Offgrid underground AC follow up video

[@Cornfed_Off-road]

Longer pipe, not larger diameter, longer pipe will allow more time to cool, bigger diameter pipe won't change how much it cools without making it longer

[@shawnd567]

Not true. You just need to calculate surface area. Larger short pipe could have the same surface area and performance of smaller long pipe.

[@Cornfed_Off-road]

@@shawnd567 surface area is important , but think about it like this, a longer smaller pipe allows more air contact with the pipe allowing the heat transfer and the length gives it more time to transfer where a larger pipe will allow more air thru but leaves more air not contacting the pipe to come thru and does not allow the time needed to transfer the heat , yes there is more surface area with a larger pipe but there is a lot of air in the middle of that pipe that isn't making as efficient contact with the pipe so it's not getting cooled or heated as with a smaller tube, same reasons a radiator uses small tubes that run back and fourth inside instead of a lage pipe with some fins, a larger pipe with a significant longer run can increase efficiency. Another example, run water thru a 55 gallon barrel one end to the other with a torch on the side of it and you won't notice much difference but take 50' of 1" tube with the same amount of water going thru it and put a torch on it and it's going to come out hot. Not to mention the slower the water goes the hotter it will get

[@raducumilea-is2yi]

​@@Cornfed_Off-roadyeahhh! It depends the lenth, the diameter and deepest is better. 😉

[@Cornfed_Off-road]

@@raducumilea-is2yi depth it important for constant temperature, too shallow and it will be effected by weather like snow or hot sunny days, from what Ive read at 8'-10' in most soil types is very consistent

[@raducumilea-is2yi]

​@@Cornfed_Off-roadbut i was saying the same thing...

[@Grynslvr2]

Howdy, When I was a kid in the late '50's, our house on the gulf coast of Texas had an attic fan in the central hallway. You opened all the windows in the house, and when you turned on the fan, it sucked outside air in through the windows, and exhausted it through the attic. The hot air which had been trapped in the attic and various interior rooms left the home, and the cooler air from under our shade trees came in. It made things livable, if not comfortable.. The whole idea is to exhaust the hot air, or to exchange the heat in that air outwards. Even my current central air unit takes the heat of our air and exhausts it outside via various steps, in what amounts to a radiator. You cool things through removing heat, not pumping in cool. (cold is the absence of heat, not a force of it's own) Your system merely recirculates the hot air without much thermal exchange.. You might want to consider placing a pair of valves on your exhaust side, on the outside of the building, to make your system an "on demand" open or closed system. The first valve, would be to exhaust the hot air when you want, and the second valve, to intake cooler outside air to go through your pipe, presumably 100 ft. out, and 100 ft. back to replace the exhausted air. Once you get the hot air out and start to draw the heat out of the walls of the interior, you can return to a closed system by returning the valves to their closed positions.. Also, you must move your exhaust as high up as you can get it, and your intake should be fairly low on the wall. Anything else is inefficient. Further, you should have a fan to exhaust the heat and a fan to suck in the air in your underground pipe. This is vital for the "open system" stage of the described dual system. I think that the valves and an extra fan would be much cheaper than re-digging. Lastly, shade, shade, shade. If I had the money, I would build a second roof on my house, maybe a couple of feet above my existing roof, and open on all sides to keep the sun's heat out of my house, so I wouldn't have to exhaust that solar heat in the first place. Just the ramblings of an old man with no more than a high school diploma from five decades ago. My ramblings are probably worth exactly what you paid for them. GRIN Y'all have a great day. Bob

[@darrelljacobjr2120]

A 6" pipe has approx 18.8" circumference. (Diameter x Pi, 3.1415) Two pipes would give you 37.7" total cold dirt surface. (1) 10" pipe will have only 31.4" circumference touching dirt and be danged expensive. To eliminate any possibility of mold in the pipes or water seeping in, just run the pipe out with pex tubing inside. Flood with water, pull water in through the pex tubing, through a couple car radiators, backflow into the corrugated flex pipe. Blow air through the radiators. If you keep the water, level with the radiators, the pump will just be moving the water, not lifting it...more efficient. Get the air intake as far from the exhaust as possible. Insulate the cabin 8" or 12" thick. White EPS styrofoam packing can be salvaged from many a dumpster, shredded in a 55-gallon drum-lawnmower-blender, mixed with a tiny bit of cement and packed into the walls/ roof for insulation. Put some 1/4" foam then stringers on your metal roof, then a second metal roof with eave and (large) peak venting. Or anything to shade the roof and keep the sun from baking you to death.

[@Silver_lad]

Your advice is worth its weight in gold!

[@markr394]

Shade the roof with solar panels

[@markspc1]

Great idea, Dave. I have seen this method multiple times. There is an old man in Nebraska that has done this method for greenhouse and he is very successful. He has several greenhouses running this way. I have few suggestions: make it longer. Also use multiple smaller the pipes. The smaller the pipe the more surface area in contact to the cool earth. So instead of going with a larger diameter pipe, use maybe 4 smaller diameter pipes, maybe 4 or 5 inches. The theory behind this: suppose you have a cube that is 1x1x1 feet. So you have 6 square feet surface area. If you cut the cube in half, you end up with 8 square feet from the same cube. And if you cut it once again you will end up with 10 sq ft, and etc.

[@dtc989]

Nebraska greenhouse guy also buried 1100 feet of pipe buried 8 feet deep...6 inch pipes. It's in one of his videos.

[@dper1112]

You can use smaller pipes, but then you need a lot more of them to get the same amount of air movement, and that drives up the price. As a result, we usually see people using one or two larger tubes... In situations where people really want to use smaller pipes, they tend to use water instead of air, which is also effective but requires some expensive machinery.

[@freddymax5256]

A 12” pipe will have the surface area of three four inch pipes.

[@JohnSutton-gu2kd]

@@dtc989iirc the “Oranges in Nebraska” video (I think) shows 6-8 pipes run together, with ~150 of trench run out then looped back. Velocity through the pipe matters too, slowing it down a bit helps. In a high humidity environment (I’m in Kentucky) I’d be c

[@Tron2pointOh]

It seems like you should put the intake up at the highest point of the interior so it sucks all the hot air that rises into the cooling system.

