General discussion

Tapping the Earth for home heating and cooling

Two points:

Below the frost line in your area the temperature remains a constant 55 degrees fahrenheit.

Heat pumps do not work at temperatures below 32 degrees fahrenheit. During these times heat pumps often are switched off and electric heating begins.

These system are very efficient because they can use a heat pump the year round regardless of low temperatures.

Myself I believe geothermal should be used to create a protective envelope around conventional houses of 55 degree temperatures. Simply heating and or cooling attics and crawl spaces with 55 degree temperatures would have a profound impact on a homes heating and cooling. This can be done without elaborate heat exchange systems using an earthen trench, some 6" plastic pipe and a small blower fan, like those found in many bath rooms. Trench 400.00-700.00 dollars (US), plastic pipe 200.00-300.00, fan 30.00+electrician 100.00= 130.00. Total cost 730.00-1,130.00. Half the cost of a furnace replacement in the conventional average home.

It's possible problems:

Black mold could contaminate the system

High humidity created by the system could lead to dry rot.

Sizing the system to fit ones house. This might require some engineering costs.

All of these problems can be over come.
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Think about this more...using the underground

So we get nearly free air conditioning in the summer and supplementary heating in the winter? Of course we would be causing temperature changes and fluctuations below this frost line. What physical changes happen to objects or substances with heating and cooling? How about expansion and contraction? And what about vegetation that plants roots deep down into these areas we'd be monkeying around in? Will they tolerate theses changes? I also would have to think it take a more efficient heat exchanging system than just plastic pipe....which is actually more of an insulator. It would take metals or maybe some ceramics. This will surely drive up the cost and I don't think a 30 dollar bathroom fan that might help remove offensive odors in a bathroom is going to do much to bring heat into a house from a subterranean plumbing network.

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actually it's been very well thought out

Like the volume of stored heat below the frost line. Think about the volume of stores heat available all the way to the Earths core for instance.

Plastic though not terrible efficient would do just fine if long enough. In fact many solar hot water systems use plastic pipes/tubes as heat exchanges.

No matter what the size of the fan it would be far less energy intensive then a heat pump or gas or electric furnace. This system used to supplement these systems would increase there efficiency considerably. My guess is in some areas of the Nation illuminating cooling all together. In other areas reducing energy costs dramatically. Unlike other forms of alternative energy geothermal can be used nearly everywhere. It is a nearly universal source of 55 degree heat world wide.

I'm not the one that needs to think this through more thoroughly. In fact this is nearly a "no brainier".

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That 55 degree underground temperature

Do you think that temperature is going to remain at a constant 55 degrees when someone pumps hot air or water down into it in the summer and cold in the winter? The heating and cooling efficiency will decrease throughout each season. There's a reason that temperature remains relatively constant. It's being left alone to natural sources of heating and cooling that act upon it very slowly. These systems might have benefits on a small scale where the relative impact isn't that great. Think about building a house out in the middle of no where and drilling a well for your water supply. You may not need to go very deep. But, you start getting neighbors and they drill wells too. Guess what happens to your shallow well water supply?

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Any HVAC/thermal engineers out there?

How much trench area at 3' in depth would a 4,000 square foot home need, perhaps a square foot value would be best. I realize this is more complicated then it appears. Can you give us an average based on a typical/average home, some "ball park" rough guide line?

Simply created a looped system would greatly reduce the length and possible problems with this system.

An additional problem would be the insulation methods used to reduce heat loss in most homes. The rafters in a house would be best insulted not the ceiling. Exterior foundations walls would also need to be insulted for crawl space areas. In some instances preexisting insulation could simply be relocated. Example: move insulation from ceiling joists to rafters.

A concept can not be patented. This is a freebie for those that might wish to experiment. Do so at your own risk. This concept is experimental.

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Done, done, and done.

My folks had geothermal heating in a home over 20 years ago. Noisy, leaky, and trouble during power outages, especially during the freezing winter months with all those pipes to crack. Supplemental electrical heat was still necessary at times. Also it takes a LOT of fan to blow that much air (hot or cold) around a house. It also could not supply hot water for showers, dishwasher, or laundry efficiently as it required electric supplementation to heat water to the proper temp for nearly all of those uses.

