DIY Geothermal Greenhouse Part 7: Earth Battery MISTAKE!

#116 After starting to build our DIY EMT electrical metal conduit (1.25") greenhouse two years ago, we are finally back to completing this project.
We readily admit we are not experts at this (we are not engineers, greenhouse experts, or thermodynamic scientists), but a family doing our best to do it all ourselves and install based on all that we have read or watched on KZbin (don't believe everything you see on the internet) to date and in line with our limited budget. Based on comments on videos, we already know some things should be done differently. Hopefully, it still works well enough, even if not optimally. We plan to share the results regardless.
In this video we must admit a mistake and correct it. The supply, return, and manifold originally installed were too small. So we're fixing that and trying to do a better job of explaining the whole system.
Background on the project: Our farm homestead came with metal pipes in the ground from a former 16' x 50' hoop house. It also had water lines run from the farm well (which also needed to be restored) and a 60 amp electric service. In the first video we installed the 1.25" EMT conduit that serves as the frame. In future videos we'll frame the end walls, run electric, and get the plastic cover on in time for winter.
Each rib or section of the greenhouse consists of three 10' pipes, no cutting. They are joined by stock EMT connectors. The two outer angles are 117.3. The ridge angle is 125.4. Sides are 6' tall. Just over 10' to the ridge. 16' wide.
Ultimately, this will be a double wall plastic film greenhouse.
+AMDG
Music
Jason Shaw: "Landra's Dream" goo.gl/pi68XB
#greenhouse
#passivesolargreenhouse
#emtgreenhouse
#earthbattery

[@DebiB62]

Kudos to you for being willing to share not just your successes but your mistakes as well so that we can learn from them and not have to make them ourselves. Thank you!!

[@user-li5br8in6z]

Thanks for posting. We are at the point of adding the drains and now we know to go buy bigger pipe before we start

[@grundegrimstad4703]

I love you for including mistakes like this. We´re all here to learn. Your video series is a really big help in planning and designing my own future greenhouse project. Thanks!

[@thomasfeiller2207]

He's almost right.... Let's say you have six 4" pipes. That's 12.57 sqin per pipe with a total of 75.4 sqr inches. The manifold should be equal to or greater than that in order to have a consistent volume between the manifold and the pipes connected to it and to prevent back pressure on the fan. A 6" inch pipe is 28.27 sqr inches... this is less than half that is needed. A 10" pipe has an area of 78.65 sqr in. A 10" pipe is needed for the manifold using reducing tees to connect to the recirculation pipes. The formula to us is pi*radius*radius. Having said that, since he is using an undersized fan for six 4" pipe he can get away with a smaller manifold. My point is that ALL components have to make sense as far as volume(based on area of opening or cross section). A 10" fan to feed a 10" manifold to feed the six 4" pipes that he buried.

[@tekmouse]

Holy cow. That works great! I did not expect to see it drop 60+ degrees!

[@amberolivarez9047]

Thank you so much for your family's time in making these videos!

[@ChickaWoofRanch]

Glad you caught it now and got it corrected. Thanks for sharing! Very interesting

[@StIsidoresFarm]

Yes, it's one of those things that would have nagged at us every time we went in the greenhouse. Best to just stop and deal with it now.

[@stonefieldyhh]

I appreciate you sharing all that hard earned information and willing to reflect and improve the system. Please keep us posted regularly. Subscribed. Thank you.

[@StIsidoresFarm]

Thanks. We've made huge progress this week, so Monday's video should be a good one. And yes, we plan to continue updating about the greenhouse and sharing data about how it is functioning - but hopefully you'll stick with us as we continued to upload about our random projects and adventures on the farm.

[@joansmith3492]

I am going to build a small greenhouse this summer with a climate battery. This helps me tremendously. Thank you! I look forward to seeing your progress!

[@StIsidoresFarm]

Great! We're glad it could be of help!