[@dantronics1682]

He might have made it that way to get more comments, He sounds technical enough to not know that

[@ElementalTJ]

One up high, one down low. Make sure the fans can run in both directions. Then you can use it one direction for cooling, pushing hot air up top out and the other for heating, pulling the hot air up top in. Does that all sound legit ?

[@valerie3955]

Exactly what I was thinking. Outflow should be at the highest point and inflow at the lowest. You'd have to do some finagling with the pipe, but it would probably make a noticeable difference.

[@hottractor1999]

Your goal is to make a person comfortable, not heat up the ground, so it makes sense to cool the air where the person is, and not the ceiling.

[@dantronics1682]

@@hottractor1999 3:30 he said it didnt work

[@timmbot6082]

From what I’ve read about these is you need about 1ft of length per square foot of space. All in all, good job. These experiments are very useful.

[@draaks1]

interesting any sources for that? Trying to plan out a water based system for approx 7500 to 9750 sq ft barn.

[@timmbot6082]

@@draaks1 The info I read pertained to earth-air exchange systems. I imagine eater systems would be more efficient due to water’s energy storage capacity.

[@lorraineclark3876]

Thanks for sharing your experience. Others can pick up where you left off and make adjustments and save a lot of money and time because of you.

[@DNL82]

You could also have run 3 or 4 of the 6-inch pipes into a mainfold setup.

[@uncledavesfrontier6846]

I had thought about that as well.

[@Darkhorseman72]

​@@uncledavesfrontier6846, maybe run the fan as a draw into the cabin instead of the pushing it into the ground.

[@TheRealYorkshireman]

@@uncledavesfrontier6846 fyi smaller diameter pipe has greater surface area to volume ratio so will work as better heat exchange.

[@MrBudcampo]

I’ve got a 40x60x16’ metal shop that I’m going to insulate. I live in TN… thinking of running multiple of these… I’m going to have a 2 acre pond out front, so would be easy to run it at the bottom of the pond instead of digging a ton… From your experience… do you think it would be worth it? Or would it not make much difference? Thanks for the videos!

[@StupidInternetPeople1]

@@MrBudcampoI’d just consider getting a heat pump and just laying coils of pipe at the bottom of the pond after it’s excavated. You’d have heat and aircon in an engineered box with a warranty and save a ton of electric. 😊

[@10esseeTony]

Kudos for making a follow-up video, when things don't quite go as planned.

[@chrischtis2082]

I cant find the first video

[@evansfortune]

@@chrischtis2082it’s 2 years ago

[@advanced-electronic]

The biggest issue that you have is that the feed and return are on the same wall and at the same level. The air comes in the feed and then flows right back out without circulating the room. The feed should come in low on one side of the room because heat rises, then exit the room high to let the heat return back into the system on the other side of the room. This will give a much better cooling effect because heat gathers at the top where it is easier to allow all that hot air to exit. Returning the heat back into the system will still need to be insulated on the outside of the home, not to let outside temps heat the return pipe too much, but it will cool back down in your trench and come back to your home cooled down again. It's always smart to open the doors and windows in the AM to get the home cooled down, then try and maintain the temp. Also, the pipes used should be 100% sealed without perforations to keep the inside of the conduit completely dry. Most folks backfill the trenches with large rocks in their fill which will only crack or break holes in the pipe. If there is moisture in the pipes, you will end up with mold from the moisture.

[@RandomAxeOfKindness]

A couple of people have touched on it, but a higher ratio of surface area to volume will mean better heat transfer. Four 4" pipes side by side will cool more than one 10" pipe even though they have less volume (even combined) because they have more surface area. The surface of the pipe is where heat gets dumped into the dirt. Also, a smooth metal pipe would transfer a lot more heat. If you used 3.25" x 10" stack duct (I make no promises of its suitability, and permanently sealing it would be some work), it would be much more efficient at dumping heat. That's why commercial heat exchangers use a long run of very small conduit. If you have a stream on your property, or a similar consistent water source, creating an overflow reservoir big enough for a heat exchanger can work awfully well, too.

[@snurb48]

Don't bury that galvanized stack pipe, conductor pipe or any other sheet metal ducting! It will rust and cave in or disintegrate in less than 7-14 years! Also recheck your 'Pie" formula for figuring circumference, cubic feet per minute etc. Might be off a little.........ha, lol !

[@K-Effect]

Like the radiator or if you have a turbo a after cooler in your car, it’s made up almost flat pipes with fins to increase surface area.

[@luimackjohnson302]

Amazing! Thank you for sharing this follow-up video. I would suggest that you try a longer run pipes under-ground with one end into a small shelter from the elements, bugs, mosquitos, critters & snakes etc but ensure free flow of air and use charcoal or activated charcoal as filters in series with the air system when air is re-circulated back into your home. In your home you should consider a passive or active system to drawn hot air within the building to above the roof of the building & if done correctly you may not need an active exhaust air pumping to above the roof of the building. Keep in mind that the height of the small shelter where the intake air comes in should be much, much, much lower then the hot air vent above the roof of the building. In-fact you may consider using solar powered exhaust fans if you like. I would also suggest you consider some indoor pot plants & flowers to assist with filtering & fresh oxygen within your home. Greetings from Madang, Papua New Guinea!

[@NextGenerationHealth]

A setup I saw they used 400 feet with several separate loops. Also, others recommend drainage pipe to drain any accumulated water

[@brudo5056]

@ TimelessNews3 … what is theoretical the best location for a drain and where could it be fit in here in this actual situation ? I would expect lower points to be a problem but how to drain those in the actual situation ?

[@watavuemountain481]

Thanx for the whole rundown. We are building a tiny cabin/house and have been considering a similar set up. May have to go bigger or back to the drawing board to find an inexpensive solution. Be Safe!!