They said they would not have wasted the time or money and would have gone a different route had they known.

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Go for it...

Make millions. Or not.

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Septic tank heat storage

All your hot water from showers go down there already, if you have a septic system. One could use solar passive heating with heat exchangers to store excess heat in the septic tank water where it can later be extracted for home heating purposes. Better might be using it in a gray water system. You both gain the heat input into the ground and the earth radiant heat, plus the thermal mass of the earth surrounding the tank. What water goes down the drainfield just puts the heat along that line and some heat exchanger lines can run in the ground a foot above the drainfield line too. Used in a heat exchanger system, shouldn't be problematic. Input heat from solar in the day for enough stored to allow extraction during the nights.

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Two thoughts ...............

This would have to be water/antifreeze system because of methane gas created by those bacteria.

Skip the sewer and install a separate septic tank without the bacteria. This would work just as well without the complications.

The beauty of the geothermal concept I've mentioned is it's simplicity and low cost. It could be retrofitted to nearly any home and would be nearly invisible. No fancy pipes, pumps and complexities to deal with. It would not require a newly constructed home to make it work. In fact it could be constructed by nearly anyone with the most basic construction/handyman skills in a few days. An Engineer would need to be consulted to determine it's length and an electrician would be needed to do the wiring.

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I have cousins that did this

They built a house with the ducts going under the house so the air going into the furnace or air conditioner was 55 degrees using less utilities.


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Something doesn't sound right with this idea

as far as energy savings but I do remember the downside to the caulking and weatherstripping rage of years ago. A gas furnace tends to deplete the oxygen we need to breathe and it's necessary to replenish that with air from the outside. One method was to duct in outside air for the furnace's burner intake but, that air being colder, would cost a bit in energy usage. I could see that pre-heated air from the outside would help a little to keep the loss down. As for AC, the outside air would need to be fed to the air intake side of the blower. It would be bringing in the outside humidity which is something your AC is trying to get rid of. For air to come in from outside, some of the cooled air would need to be forced to the outdoors. Something's not making good sense here as far as energy savings. Confused It would, however, keep the indoor air oxygen supply up.

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I don't know

I saw the house as a twenty something but didn't crawl around underneath. They're the ones that thought my eight-year younger sister was thought to be older than me. Wink


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Many home and most new homes

come with drainage systems that surround them. This might be adapted to work a little better then the homes sewage system. Happy I'll let "you" try that sewer idea Grin

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(NT) Looks like another good thread to follow for info.
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can you add some?

Ideas help.

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Nope. Just be careful with all that water flowing

around your house.
The posts seem to be covering the main parts and some of the details. There's also the thread on taboma's Magnificent Machine, which is also interesting, if expensive. I'm watching that one, too.

Much of the solar stuff can be homemade. Example: Get discarded water heaters for storage. Many of them have only dead burners and such; they still are insulated tanks. Put 'em on the south side of the house, getting water from hoses on the roof or other collectors. Like the comment about '55 degrees is a better starting temp than freezing', roof water is even better as a pre-heated input to one's normal heater.
I also remember having it pointed out to me that tank and pipe insulation is useful even in summertime- unless ambient in your area is always 120. Happy

IOW "solar heat" can mean merely water running through a black-coated surface.

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I do think it's interesting that the concept

is similar to that of living in a cave which would take advantage of the large volume of earth and rock that acts to regulate temperature within. So does all this means that man's desire is have a cave like atmosphere but with windows? Happy

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latent heat value

water has a large latent heat value, can store up a lot, and that found in septic systems won't be susceptible to freezing below ground and with it's normal salts included. Using a heat exchange system utilizing antifreeze solution between the storage and the sunlight collectors converting it to heat will keep it sanitary. All heat used for home can be extracted with heat pump coils directly placed in the septic system, minus fins, so probably coiled copper tubing, might need some added coating on the tubes. Cutoff switch if the septic system water drops below 40 degrees to avoid freezing problem in the septic drainage part. In such system, larger septic tanks would be called for and the system could be done in a way so the heat sinks and heat exchangers would help baffle the flow increasing the efficiency of the septic system too.

