Earth tube cooling: Why not clay/concrete pipes?

[domwild]

In the Middle East the mosques and surely some houses are cooled via porous clay or concrete pipes laid into the ground.

The air for cooling the mosque comes from the tower (minarette) the faithful are called to prayer.

Clay/concrete pipes into damp ground would cool the air adiabatically. Is this clay/concrete pipe solution too expensive compared to PVC and is therefore not listed on any of the many links when googling for earth tube cooling??

Or does the air smell badly as it wafts over moss covered insides??

[ZooT]

I don't think I'd worry about moss, but instead about other nasties that could grow in there.

I guess some folks that built "rock box" thermal storage devices had problems with nasties growing in them too....

[wdyasq]

ZooT got that one right. Many of the early rock bed thermal storage things got mold/fungus infested and were removed. In all of the projects I have planned, I planed on designing where any cooling tubes would have clean-outs and one would be able to clean the tubes if necessary. They would also need to drain any condensation to a sump where it could be dealt with.

One should remember it takes probably 20F 'Delta' before any effective cooling can take place. 40F+ Delta is what AC folks want for effective cooling and humidity control.

The ground temperature at any reasonable depth will be the average temperature for the area. Here, in North Central Texas, it is in the low 70F range at 20' or so. Seldom would it be useful for cooling. Heat is not a problem in a sunny climate.

A clay pipe system here would be a giant petri dish.

Ron

[DanG]

Here in Minnesota we get molds growing in & under snow that damages lawns regularly.

If there is stuff that thrives under snow think how much more the wee-beasties will bloom at a tropical 60°F and if re-circulating household air those are YOUR wee-beasties from microscopic skin flakes, cough and sneezes, pets, cooking and whatever was in the home before you arrived. If you decide to provide for some energy savings by using earth temperatures make the system scrubbable or floodable using non-porous plastics...

[BigBreaker]

You might be better off with a heat driven cooling strategies - kind of counterinuitive.  

One method is to use silica gel to dehumidify incoming air.  Heating the silica gel releases the trapped water and recharges it.  The incoming air can be dried so completely that a swamp cooler is effective.

There are also water chillers that use an ammonia cycle with hot water and cool water.

Another way to go is a ground source heat pump.  That will take some watts though.

[fcfcfc]

Hi: I have mine that I just put in for my new storage building, I used 12 - 100' lengths of 6" PVC flex drain pipe. The pipes all run in parallel. This summer will be the first. I plan on hanging 3" dia chlorine tablets at the air inlet and put enough tablets in to make the incoming air at about the same level that you get around a YMCA pool. The air goes in and out, no recirc.. If that doesn't work or seems un necessary, I will just flush them going into Summer and leaving Summer with a Clorox solution... Plastic is light, fairly cheap and easy to work with...

[befnme]

We have large hog houses here. And in order to efficiently cool them we use "cool cells" . What this does is pull ground water by pump into the top of cardboard type material. As this happens fans on the inside of the house pull hot air from outside thru the water and cool it considerably. As the water flows from top to bottom it goes back down into a container to be leached back into the earth.

[jtashijan]

How has your earth tube worked out?

How did you determine how long and big your tubes would be?

[bgarrett]

I got some engineers to make charts showing size and length for pipes.

I want 4 tons of cooling for a 40 X 40 with 14 foot ceilings.

12. " at 100 feet long is ideal for me but I havent found 12" elbows.
    
12. " PVC is commonly available but I need elbows.
    

[bgarrett]

that came out weird looking.  

Its 12 inch PVC in my post above

[Danthecook]

I am in Central Texas where we dream about water and am atop a hill with a 300' drop to the other side of my property.  Its quite likely I will need a water tower/wind tower on top of the property.  Anyone have any URLs I might consult for earth tube cooling.  

My hill is almost tree less and damp is NOT the problem.  I am interested in any more architectural approaches to cooling I can retrofit  the house.  I got perfect north\ south exposure and sit on the south line of the property atop a 1200' hill.  Its actually one of the highest around.  I will probably need to add a water tank, rainwater harvesting (cistern in two words)and or a well ( ouch)but I have a couple of years to finish the project. I will probably have to stay on grid as I am not around enough to physically maintain batteries.

[bgarrett]

http://www.acresusa.com/toolbox/reprints/Water%20From%20the%20Hills_Prehn%20Method.pdf

[Kwazai]

http://www.ceen.unomaha.edu/solar/documents/ISEC2004-65086.pdf

http://www.ceen.unomaha.edu/solar/solar_fi.php