[@thatguychris5654]

For a cooling system, this is what I see working for others: - 4 inch pipe works fine, makes turns easily, and you lay it out as a grid in a tight area, instead of one long strand like yours. - 100ft of this 4" pipe should work well for a small bulding. - Make the intake at the highest point and the outlet towards the bottom, shooting upwards at an angle across the room. Helps circulate the cold air and push the hotest up to the intake. - In warmer climates, you lay a second pipe a foot above the first one. This second pipe system has both ends outside and is used during the night / winter (as long as night temp is below your ground temp) to pump outside air into the ground and cooling it further than it could on its own. As cold sinks, the first pipe gets colder and your AC system becomes more efficient. - Make sure to have some holes at the bottom of the pipe section underground to allow condensation to leach into the soil, thus reducing moisture returning to the cabin. It's not about the size of the pipe, but rather the surface area for temp exchange, coupled with making a tighter system for better temperature "storage". Hope this helps.

[@Grynslvr2]

I was mostly with you however, hot air rises because it is lighter than cooler air. "Cold AIR" sinks, not "cold." Cold is the absence of heat in any substance.. I repeat, in any substance be it air or dirt. Empty outer space has NO temperature at all since it has no substance. The absence of heat, in and of itself, does not sink. Again cold AIR sinks, and hot AIR rises. The air in the lower pipe exchanges it's heat into the ground around it, thus heating the dirt by some small amount. The air in the pipe loses heat and becomes cooler. The second pipe might possibly be a heat sink for the ground around it and cooling that dirt, but don't think it would to much for the lower pipe with a foot of dirt between it and the lower pipe. Now a smaller pipe in direct contact with the larger pipe, with an intake for the atmosphere, and a forces exhaust MIGHT do some good in exchanging heat, but probably not much. Sorry, I just can't see the two pipe system working very efficiently.

[@thatguychris5654]

@Grynslvr2 interesting point, but I think you're hung up on the terminology of thermal physics. It is in regular terms for all to grasp the simple concept of pre-cooling the soil before summer heat returns. Soil is a great thermal sink (or void) for such usage and others like mud ovens and rocket stoves, earth ship houses etc. And of course I get the concept of measuring / transfering heat, not the absence of it lol

[@Grynslvr2]

@@thatguychris5654 Howdy. I am starting to think that maybe it is my preconceived notions, based on where I live. I live on an island off the coast of Texas, an overgrown sandbar really. No rocks, no clay, and when I dig a hole in the ground, water weeps into it slowly at about 18 inches, even though I am at 11 feet above sea level. It snows regularly here - about once every 10 or 11 years. As far as I can tell, our two or three months of cool to cold weather, doesn't suck much heat from the ground beyond the first few inches. My water pipes run about 18 inches deep from the city supply line, and they have never frozen since being installed in 1949. All that being said, I am predisposed to think in terms of evacuating heat from air and thereby from buildings. That may work differently in other places. Here the ground is always around 65 degrees or so. I am just looking for ways to reduce my energy bills. Thanks for the friendly reply. Many folks jump down my throat, so it is very much appreciated.

[@thatguychris5654]

@@Grynslvr2 no problem, I love friendly chats regarding science that we can actually do ourselves 😁 Indeed your location is unique. Having water so close to the surface changes things a lot, as does the soil content (all sand). But this could be a good thing if you were to use water instead of air. If the water temp and flow is pretty consistent, perhaps pumping water into a type of radiator, and having a fan on it, would cool enough. If your area has air that is dry enough, even a swamp cooler would be awesome. I even wonder if using a passive cooling system tower with wind, like they do in the desert, would work with you ocean breezes. But you are 100% right, your winters couldn't be used to rob the soil of its heat. I guess I'm biased in that way living in central VA with lots of clay around and decent seasonal temp swings.

[@Grynslvr2]

@@thatguychris5654 Thanks for the response. Sadly our relative humidity runs from a low in winter of about 40% to a high in summer (on days with no rain) in the mid 90% range. I was hoping there was something here for me, but with only a 1/10 th of an acre lot, I just don't see a way to use this really "cool" technology. Sorry, I couldn't resist. Maybe with a bit more room for ground cooling, I could do some good. Oh well, it was in interesting mental exercise. Thanks for playing along.

[@genopsdir]

If you look up a PAHS (Passive Annual Heat Storage) system, they go with a smaller diameter (4”) for a longer run (minimum 200’). A larger diameter will decrease energy transfer for the same energy input. The surface area increases but the internal airflow transfers nothing and wastes energy. A PAHS is a different system altogether but their design seems more sound.

[@jkg6211]

You're 100% correct about the volume to surface area ratio. Also, the intake should be higher in the room, as warmer air will be nearest the ceiling... Thermodynamics 101. He'd get a lot better cooling than just "maintaining" that way - but still, he's got the right idea. Two-story structures? That a different taco to tackle, but doable. ~edit - You're also correct about the length of run... longer = more time for heat transfer.

[@jksuzuki9350]

How about garden hose? Seems a few hundred feet of that means a lot more surface area exposure, the flexibility of the hose means easy to place, and -probably more crush resistant.

[@jkg6211]

@@jksuzuki9350 A Garden Hose would be too small in diameter, and too well insulated as well, for it's diameter/volume ratio... you'd have to run hundreds of feet just to get any significant effect. But you're thinking on the right path.

[@Relaxationdefined8609]

It would cool better if your air that entered came from outside, and the air that exits goes out the highest part of your roof that you can put a pipe or PVC exit. Your pipes come in at only half the height of the cabin. Cool air goes down, hot air rises. Both tubes are at the same height, so the actual heat is still in the cabin from Midway and up. You can't cool captured heat that stays high. Also the cool air should come in at the lowest point, heat exhaust at the highest point, creating a convection pull to naturally suck the air out. Hope this helps. I've done it on my house. It cools 10 to 15 degrees cooler. I only have 1 entrance pipe, 5 ft buried, and 30 ft long. I plan on adding more just for more comfort.

