[puttster]

Back before the internet I built a pier and beam cabin with a 10 x 10 basement. I had the backhoe man trench out fifty feet from it and in the trench I laid 55 gallon steel drums (ends cut out) for ventilation and escape. The barrels were not connected and on top of them I simply laid screen, then backfilled.

The ventilation "system" was a 3'x6'x 6"deep 45-degree south-facing rooftop solar box that was supposed to exhaust its heat out of the top and pull cool air from the tunnel, hopefully beating the steaming Texas Summers.

Unfortunately I had to sell the property before I could test it out but I wonder if it would have worked as planned. Especially wondering because I am thinking of doing something like that again but hopefully this time with the wisdom of some knowledgeable folks.

Thoughts?

putts

 

[Watch Ryder]

Hmm, got any pics you can scan and whiz on the net?

 

[IamZeke]

I've seen some of this done on the internet and I believe their are a couple pro outfits doing this. They call it earth-tubing, though wiki likes to lump it in with other similar options. Some folks do this up big time. Your plan should have worked if laid out right, though how well would have been a function of volume, depth, and distance on that vent tunnel. The folks getting good results use some real big and very long lines. If yours had worked enough to drop the temp 5-10 degrees that might have been handy in a Texas spring or fall, but summer time would still likely have been a scorcher unless you had additional cooling options.

I did a bit of googling for you.

http://en.wikipedia.org/wiki/Ground-coupled_heat_exchanger

http://www.earthairtubes.com/

http://www.daviddarling.info/encyclopedia/E/AE_earth_cooling_tube.html

http://mb-soft.com/solar/saving.html

Interesting passive idea, though I wonder how well it will work in high humidity environments.

 

[Dragonid]

My first thought is that the cut barrels aren't very structurally sound. Culverts from either corrugated metal or concrete would be much more capable, and could be of a more convenient diameter.

For heating/cooling it could work well if the rate of flow could be controlled to ensure that the air drafting through the tunnel had sufficient time to change to the desired temp. In areas with a high water table, it would quickly become dank and musty though, and not be very useful for that purpose.

 

[puttster]

Good links, now I know I was building an Earth Tube and a Solar Chimney (though I actually used a roof turbine for exhaust).

Yes the tunnel was pretty dank but I never got it connected so air would flow through it. I now think the tube air would have been 86 degrees. Better than 100 degrees I guess, but not sure it would be worth all the work just for that.

I would probably stay with used barrels - $10 each, 100 feet for $350. A hundred feet of 24" corrugated pipe would cost $2,000. Anyone try crawling through 24" pipe, please give us your experience!

Tunnel did not collapse. Maybe by now it has, though, from being rusted out. I wonder if plastic drums would hold up. Plastic would be easier to cut the ends out of but you'd need to be more careful back filling...

I never found out if I would have needed an electric fan to get the heat flowing through the system. Reading those links sort of convinced me that I would need a fan, otherwise, even with the collector at a 45 degree angle, the air itself might not get a move on. Anyone have some calculations on that, like cfm per square foot of glass, etc?

I also saw some interesting additional applications for the solar panel that I didn't know about back when I build it. With a little extra duct work it could be used as a dehydrator and a window box heater (for winter).

Sorry, no pics except of a 3" thick water moccasin that had gotten in the basement, probably through the "escape" tunnel!

 

[IamZeke]

Good links, now I know I was building an Earth Tube and a Solar Chimney (though I actually used a roof turbine for exhaust).

Yes the tunnel was pretty dank but I never got it connected so air would flow through it. I now think the tube air would have been 86 degrees. Better than 100 degrees I guess, but not sure it would be worth all the work just for that.

I would probably stay with used barrels - $10 each, 100 feet for $350. A hundred feet of 24" corrugated pipe would cost $2,000. Anyone try crawling through 24" pipe, please give us your experience!

Tunnel did not collapse. Maybe by now it has, though, from being rusted out. I wonder if plastic drums would hold up. Plastic would be easier to cut the ends out of but you'd need to be more careful back filling...

I never found out if I would have needed an electric fan to get the heat flowing through the system. Reading those links sort of convinced me that I would need a fan, otherwise, even with the collector at a 45 degree angle, the air itself might not get a move on. Anyone have some calculations on that, like cfm per square foot of glass, etc?

I also saw some interesting additional applications for the solar panel that I didn't know about back when I build it. With a little extra duct work it could be used as a dehydrator and a window box heater (for winter).

Sorry, no pics except of a 3" thick water moccasin that had gotten in the basement, probably through the "escape" tunnel!

I don't think yours would have done a lot of cooling in a Texas summer. Spring or fall maybe, but you would have needed to rip up a half acre and go pretty deep to offset a Texas summer. See some of those jobs done in the 2nd link and remember they are more north of Texas. Still, every day the A/C is off is money in your pocket, so it's really a matter of your fixed costs to do it versus the return savings on days without running your A/C.

You could have used a solar panel to help power a fan on sunny days to help move the air, btw.

The last link is a mess but contains most of the calcs you need.

 

[TheFittest]

What if you dug a trench just big enough to fit the drums with a few inches around them. Placed the drums in the trench on top of spacers that will keep them off the bottom a few inches, and use duct tape to hold them together. Then slowly pour in concrete over and around the drums. The concrete will add an insulating thermal mass around the drums as well as keep structural integrity long after the barrels would have collapsed on their own.

Seems like a cool idea, and would a nice way to cool a house in the summer. You may even be able to use a thermosiphon if you can seal/insulate your house VERY well. Use an attic vent/fan to push out the rising heat. and draw fresh air in through the underground tunnel.