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Of course...

Of course, you would want to make sure that the liquid in the septic tank didn't get hot enough to kill off the bacteria which are necessary for normal breakdown.

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bigger problem would be winter

That's the typical time when septic systems have problems, possibly due to lower tank temps, and using it to extract more heat would lower those temps even more. Settling would still go on, but bacterial action might cease till the cycle reversed. It was a thought, but without solar heating adding to the septic heat, probably not feasible for winter heating purposes.

On the hot side, I don't know the temps at which the normal bacteria would be killed off, but if the septic temp exceeded the ambient air temp, then a switching valve could be installed to switch the heat pump to an air cooled condensor instead.

The whole theory of using a ground system with heat pump is storage of heat in summer for winter use and cooling the ground temp in winter for summer use.

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Yeah, as I noted earlier, there are details to be

worked out in any system.
And don't forget to follow local codes where applicable, otherwise you end up with a well-conditioned house that you can't sell.

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Question about septic systems

Don't these work by bacterial breakdown of solids and doesn't this generate some heat? Isn't that heat needed to make the process efficient? If we interfere with the normal temperature regulation that occurs down there, won't that be detrimental to the needed biological processes?

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but a double tank system in which the heat is extracted solely from the effluent might work fine.

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RE: doesn't this generate some heat?

not enough to melt the snow that is on top of a septic tank that is only buried 12".

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(NT) ... windows and a wide screen TV.
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those monolithic domes

I've often thought about living in one of those with NO windows, instead have a few LCD screens around switching scenes from outside cameras so they acted like a "window". You can pick up a lot of earth heat just by having a basement in a home too. An air exchanger will allow fresh air while helping to regulate temperature. The type I'd want is a bit different than what they usually build. I'd want both outer and inner concrete shell with about 2 foot of expanded foam between them. Would serve as a home, weather proof, small bomb proof, and without a direct hit even nuclear bomb proof.

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I like the black box out the window idea

use styrofoam to insulate a box with black primer painted tinfoil and covered with clear plastic. Dryer hose hangs down to floor on inside and heat exits from window, closed onto the box. Sun hits black metal, absorbs and converts to heat, flow is passive. At night, pull the box back in .

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Ideas and reality

Its not just below the frost line its rather deeper than that. But yeah, its starts to get 55deg. at that point. From what I've heard its drilled(down)in multiple tubes/pipes that are needed for the amount of the sq.ft. of a house, yada, yada. Our city did this for a single level building and far bigger than a home but the cost was in the $1.5M range. of course the payback with return compared to cost of fuel and the yrs. of trouble free usage. More contractors are offering this service, but it really has to be done right and as always the cost tends to be more expensive. As for costs you provided this seems way too cheap, IMHO for true geothermal install. It seems far too simple, though contractors offer it now but comprises of a lot of more footage of piping.

Alas, I know of frost line issues as typical in our area 3ft. is required for pilings and/or concrete posts/foundations, etc. in order not to be affected. Recently, i replaced my well piping and pump in order to be updated and less troublesome. BUT!!!! i live above solid limestone and the dirt covering it can be anywhere from 0-30in. deep around the house. My plumber(neighbor) and I replaced(5/15/0Cool the piping along the top surface of the limestone as that was the best we could do and was as it was under the old system. I did insulated the piping going up by hand(sill insulation) and thru the foundation. Currently, its at -5deg. today(1/15/09) and no frozen well pipes, phewwwwww! adios from the cold Midwest Ohio. -----Willy Happy

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rent a ditch witch
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it's called the frost line because from this point lower the ground does not freeze. Freezing, of course, happens at 32 degrees fahrenheit. A layer of say perlite/insulation can fix that very quickly at a low cost. Styrofoam beads would do the trick also making back filling that trench easier. Happy You could also go "very deep" with the trench digging and reduce or eliminate any costs for insulation.


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tapping the earth

i think that we have to get the free air conditioning...haa...its understood man that we will b e a cause of the temperature changes.but the question is that what the physical conditions happens?????

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