[@kobrapromotions]

Awesome stuff brother, watching from Australia! This stuffs great for our climate and off grid

[@Jeremythagoat]

So I've lived with geo thermal air systems for yrs. My daddy and granddaddy taught Me by making me do the shovel work building theirs 😅. First...ya need a living fish pond small, not very deep but enough to keep water and hence buried pipes being around (not underneath) plus move the intake down lower and the exhaust higher .. I would do that whole place if it was me, up and down stairs. Also ... solar powered fans so you never need to turn air system off. And last .. be alittle creative when Burying the pipe system be sure to work with your environment... shades etc... truly makes difference. Installing insulation and building your roof as living roof (meaning growing something/grass/flowers etc ) will also tremendously help the combination of controlling the air temp. **** and small woodfire burner and or rocket Heater would be plenty to both keep warmth and combat humidity hence mold and mildew just by burning few times off and on if need be. It's not rocket science just got to seriously use some intelligence and listen.... the whole point is to help the earth and co exist living comfortably so paying for ac unit that technology has deamed easy to use but costs out the ass to own run replace then cost of environmental is beyond mentioning.... So A for effort here brother keep at it I got complete confidence you'll get the kinks worked out and there is no one way remember that be creative... like adjusting vent tube's hidden by garden stautes allows for more openings to allow air flow down into the pipping area to either release heat and or draw the cool night air down. Use your Free Will and Forgive and unconditionally love ✌️🫶♾️

[@YeshuaKingMessiah]

Great tips!

[@aesopshair6690]

Good point with the pond... water has a much higher specific heat capacity, meaning it will hold more heat (or cold) for it's volume than earth. Obviously gets a bit more complex when integrating underground water containers, but there are a number of places that use this method for seasonal cooling/heating. 👍👍

[@basilmemories]

A suggestion, if you want to hear it, (and i'll piss off if it's none of my business, you seem to be doing fine without my nosiness), but you might be able to heat/cool even more effectively if you throw a solar chimney into the mix. you take a pretty standard fireplace setup and on one of the outside walls you put in some glass to warm the air inside (if you don't intend to use it as a normal fireplace), or just paint the stones black to absorb heat. also a big point is that the flue lever should vent out at the top, not be at the ground level. Mechanically what this does is create a current of air that constantly pulls the hot air up and out the top of the chimney, and the cool air into the rest of the house. If you put some venting between the first and second floors, and put the solar chimney on the second floor, you could near-passively regulate the entire houses' temps, especially if you put in another earth tube to the outside to bring in more fresh air and avoid making a vacuum. Anyway, great stuff, and hope you're doing well!

[@uncledavesfrontier6846]

I get a lot of what your saying. I found very little research on this prior to building. So it was trial and error. Mostly to see what works and doesnt work for the next cabin im gonna build. It will be a full size hobbit house and i will incorporate a lot of what your saying as far as the stone and fireplace. Ill do a series when i start the hobbit house. Kinda been preoccupied building my food truck. Its almost done and then i can get back to my cabin projects. I have lots of cool builds coming up. I appreciate the feed back and always welcome suggestions.

[@orangezeroalpha]

@@uncledavesfrontier6846 kzbin.info/www/bejne/i6S9mHawaLWEodU Worth a watch. (for the price of large tubes right now, it would be less expensive to get solar panels, a battery and an efficient air conditioner for better performance) I think you need a lot more air flow and a lot more surface area. I've always liked this idea for its simplicity, but there needs to be a better, less expensive way to tunnel air under ground. Thanks for sharing and following up.

[@uncledavesfrontier6846]

@@orangezeroalpha my cabin is solar powered and i do have ac units. I gave this a try to see what the results would be. I enjoy experimenting hoping to find better ways of being off grid. Ultimately i think the best design is an above ground cabin thats buried. Im gonna incorporate a lot of different things on the hobbit house im gonna build.

[@battleofarmageddon1366]

I was just checking on this an i found something interesting. For it too work at maximum potential, it needs to move 5 times the amount of air that is in the room per hour. Hope that helps.

[@uncledavesfrontier6846]

I appreciate that

[@wkmac2]

Your first video on the install of the geothermal system popped up on my feed and I also saw this one on the right and watched as well. Admire people who are willing to think and do outside the box in the off grid space. You just got a new sub.

[@uncledavesfrontier6846]

Thank you very much. Got some cool builds coming up.

[@justaguy-69]

I would suggest a 8 inch pipe running out to a dead end(capped) and another 8 inch running back in that dead ends, parallel in the ground , then run many 2 inch pipes between them so you break the air into smaller pipes increasing its contact (surface area)to the cool pipe walls before returning. like a radiator shape under ground. ribbed pipe would also bring more cool earth into contact with the pipe and air better than smooth walled pipe. Also i would suggest the outgoing vent placed up near the ceiling to pull hottest air out and the incoming vent on opposite wall at mid level to reduce the air being just circled from incoming to outgoing vents without circulating in the entire room. baffles inside the pipe would work good to force the air to linger in the pipe longer as well but it's not easy to do. you could slow the fan also to allow the air to radiate as much heat out as possible before returning.😎

[@thomasmurray4717]

I appreciate you taking the lead on this. Anyone can sit back and take pot shots at you, but it took real nerve to actually put it in service. Thank you.

[@uncledavesfrontier6846]

Thanks for the comment. I ignore the negative people. The world is full of em.

[@shawnr771]

Excellent information. Glad you shared your experience. I know you probably wont add to this system. You might try adjusting the heights of the ducts. Many AC vents are in the ceiling letting the cool air flow downward. Return ducts in old houses were near the floor. Drawing cooler air into the system. The houses you saw in New Mexico are based on Passive Solar designs. Sizing south facing windows with proper shading during the summer time can reduce internal temperatures.

[@YeshuaKingMessiah]

Huge Insulated drapes for high sun months or hours Windows are worst thing for air temp in a bldg Biggest obstacle Literal HOLE in ur wall

[@YeshuaKingMessiah]

Also Deep awnings Cut high sun coming in in summer Allow low winter sun to still come in WinWin

[@casperyourfriendlyghost7552]

Because you have a very low Delta tea, you’re not going to condensate too much but overtime. The pipes will get moldy. It’ll be impossible to clean them out unless if you can run a small amount of ozone through there consistently. To be honest for the time and money, you were going to get much more bang for your buck by installing a radiant barrier on the exterior of your roof

[@CapnRumple]

You should use metal pipe in the ground for better heat transfer & insulate the pipes on the outside where they go out & come back in.