[@yobrowtf6674]

Good man- well done. This is how we all learn, thanks.

[@sjvche7675]

You really should use thermocouples to measure the air temps. The IR units are best for surface temp. readings. The plastic pipe surface that IR's read is slow to heat up or cool down, because they are plastic and thick. Wishing you success.

[@arebuffat]

Sir, I ended up here a bit by chance and I'd like to congratulate you and your family for all the hard work you're putting together on doing these videos. thanks a lot for sharing with us all the infos, including your mistakes and the achievement.

[@StIsidoresFarm]

Thank you for watching and taking the time to share your kind words. Blessings to you and yours.

[@ahowl7mx]

I learned a lot from your video. Sometimes the fails are just as good to know as what works. Keep it up! I'd like to see the final greenhouse in action.

[@StIsidoresFarm]

Thanks for the feedback. We're steady on it now. Monday's upload "should" show a mostly finished greenhouse (we hope).

[@Anthony_DP]

Sucks dude! I can't believe I missed that too! Always the little things... Glad to see you mentioned DC over AC for the fans. Thanks again for sharing

[@StIsidoresFarm]

Thanks - suppose it could have been worse. Just glad some folks took the time to share wisdom and offer critique. Got the fans up today and the system complete, but with 12+ hours of rain and 98% humidity it did nothing to run them. So we're looking forward to the next day of warmer weather to test it out.

[@LampWaters]

Nice video. Humility is grace :)

[@Christian-bc2es]

Thanks for the detailed explanation.

[@StIsidoresFarm]

Our pleasure - thanks for the feedback. We were worried it was too much explanation.

[@davidbradford2897]

Great stuff. Thanks for the video.

[@Mrsnufleupagus]

That was awesome! I am a fairly new sub and have really been interested in your build. I read the comments you were talking about and it made me wonder. Thank you for showing and explaining mistakes. It is infinitely helpful for those of us looking into this type of system. A bit of humility sure goes a long way!! All the best:))

[@StIsidoresFarm]

Thanks for the support via comment. We do appreciate it. Our hope is to always show the good, bad, and ugly of our adventures out here. And we certainly have no interest in putting something out there that is wrong. Just wish we had learned a bit more about this before we had to spend three full days fixing a mistake! But yes, humility goes a long way. Thanks for subbing!

[@thegardenfarmer]

Great update. Progress is progress. Good thing you went with the higher cfm fan, as that corrugated pipe will create quite a bit of static pressure.

[@StIsidoresFarm]

Thanks! We're learning a lot. This is test greenhouse. We'll be building a much larger one nearby and hope to make improvements and modifications based on what we learn with this one. "Progress is progress" - great quote.

[@curtisavery4504]

Thank you for your information and the sources!

[@StIsidoresFarm]

Our pleasure!

[@Matty.B]

Thank you. Thank you. Thank you. Great info. Great explanation. Oh, and thanks!

[@AgeBeforeUgly]

Great job so far, can't wait to catch the updates, hopefully with plenty of data / numbers to share about how well it works with day to day usage! Your videos are a big help to all who are planning on trying out something similar. Personally, I need to come up with something slightly different, more of a heat sink for that endless Texan summer, but seeing clearly how you are doing things here and hopefully in the future seeing the results will be a huge help. Glad you caught the error before it was too late. These things are too costly and time consuming to invest in, only to find out you made an error, after the fact. :)

[@StIsidoresFarm]

Thanks! Yes, I suspect different systems would be needed in different parts of the country, especially in Texas where you wouldn't have to contend with cold as much as heat. And yes, now that we're done with several days of digging and fixing - we're very glad we did it.

[@garethroberts7932]

Very informative, thank you! I'm always (not initially, mind you) sort of glad when I make mistakes because it does give you the opportunity to learn where you went wrong and gain a little more knowledge. At least you had a relatively easy fix. Carry on!

