other styles, but that is by far the cheapest and biggest bang per buck, you circulate a sealed length of coolant thru the ground so it is a sealed system that never freezes and reduces scaling compared to a pump and dump where cool well water is ran thru the exchanger and then dumped out....those systems can freeze and have scaling problems in even the best conditions.


Ideally a sealed exchanger side with distilled water and antifreeze/alcohol is used and pumped thru X footage of line buried 6 feet or soo deep or in vertical wells/runs ideally that go into the ground water so the distance of line to pick up and release BTU`s is not as long.


This system can be made to be insanely expensive or a super cheap DIY project, just depends on what you want and who you ask.

The only thing different about one of these systems is the pipe in the ground outside that circulates like a radiator and the water to refrigerant exchanger...……


It still has all the same things as a normal system...…..pipe or wells outside is a huge cost but can be mitigated, the interior unit/exchangers is where they charge a premium , but that too can also be mitigated.


A Freon to water exchanger is not that much money...…..since that is all that changes, well a circ pump to keep the water moving when the system is on, but that is pretty simple to do.


Ground tied geothermal heat pump is what it is.


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## CKelly78z (Jul 16, 2017)

I like the underground air tube system that was used in the video in Bob's post #6. My plans are to build a hoop house/high tunnel, that would be far more usable if I could have a heat source for the Winter, and a cooling element for the Summer. I have the property, the backhoe, and not afraid of some hard work, and construction. If it works well, I may use a system in my house.


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## JeepHammer (May 12, 2015)

While both geothermal, you are comparing apples to oranges.
This is like comparing AC systems to DC systems, or solar electrical (PV) vs. solar thermal (hot air or water).

Unless you use radiant mass (like radiant floor heating in a concrete floor) the LIQUID filled tubes used in deep well aren't practical.
When using a 'Heat Pump' and deep wells with liquid filled lines, there is a liquid to air conversion that needs to happen (heat exchanger).

With geothermal AIR (open, large air tubes) you use the air directly, no heat exchanger needed.
The air comes in from the tubes at ground temp (around 65*F around here) and I only have to heat that FRESH air 5*F-10*F to make it very comfortable.
By recycling the air in the house, even less heating required.

The same is true in summer, although we recycle a lot of home air in the summer because of humidity.
I run a dehumidifier, and I don't care to use as much fresh air in the summer since it's wet and I have to dry it to be comfortable.

No deep well drilling costs, no specialized liquid tubing, no deep well pumps running...
Just large loops of plastic drainage tile, a fan to draw from underground, and a dehumidifier instead of a 3-1/2 Ton Air Conditioner running day & night.

I have nothing against geothermal wells and heat pumps, it does reduce consumption, but initial cost is high and it's not simple enough to do yourself with a rented backhoe or trencher...
If you live where bedrock is at the surface, trenching isn't an option without explosives!
(Explosives are fun, but expensive)

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I built my off grid solar system, and dry/cold storage with root cellar before I built the house, so I've done this once on small scale, and later on larger scale.

The first thing going in was root cellar, cool & humid.
A good root cellar will be 85%-90% relative humidity, so natural floor, cold perforated drainage tubes to let moisture in, a floor drain to keep water from standing, and let convection do the work without added power.
As the ceiling vent draws air out of the root cellar, it's replaced from below with damp, ground temp air from the drainage pipe at 'Base Board' level.

When I had a water well drilled, I cut a hole in the floor of a shipping container, set it about 3' deep in the ground, and ran solid plastic pipe up through the floor.
I used river rock bed under the container for drainage, and eventually earth covered the container.

Again, batteries, electrical equipment needed to be vented, and fresh air drawn in, and the vent pipe above does that job with no power, although I do have an exhaust fan in the vent pipe to clean out battery gasses & ozone from the electrical equipment.

This was a NO FREEZE, fire proof place for batteries, well pumps, water pressure tanks, basically my own 'Utilities' building that can't flood since the drain is HUGE & gravity, and gravity always works...
So does siphon from the vent pipe, and convection from temp differentials.

When the cool/dry storage went in, solid pipe and vents, and again, convection with a fan if the temp gets too high.

When the house went in, and having actually stayed weekends & holidays in the cool storage while working the homestead,
I used air tubes, but much higher volume, and mixed recirculating & fresh air tubes in the air handler.

16+ years in the house, 20+ years on the homestead and I've not regretted it once.
Fresh air tubes are MUCH longer than recirculating tubes simply because it takes longer for -10*F air to reach ground temp than recirculation air does.

My tubes are 8' deep, mostly because that's all the farther the backhoe I borrowed would reach down... The tubing came from the farm store and I got discounts when I bought rolls instead of 'Sticks' (short, straight pieces).

The ceiling fans & dehumidifier consume about 1/6 the power a high efficiency AC unit do.
This makes it very comfortable for my off grid solar to keep up with...
We spent about $200 extra on propane to heat over the LONG winter, we do cook more at home in the winter which adds humidity to dry air and adds heat to the home, so $200 is an estimate for both added cooking & supplement heat.


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