[@uncledavesfrontier6846]

Pipes out of the ground are insulated now and have cement over em. I thought about metal pipe but it doesn't last long. I put one stick in once for a culvert and it literally rusted away in 3 years

[@quantumallure5479]

10" return 6" supply graded and connected to a drum to collect water and use with check valve pump

[@texasprepperprojects]

Great follow up! I think that you can use a 10" 12v DC only radiator fan and save even more energy. Check the CFM ratings (cubic feet per minute). I didn't realize that your cabin was 2 stories tall, that's a very large airspace for only 100' of tube. Great work. I look forward to seeing the next build! (my dad lives not far from you and we talked about this for his wine cellar)

[@uncledavesfrontier6846]

For a wine cellar, this would definitely work great. Another thing i forgot to mention is my cabin outside is metal. So that plays a big difference. Even though my cabin is completely shaded, the metal still adds a lot of heat. But i plan to go over the outside in stone and add some insulation between that. I appreciate you watching.

[@scottbradford192]

@@uncledavesfrontier6846 I think that instead of going to a larger pipe, you should have more length. That way the air has more 'time' to lose it's heat. 200-300ft.

[@uncledavesfrontier6846]

@@scottbradford192 I'm thinking of lots of different things to do on the next build. Longer pipe may be a way I go.

[@khm2128]

@uncledavesfrontier6846, if there is a granite slab showroom near you, or an installer, you could ask if the stuff they throw away is available. Marble or granite may be helpful as a heat sink (if you can crumble that material) above the pipes ☺

[@DannyCreech]

Is it easier to push a cooked spaghetti noodles or is it easier to pull that noodle? Put a fan on there sucking the cool air into the room instead of trying to push 100 feet of air through a six inch pipe. Also, put the air going out of the cabin 12 inches above the floor. The air coming in can be at face hight. Like you said, do not put a 90 degree bend in your pipe right out side the wall. Hope this helps.

[@ytalanwms]

Seems to me that hot air rises so the exhaust should be high.

[@YeshuaKingMessiah]

12” No 12’ if possible Make ur ceilings high like all southern homes used to be with the transom windows over the doors Pull hot out high There’s no hot air on or near floor Blow cold in high and it will fall down, cooling as it goes

[@HVACGUY]

Nice follow up. Mildew should never be a problem as long as pipes are sealed. It doesn’t produce moisture, and it’s drawing air from inside.

[@billsmithingell7902]

Moisture would come from the air condensing as it is cooled inside the buried pipe.

[@jereomemoore7269]

Not true. This man lives in Texas which has damned near 100% humidity all year round.

[@xungngo]

moisture from the humidity is the major issue people don't do this. to do it they make sure there is a way to address the mold issue from condensation, which occurs and you don't even know it. dehumidify inlet with desiccant (not at outlet because somewhere in the middle is where condensation/mold begins), provide slope for maintenance, slope for outlet, good ventilation(a fan) in front of the outlet, and a solar chimney to increase air flow.

[@mindofmadness5593]

@@xungngo I'm from Texas but live in N.C. now, also very humid. The thing that is stumping me is setting up some sort of condensation removal system when the pipes are eight feet underground. Here my water table sems to be around four feet according to the critter grabes I've dig but even at fur, any sort of condensation cleanout seems problematic.

[@zombieblaster5754]

I think one of your issues is the even input and output. you need to have a vent at the top of a wall and one at the bottom somewhere else. you are just creating a loop with your current setup where the other way would circulate the air and use its own hot/cold physics to help move it. another thought is to have the hot going in on one side of the room and the cold on the opposite so that the air has to travel through more of the room therefore transferring more heat and maybe reducing draft? there are several insulating options that may help as well for transference of the pipe outside. you could also use a water loop as water transfers heat energy much much better than air. with water you could also use radiators to effectively dump the cold somewhere. an extension on that thought, have a radiator at the bottom of a wall and another at the top to collect heat better. as far as where to get radiators if you really want something cheap you could probably go to a junk yard and get a bunch from cars, the caveat being that you would have to find a way to connect them all. the huge downside of water is the chance to freeze so it would possibly have to go deeper which will cost more but water pipes are cheapers usually so the cost/effectiveness may or may not even out. if you used a solar heater for water that could help with heat and circulation during winter though I guess you could do this with air as well by making a big black box on your roof to collect the sun.

[@WalterPidgeonsForge]

Air is not the best conductor of thermal energy.. which is why liquids are used.. You could have buried a few coils of 1” pipe and put a couple recycled hot water radiators in series and gotten a much better return on your work. (Needs a solar pump and drain pans under the radiators.. makes nice clean condensate).. in your design, Condensation in that buried pipe can collect in the corrugations and grow pretty toxic molds.. ideally a pipe which has a smooth inner bore, but also metallic spikes through it to engage the thermal mass of the earth and transfer that heat into the passing air.. I melted large landscape nails into 4” PVC which worked well (if you look in a gas home furnace, it uses a similar concept to heat air).. and it requires a condensate drain as well.. which you can add with some second hand goretex from Goodwill and a little gravel. Larger diameter pipe mean you need a larger blower and corrugated pipe is really restrictive The systems like you have built work in the Southwest because the humidity is so low and the overnight temp usually drops dramatically … This is just information that may help anyone going forward.. Your videos on this have been great. This is not a criticism at all of what you have done.. making good content. 👏👏👏👍

[@YeshuaKingMessiah]

Ahhhhh SW only Deep South would have mildew probs for sure! My books in outside storage waterproof unit are mildewing 😳

[@thopkins2814]

Definitely a great idea. Have you considered using a fan on both holes? (One hole blows air in and the other blows it out).

[@chrischtis2082]

my first thought

[@TinyGoHomes]

You will need to allow for the ground to cool at your areas max low temp like winter time I think before you get an accurate test. Probably take some time for the ground to cool down after unearthing it.