[@StIsidoresFarm]

Couldn't agree more. Better in ways to make a mistake and learn, than have dumb luck and not really know why something worked.

[@garethroberts7932]

St. Isidore's Farm . Absolutely. We have a saying on our land, 'hopefully we make mistakes'.

[@tommysanfilippo3165]

Mine saying is we do it right cause we do it twice. Lol

[@karlInSanDiego]

I applaud your efforts and look forward to seeing how it works out for you. We have a 350 sq-ft glass house and installed a slightly more primitive version of what you've built (using a barrel plenum, your exact fan mounted inside the plenum so it's quiet, and spaghetti tube configuration instead of a linear array). We used gravel around the pipes to discourage rodents from tunneling into the system. Our experience has shown that for cooling a greenhouse, circulation followed by ridge ventilation is key. Before we added two healthy circulation fans in a raceway orientation, our raised beds and the plants were getting fried and there were loads of hotspots. The circulation excites all the pockets of hot and they rise through passive vents and an exhaust fan. Our SCHS is capable of pushing out about a 10 degree differential for several hours before temps equalize and it loses its efficacy. So we time it so it operates starting at the hottest hours of the day. We chose to cool the lower air, and not pull hot air from the ridge, because that air is destined to leave anyway and there is no benefit grabbing the hottest stuff. Instead, we pull a single intake about a foot off the ground, and let our circulation fans equalize the lower height temps. Our exhaust from the system is coming out in 6 evenly distributed floor grates, so cool air is put where it might serve the best counter effect to the heat (and below our raised beds). Then in the middle of the night, when heat is preferred (San Diego has cool nights year round) we run for a few hours, thus cooling the ground (discharging the climate battery). The overall effect of our system is a nice equalizing factor that helps minimize overly hot days (in conjunction with circ, exhaust fan, and foggers) and minimize swing of coolness at night. Finally, because we wanted to conserve water, our raised beds are subsoil irrigation beds. I integrated all of the water lines with a common reservoir, and this allows periodic circulation of the water, which also helps stabilize temperatures, and this winter I threw in a 100W aquarium heater to help a little with heating beds through warm water beneath the soil.

[@StIsidoresFarm]

Sounds like a great system! Any chance you would ever consider uploading a video about it?

[@alexferguson3680]

St. Isidore's Farm that would be awesome

[@yossarianmnichols9641]

Come on now, San Diego needs a thermal battery? What is your 25 year low temperature for one hour? 50 degrees

[@fallingrockhobbyfarm1210]

I would love a copy of this video...im building a green house and every1's questioning about heat I live in VA. TIA

[@InTuGuru]

Excellent information!

[@StIsidoresFarm]

Thank you and God bless!

[@mann5353]

Nice work..

[@DarnWhippets]

Some of the best info available. Great real world fix. Thank you for the vid.

[@StIsidoresFarm]

Thanks for the kind words and for taking the time to comment and support us!

[@DarnWhippets]

I'm impressed with the temp drop through the battery in the day time. It's way more than I imagined from the system. Can't wait to see how much heat is given back.

[@harmonysalem9377]

Merci from Montreal, Canada.

[@pms1953]

Love these video.

[@chefboyrdanbh]

Awesome! Thanks

[@MultiOhioman]

Thank you.

[@speedbuggy16v]

Thanks for sharing the mistakes as well as the gains, I am thinking about doing the same as this for my greenhouse. Now I have not done as much research as you, but there are so many variables to consider its not even funny, there is airflow, there is thermal conductivity in comparison to flow, speed and area of your essentially , condenser, then all those variables in relationship to the size and efficiency of the greenhouse. I am sure some engineer somewhere would know exactly what questions to ask and be able to give an answer, but each variable even up to type of soil would change it. So I will probably just follow your lead, and it ought be be "close enough for govt. work". Thanks for sharing!