If you live in a humid region, you will want to put a slant on the tunnel, and have a sump at the bottom end. The cool ground around the tunnel will condense the water in the air, and naturally that water will need to go somewhere.

You will need the tunnel to be deep enough in the ground to have a measurable impact. In most regions you will likely want it 36-40" down...

I'm not sure how much cheaper this would be then a standard geothermal heating/cooling system, but one thing I do know, in the instance of an emergency, you can't squeeze down 2" flexible pvc...

 

[Einzelganger]

For the purpose of escape, you should also consider sound as being an issue because I know a guy who did a project like this but because he didn't go deep enough, you could still hear the sound of him moving around in the tunnel from above ground. And all I had to do was follow the noise that he was making to the exit.

 

[bilmac]

I doubt they will last very long before rusting out. I'm surprised at the cost difference between barrels and culvert

 

[IamZeke]

What if you dug a trench just big enough to fit the drums with a few inches around them. Placed the drums in the trench on top of spacers that will keep them off the bottom a few inches, and use duct tape to hold them together. Then slowly pour in concrete over and around the drums. The concrete will add an insulating thermal mass around the drums as well as keep structural integrity long after the barrels would have collapsed on their own.

Seems like a cool idea, and would a nice way to cool a house in the summer. You may even be able to use a thermosiphon if you can seal/insulate your house VERY well. Use an attic vent/fan to push out the rising heat. and draw fresh air in through the underground tunnel.

If you live in a humid region, you will want to put a slant on the tunnel, and have a sump at the bottom end. The cool ground around the tunnel will condense the water in the air, and naturally that water will need to go somewhere.

You will need the tunnel to be deep enough in the ground to have a measurable impact. In most regions you will likely want it 36-40" down...

I'm not sure how much cheaper this would be then a standard geothermal heating/cooling system, but one thing I do know, in the instance of an emergency, you can't squeeze down 2" flexible pvc...

Flex piping is likely less expensive and won't corrode.. You also want to get reasonably deep too.

 

[escape]

Neat idea, however I'd feel much more confident in the long run with either galvanized culvert.

 

[LordOpie]

does the new owner of the property know about the tubes? I'd hate for someone to get trapped in them cuz the new owner didn't close it off.

 

[TheFittest]

If you covered the barrels with concrete wouldn't that solve the structural integrity issue? Even after the barrels rusted the concrete would remain solid and strong...

 

[puttster]

If you covered the barrels with concrete wouldn't that solve the structural integrity issue? Even after the barrels rusted the concrete would remain solid and strong...

Probably would be easier and cheaper to just buy concrete culvert.

 

[Sooner_Will_Survive]

more and more are going geothermal. what they do is drill holes 50 to 100 foot. then they put loops that run water through it into a heat exchanger. this is a preheater/cooler for the central air. the idea is instead of cooliing 100* temp they are cooling 80* temp air which uses less energy. and on the flip side when heating instead of heating 50* air they are heating 60* air resulting in less energy used to heat. those #'s i have made up but i believe the temp is a cool 68* in most caves. and they is what they are trying to duplicate. so you can hire a geothermal contractor and eng. have them drill the holes and add the preheat/cooling system to the central heat and air.

 

[Writer's Block]

using barrels does not sound safe to me.

 

[Dragonid]

...those #'s i have made up but i believe the temp is a cool 68* in most caves. ...

It really depends on the depth, and the year-round average ambient temp. That is how root cellars function as a refrigerator for latitudes with 4 seasons.

Go deep enough and it will be boiling hot year round, even in the arctic; too shallow, and it's permafrost. Near the equator, it might be a stable 68F 10-20' down.

Geothermal heat exchangers work better in some climates than others.

 

[ToledoEngineer]

It really depends on the depth, and the year-round average ambient temp. That is how root cellars function as a refrigerator for latitudes with 4 seasons.

Go deep enough and it will be boiling hot year round, even in the arctic; too shallow, and it's permafrost. Near the equator, it might be a stable 68F 10-20' down.

Geothermal heat exchangers work better in some climates than others.

It takes quite a depth for the temperature to start going back up. Think about it. What temperature is the water coming out of a 300-400ft well? It's likely 50-55 degrees year round. Now when you start getting near 0.8-1k feet, I think the temp starts to climb back up. Not sure on the exact figures, but I know that the water coming out of deep wells is a pretty decent temp year round. How deep are the aquifiers, and what temperature do they run? Your State DNR could probably tell you.

 

[Demented Guy]

My old army brother built a 12 foot geodesic dome out of scrap water pipe. He dug a 4 foot deep circle and built the dome in the hole. Covered the dome in metal lathe and ferro cemented the outside. Covered the dome with dirt and made a tunnel to get in also out of triangles of pipe and ferrocement. I think the only way it would collapse is with a direct explosion. Also with the bushes and grass it would be damn hard to find.

I want to do the same but think I might use a old manhole cover for the entrance.

 

[joes]

A tunnel out of 55 gallon drum, well that is innovative....Depending on the soil conditions it will be fine in some areas that are dry....The problem that may arise is if a vehicle is driven over where they are buried it could collapse it...In my area I get 55 gallon drums for free and use them for burn pits....I would say stick to the plastic corrugated drain pipe as it is made to take a load...I have 2' diameter drain pipe under my driveway with about 1' of rock and soil on top...I have had a full size loaded concrete truck drive over it several times no problem at all....