[@learner-long-life]

Great work, inspiring to see. If you keep consistent airflow, I think that should reduce mold spores from settling. I'm not sure about mildew, maybe if there's a lot of humidity and it condenses and settles in the tubes.

[@uncledavesfrontier6846]

I run a dehumidifier in my cabin.

[@condew6103]

I think the underground loop being air and water tight is important to avoid mold and radon, so I'd go with multiple loops of 6". I'd also insulate the section from where it leaves the ground to where it enters the cabin, looks like a lot of the cool will be lost in that run, especially if it's where the sun can hit it.

[@uncledavesfrontier6846]

@@condew6103 pipes on top are covered now.

[@driverguy7]

This is excellent work and also for you to share the honest results of the project. 1) I would try insulating the "outgoing" black tube, just in case its picking up solar radiation and reducing the efficiency of the system. 2) Could you put a relay in the electronic control system so that it cycles off and on like a car's air conditioning unit? Have a good week !

[@JohnSmith-qd1qm]

This really is genius. Thanks for the update

[@uncledavesfrontier6846]

Thanks buddy

[@Nova-m8d]

Heat rises so the air at the ceiling is 50% hotter than where you have the air inlet located on the wall. Insulation in the walls ceiling and floor are major factors.

[@dozensides]

Uncle Daves Frontier: Hey, Dave! I think that if I left the cabin in the early morning while it was cool and came back mid-to- late morning after a walk, I'd be happy with it maintaining my earlier cool temperature. I managed to get a 1 degree drop in temperature with four-inch pipe by running it into and out of an empty 5-gallon water bottle. The air gets stalled momentarily while a small vent hole at the top of the bottle allows heat to rise out of my system. The rest of the air passes on along the run. That was a one degree drop using only one water bottle and about ten feet of 4-inch pipe. I had planned on using a narrow tube at the top of the 5-gallon bottle to get that heat out to the surface straight up. My test was not buried on a finished system either, so the results could be a little better or variable to say the least.

[@mosbysmen]

have one blower on the intake and one blower on the exhaust , make one with a 12 volt fan and run it on a solar panel all day .

[@vociferonheraldofthewinter2284]

I live in Arizona and honestly, maintaining temperature on 1/10th of an amp sounds damn good to me. Our household AC unit struggles to even do that when it's crazy hot in the summer. And we're paying $400 a month for it to try. smh

[@zombieblaster5754]

well the A/C fights the heat while the ground just evens it out so if youre in arizona I would suggest doing this. all you need is some pipe and a shovel. you can also use water, but that can freeze.

[@mindofmadness5593]

Had a Swamp Cooler in Sedona [[Not feasible here in NC die to humidity]] Kept the place liveable during the day and darn cold at night.

[@mike4769]

Those earth houses also have vents up high that suck the heat out naturally. Maybe there is a way to put the return at a high point so the airflow will pull out the heat more efficiently. I'm looking to build a similar system. Thank you for sharing.

[@PeterLawton]

I like this idea. Since warm rises and you have two stories, I think I'd make the next upgrade to draw air from the highest part of the second story room. A higher temp going into the tube will mean greater heat transfer to the earth.

[@bradjon7231]

I think if you moved your intake/suction side higher, perhaps 7ft high, your air into the house at 4ft high you may see better performance. Im thinking your are recycling your cool air rather than removing you hot air.

[@palewine]

You'll get better heat exchange by multiple smaller pipes, as opposed to one larger pipe. Smaller pipes have more surface area (per air volume) to exchange heat from the air to the ground around it.

[@JSabh]

Do two tens, one for up stairs and downstairs. Also, run a duct across the ceiling and wall with two 5 inch outlets for each to even out the flow. It will cool, you just need to get the airflow and air dispersion even and strong enough to move the air.

[@dragondack]

With bigger fans, there will be less time to transfer heat. You might need significantly more pipe.

[@seewaage]

I really like the awesome project! I hope you can figure out how to get it to work optimally.

[@GoldFishBoy1337]

could you run 2 / 6"pipe side by side? Hot air rises have in intake fan in the ceiling and the cold air return in the floor. Love your video. Kevin

[@uncledavesfrontier6846]

Good idea

[@barebooger]

As an experiment, please try a larger fan. I think the BTUs are there, you just need to move more air.

[@davej7458]

Consider multiple six inch pipes. More resistance for the air flow, but also more surface area. So the heat exchange should be improved. I know there is a mathematical way of comparing those differences, but it's not something I know. Also, space the pipes apart, and the heat will transfer more efficiently. As the summer goes on, does the temperature differential between In going and out going air remain about the same?

[@invisiblemiles]

Thank you for sharing this info. Beautiful accent ❤

[@christopherm.esparza705]

Love the idea. I think if you used a 12” metal culvert you’d get better flow and cooling conduction.

[@spiceyweasel]

Try this: Build an underground chamber that pulls cool air into your place near the floor and put a dome ceiling with a fan that exhausts hot air out the top of your home. I noticed our basement was always cool year round, so we put fanned vents between the first floor and basement that pulled that cool air up from the basement, then vented the ceiling to draw the hot air out and our cooling bill plummeted. We reverse the fans in the floor in the cold months to warm the basement.

[@ArtistBrianSheffield]

8 ft depth minimum for pipe. Even at 100f outside it can keep it at around 72f inside if the pipe is long enough. Those earth houses in new Mexico use this. Also some greenhouse. You still need a way to force airflow though.

