Earth Tubes: How to build a low cost system to passively heat and cool your home

[forgeblast]

You may want to check out Solar Sunspaces and Greenhouses if you go down the page you will find
Subterranean Heating and Cooling System Explained which may also be helpful.

 

[Dr Dave]

This sounds like an interesting project, I think it would be better with smooth wall pipe, so water would not set in the ridges of the flex pipe. If your hill is steep enough, this may not be a problem.

You could get a peice of the flex pipe, and set up a model, and experiment on how much of a slope is needed for complete drainage.

Dave

 

[SPIKER]

This sounds like an interesting project, I think it would be better with smooth wall pipe, so water would not set in the ridges of the flex pipe. If your hill is steep enough, this may not be a problem.

You could get a peice of the flex pipe, and set up a model, and experiment on how much of a slope is needed for complete drainage.

Dave

I was thinking the same thing, some schedule 10 PVC bell ended stuff like what is used for rain drainage.

sounds like it would be better than the corrugated for humidity removal. Would be more expensive but some aluminum would really transfer temps much better but would cost 4x for materials...

Mark

 

[Artisan]

I have pondered systems like this from time to time. I believe I would pay the extra buck
and go w/ a smooth inner wall pipe so as not to have any nooks and crannies for mold
and bugs and yuck to accumulate. I would definitely install it on a grade so any water
would roll out. Smooth wall will clean nicely w/ a plumbers water jet machine in the event
it gets moldy or whatnot. If you make it so you have access at BOTH ends you can really get
after it if cleaning is necessary. Of corse if it can daylight in the basement GOOD and at the other
end maybe consider a buried tank w/ a manhole riser access so you can pop the top,
jump in and service it from the lower end if necessary.

I have thought of pushing and pulling air thru the system by using something similar to
these babies. Certainly if you can get air to exchange on it's own by thermals that would be optimal
but remember hot air rises... Low voltage tube fan(s) will be needed I do believe.


I think I would be dead set against anything other than a closed, watertight sealed system. It just seems
like your asking for problems by slitting tubes and all that. Just throw down some ABS or PVC and
solvent weld (glue) it up water tight. Yes spendy the pipe is but consider sealing that system up
and the money lost if it becomes a liability for whatever reason due to it being "slited" etc.

DO it nice and straight if you can so a flashlight will work somewhat
when you need to look down it.

Take pics and post up as you go!

 

[EMB5530]

The only problem w/ the pvc pipe is if he is having it ripped in like most drainage tile its gonna cost a LOT more to install than the original estimate.

 

[chim]

As long as there's condensation. even the smooth pipe could be a breeding ground for mold. Not necessarily a game stopper, but a concern.

The one thing I didn't see mentioned was that corrugated pipe has a lot more surface area for heat exchange. If you could take a tape measure and follow the wall of the corrugated pipe, you may find it takes twice as many lineal feet of smooth pipe to be the same effective length.

 

[stingray1]

The one thing I didn't see mentioned was that corrugated pipe has a lot more surface area for heat exchange. If you could take a tape measure and follow the wall of the corrugated pipe, you may find it takes twice as many lineal feet of smooth pipe to be the same effective length.

I agree

 

[jenkinsph]

I think the idea of sloping the pipe to drain the condensate is a good idea but would use smooth pvc pipe instead of the flexible pipe that will hold the water.

I also would suggest you use a lot more tubes to get better results, just using 3 or 4 tubes isn't going to help much.

CNC Dan suggestion to use a ground source heat pump works on the same principle but eliminates the cross contamination of the air systems. Might be a good add on for your new mechanical system considerations.

 

[jenkinsph]

The one thing I didn't see mentioned was that corrugated pipe has a lot more surface area for heat exchange. If you could take a tape measure and follow the wall of the corrugated pipe, you may find it takes twice as many lineal feet of smooth pipe to be the same effective length.

While the surface area is increased with the corrugated pipe it won't make any difference long term as the soil temperature will average these differences out rather quickly. Conduction of the heat through the soil would be the bigger issue. Both pipes smooth or corrugated will develop a skin of dirt or soil around them which will be close in temperature to the inside pipe wall in a continuous run situation.

 

[fordmantpw]

I think you would be better off using a ground source heat pump.

Ding ding ding!

When you figure the costs of your system (not just install costs, but ongoing maintenance, ensuring no mold, etc. issues) plus the cost of a standard HVAC system, I think you would be money ahead to put in a geothermal system. With a 30% tax credit, it's really not that expensive, and they are extremely energy efficient. You get the benefits of the earth without the drawbacks of earth tubes.