[@johncoaleii1423]

Two suggestions. One option is increase the surface area of your pipe. The more surface area the more efficient. This can be achieved by increasing length and increasing your cfm. The other option is run with a pex type pipe and reservoir. The fluid circulatef via pump through the pipe carries a lot more thermal mass. Inside your home attatch to literal radiators with a small fan. The radiator of course has an incredible amount of surface area to radiate heat from. Ive thought about doing something such as this myself. I have a greenhouse, polebarn and of course home. I dug a 3/4 acre pond this year and this idea can be adapted using your pond as the the thermal mass and reservoir. My home has a very high water table which works to my benefit. If i go below four feet im around 55 degrees but because that constant water comes in contact with the pipe i should get more efficient exchange and a constant temp. It really amazes me this isnt as well known or put into use. We have this transition to a green world and the reality is all the tech is as far from green as possible. In theory every home in the world has access to all the energy it needs under the footprint of the property. I appreciate your short videos and keeping it simple. So many people go on and on. PS what would happen if you took say a 12 or 15 inch pipe at the inlet and underground go into a manifold that say branches four 6 inch holes. Then run 600-800 feet. After the loop go back into a manifold and your outlet re enter with a 12 or 15. The reality is this massively increases surface area and lengthening means a longer distance to exchange energy or force more air through the system . The result would allow you to overcome and actually lower vs keep a constant temp. The other option might be after your manifold to push your air to variaous vent ducts instead of a singular. You're getting close. I love figuring out this stuff and love trying to cheat the system for as cheap as possible 😂

[@uncledavesfrontier6846]

I have some other ideas I'm gonna try. I appreciate the feedback.

[@hermanclarke283]

Build a insulated box around the pipe where it is piped into the cabin

[@james10739]

About the mildew I guess the real problem is inside the pipe condensation will condense and no way to get it out

[@stevepailet8258]

you have the right idea One big error is that you need more pipes in the ground. Also if you can find a DC fan slow the spped. for each tube that you bury figure 6000 BTU of cooling. So you likely need 3 more tubes.. bury them atleast 6 ft apart so you dont suck heat or cooling from the pipes being to close together 6 inch is more than enough size going with larger pipe will only remove heat from the soil faster and will take more time to recharge

[@felonebike9859]

Appreciate your honesty

[@MM-fe9mz]

I think maybe a bigger or multiple intakes from the cabin to a bigger fan pushing air into the 6inch pipe would make this alot more functional.

[@mattfrownfelter558]

Maybe put the intake and output on opposite sides of the building? Create some draw across the room?

[@kludgescraftsplus8631]

There are a number of things that can be done to improve the efficiencies. Yes a longer pipe not a larger one, also gently sweeping arcs as opposed to long straight runs that hit 90s. In a long straight run you will have a boundary layer between the center flow and the wall of the pipe. Especially this ridged pipe which will have a turbulent layer of air. I would also question whether or not the midpoint of your loop should be lower than the rest to encourage any condensation that forms to drain away. This point could be placed to be accessible in a hole. This would allow you to ensure the water removal with visual inspections. There are some really good videos on greenhouse cultivation in winter climates using this exact type of loop for climate control.

[@williambixby3785]

I would think that if heat rises the outlet should be higher to pull the hot air out and cool it off and maybe have a lower outlet? Possibly a fan on the outlet would help as well… I’ll let you know when I try it lol

[@Buffenmeyer]

Have you considered an intermittent fan that would pull fresh air into the pipe then stop for a few minutes to let the underground air cool down. Then maybe after a few minutes the fan activates pulling a new volume of air underground, then stops, etc. I would think this would give the circulating air a chance to reach cooler temps.

[@tommymadux3646]

Also move the intake across the room. So it moves more air around.

[@blitzegron4848]

You need more surface area in contact with the ground. Also the corrugation of the pipe impedes the volume of air. I think it better a liquid system similar to radiant floor but use a radiator.

[@OceanOstteen-ky2gv]

Have you considered placing the outgoing port up high to gather the hot air?

[@TooTrue1874]

Maybe just use more than one 6" and place the intake hose higher up and the exhaust hose lower to the ground. That way it gets the hottest air at the top of the room to mix with the cold in the pipe. I think it would be cool if you got a fan that can move more air too. It might not be worth it with a 6" pipe but I'm curious if a much larger fan could make a 99° room comfortable in a 20-30 min timeframe.

[@misterp158]

Build a liquid closed loop with some sort of antifreeze and a heat exchanger/radiator. You can use an efficient pump and just use the same fan you are using. At least spend the extra money now while you have your hole and bury some piping for future use.

[@uncledavesfrontier6846]

I'm doin that on my next build. I'm building a hobbit house next to my pond. I'll run the coils to the deep end of my pond and back to a radiator.

[@misterp158]

I hear you. Good Idea. Thanks for sharing@@uncledavesfrontier6846

[@scytaleghola5969]

OK I was going to suggest a manifold, but I see others got there before me. Make sure the volume of air in the manifold is several times larger than the source pipe. This will cause the air to contact the cooling surface for longer and improve efficiency. Also, put the fan outside and blow into the system. This will reduce the noise some, inside the cabin.

[@uncledavesfrontier6846]

That's my fault. I had the mic sensitivity turned up too much. It's actually really quiet.

[@davejalenderki]

Put your exhaust close to the ceiling and your supply close to the floor. It will remove the hottest air from your home and exchange the heat into the ground. Use longer tubes for more heat exchange.

[@MalleusDei275]

Have you considered a passive evaporation cooler. Low humidity, high heat.... The temperature deferential will drive the exchange....

[@MrThrock09]

3×6 inch wastewater flexible nonporous piping works perfectly. You need 100 feet out and 100 feedback so 200 foot when it’s 90° out you’ll be blowing 55° air into the room and a bigger fans a good idea.

[@AndreiBanciu]

A system that starts/ends with a 6" pipe, then splits in the ground to 2x4" loops has the same surface area contact with earth as a single 8" loop. It might work out better this way, as you'll get pipes in longer lengths and you won't have to dig such a wide trench, you might be able to dig a narrower and deeper one, and burry the 2 loops one of top of the other, say 2 ft apart. The volume of air inside the pipes is double in a 8" pipe compared to 2x4", that means for the same surface area with the ground you will have less heat exchange in a 8" system, so better cooling with a 2x4" system.

[@chiefjoseph8154]

In the late 60’s I discovered buried culvert pipes in the rear of a barn. They were deep in the huge manure pile. Could this have been some sort or heat source coming off decaying manure at one time?

[@ForestToFarm]

I would guess it was. People do a similar set up with composting to gain heat. Terry

[@SteveWB]

I always wanted to bury a long pipe like you did but pump water through it into a car radiator. Then use a fan to blow thriugh the radiator to cool the room. Or put it in front of your current ac intake to pre cool the inbound air.

[@uncledavesfrontier6846]

I could see that working

[@UGoPoundSand]

It works awesome. Even just a couple of feet down cooling is remarkable

[@stephencarr2697]

With restriction of 6", the only resolve, is to increase air flow. Unless.you cut the furthest section& make the two 6" pipes both returns,& your intake shielded from direct heat. Rearrangement of existing structure, minimizing work done.of trenching,& upgrading.you want bigger exchange. Volume air flow. The intake could be like a ac condenser- a water cooled tubing chamber, like radiator. Bulk of water could be a underground water reservoir, maintaining temperature intake.via a circulation pump,manual thermostatically controlled, as per heat of the day. Yet adjustable. Great work. Good luck. With variables.

[@raffly4449]

I suggest a fan at both the intake and the exhaust. Muffin fans are horrible at moving air against any restriction at all. I’ve successfully cooled high power electronics using a fan at both intake and exhaust of an enclosed space.

[@stevedickson4744]

keeping an insulated space above freezing and below boiling would be workable using this method for a lot of locations.

[@seanbarrett657]

If you're gonna have to split the pipe anyway, would there be any benefit to going 8" - 10" underground and 6" coming in? Also maybe a slower fan? The idea being you would give the air more time underground.

[@JesseChoupique]

How do you get rid of the condensate in the pipe? also, can you put a temp gun at the exhaust and see the actual air temperature?

[@uncledavesfrontier6846]

I have a dehumidifier in the room. It's never humid in my cabin. If you didn't want to go that route, use the pipe with holes in it and lay it on gravel before you bury it. But I've had no issues with any of that. No smell, no mold, no mustiness.

[@ericdpeerik3928]

You need your inlet low on the wall and your outlet high up where the warm air is.

[@A1986Ge1995]

A couple of questions is the fan pulling the air trough the pipe or is pushing it? I ask this because I remember watching a video posted by someone that had built a earth battery system to heat/coll a greenhouse and he experimented with the direction of the fan and he stated that he had better results by pulling the air trough the pipe rather than pushing it trough. The other question? could you insulate the part of the pipe exposed to the ambient temperature? it might make a difference. Just my two cents.

[@uncledavesfrontier6846]

I use an exhaust fan pulling the air. Pipes that are exposed are insulated. Didn't get a change to show it. Still had a cement job to do around it

[@Greenr0]

The reason why the house is not cooling down is because you don't have an attic fan to pull hot air out. Run an attic fan as well as the underground pipe fan then you will see a difference. Also, instead of putting 10 inch pipe down the tunnel, you can spend the time and money to build an outside shell, at least a foot away around the cabin instead. Air's R value is 3.6 per inch. One ft will have 43.

[@weareone7315]

I’ve thought of putting a 2 x 4 foot aluminium box under ground where the tubing runs in and out of

[@djdynieldaniel1395]

If I go with geothermal. I'm considering a cosed loop. 3/4 or 1 inch plastic pipe witch either water or antifreeze and a car radiator.

[@jasonmartindale3171]

I'm no engineer, but based on some of the other videos and information I've seen and read, the "mildew" concern may have been misconveyed. If your pipe system is continuous, the warm air entering will create condensation when it meets the cooler pipe surface which eventually could produce standing water in the pipes. To combat this possibility, your pipes should have at least a 1% grade to a sump well with a pump.

[@billybass6419]

Could you get a "Y" connector and run 2 runs of 6 inch pipe still with a 6" fan? Might there be some metal pipe, like thin aluminum, that would transfer heat better than plastic?

[@GreenKizurra]

Dang. Its soounded good. What about making more pipes . More the cooler the air going in. Or at the end of the pipe in the house have a blower and evaporator there. I don't know.

[@redcloud870]

Thanks for this video. Good information!

[@tomoverholt5123]

Couple thoughts, your 2 pipes are too close, the cold air probably just stays there. Pipes with seams will almost surely leak which will cause mold. Just add more pipes, I think it will work great.

[@geoffsmith82]

Several things. I would wouldn't have the vents at the same height. I would have one down low and one up high. To cool the place I would suck the air from up high and push it out down low. I would use a larger fan that is downsizes to the pipe size. A larger fan can run slower and thereby be quieter. Add extra pipes to get more contact with ground - longer pipes would require the fan to push harder. This will allow the pipe to actually cool the building instead of just maintaining the temperature, when turned on.

[@gregory4154]

This is still thinking outside the box. Not bad. Like any idea or system, it just needs refinement to improve it.

[@MPTX-be8qq]

What it you put the exhaust higher up and the air coming in lower to the floor? So that the hotter air is being sucked in and the cooler air near the floor would be coming in.

[@Velocentric]

Good experiment. The idea is to maximize the time and surface area of the air molecules against the pipe wall. IMO 100' seems too short and 6" diameter too big. The fan speed may also be too fast. Most of the air flow is plowing through the center of the pipe not touching the walls at best, maybe interacting with the stuck boundary layer on the wall. If you are not measuring between 50 and 60 F coming out of the inlet then modification is in order. I'd bury a couple of hundred feet of 4" corrugated drain tile at least 10' down and adjust fan speed untill I got the lowest output temp. The tubing can be coiled in a hole to save on digging.

[@grumpygrandpasgarage]

Use a smaller diameter longer run smaller dematerialised , moresurface area for heat exchange

[@WTF_BBQ]

I've always wondered about Mold growing in the pipes with these types of geothermal cooling. I guess flooding it with ozone from time to time could keep it clean. Just have to make sure not to breathe the gas.......

[@kleingarrett55]

Would be interesting to see if the air is just being sucked over to the inlet since the inlet and outlet are so close. Also would be interesting if the inlet was close to the ceiling and the outlet was at floor level to suck out the hottest air.

[@uncledavesfrontier6846]

I'd do a few things different. I'm gonna change a few things up on the next build.