[@StIsidoresFarm]

Unless you're getting ready to build it ASAP, I'd wait for us to share data and make design recommendations/adjustments. We've learned a LOT from the comments on our videos and would certainly do some things differently. Of course money was and is and issue.

[@speedbuggy16v]

I am always in the middle of a project, so it may be a bit further down the line before I get anything started, but if not, I think the ideas you have are still good, especially with the feedback your getting. In the end a greenhouse is good, and any improvements you make are better, may they be the ideal, most efficient? Maybe not, but its still an improvement.

[@thegreenviking1422]

love this video series.. learning allot thanx for sharing.

[@StIsidoresFarm]

Thanks for the feedback!

[@JoeZyzyx]

Maybe passive air flow? Black chimney to accomplish it? I knew a neighbor who got tired of waiting for his flue to warm up when using woodstove, so he painted it back, and then it always had draw available without worrying about smoke intrusion before the flue warmed. He had an opening at bottom he could push a rod to let it draw from outside when not burning woodstove, but close on cold days and the sun created warm chimney and good draw for the immediate starting of the stove.

[@sergiimelnikov9374]

Fair and square!

[@Keepthefaith387]

I have been looking at lots of videos on green houses and like yours. I actually just finished completing a SHCS in a small 12 ft x 12 ft green house. Wish there were more videos. I am trying to figure out how to manage the system especially on hot days where the green house can get over 100 deg and cold nights where it can get below freezing during certian times of the year here in WY

[@gsmscrazycanuck9814]

I was thinking the same thing, but wanted to see how you made out. My system would mimic a in floor heating system with 200' loops instead of a manifold.

[@joepeeer4830]

Ty

[@nikyrios]

Gracias, era exactamente la información que estaba buscando, Yo quiero usarla al contrario que ustedes, Para enfriar un espacio. Y usar una bomba de vacío pasiva apartir de una chimenea calentada por la energía del Sol. Saludos desde los Cabos México.

[@51rwyatt]

One of the things I struggle with these ideas, is the sheer BTU issue. Even really good geothermal systems in tight home construction have limits. In an uninsulated greenhouse, the problem of getting the volume of BTUs needed to materially impact the internal temp versus just a plain greenhouse... I'm skeptical and I haven't seen a lot of quantitative results other than folks just being excited about certain methods and undertaking the builds.

[@jimh712]

My thoughts in theory... Would be to have a larger manifold coming right off the fan equally distributed to the buried grid.. Slowing down air flow thru all the tubes trying to balance the air flow.. Giving time to enhance the heat exchange.. My thoughts are, to high of an air flow speed could heat the air because of friction... But when i set up my testing I will try to record as much info as possible... My first green house won't be the most efficient... But will be my testing center... and after testing each individual grid.. When tied together should be give the desired results..and much needed testing..

[@grasso7200]

Omg man that's incredible! An 80 degree drop? Insane!

[@mikerobertson6663]

No way that exhaust was that low . If it’s that cold it will freeze your hands in seconds. Spray paint the pipe black where you’re taking the reading with infrared sensor. The information you’re providing others is priceless. Thanks! I think the new white pipe you installed on the geo battery should have been even bigger. I’m estimating the flow of ten 4” pipes would need a 12” pipe to flow that much. Of course the longer the four inch pipes are the less they can flow. But end results if you had went with 12” pipe on both inlet and exhaust manifolds you would get lots more cubic feet per hour air exchange with the same fan doing less work.

[@Frenkie56]

So you say that using 12” pipe to flow those 4” pipes is more efficient? Will it also work if the outlet pipes (the vertical ones) are 6"? Meaning the air goes into 6", then 12", then several 4", then 12" and then back to 6"... I am just in designing it so I would really appreciate a good advice in this matter.

[@jimcogger9816]

What if you use smooth PVC plastic pipe and pitch it to a sump you could pump from? As a plumber I’ve run some very long sewer lines with pitch the entire length, SDR 35 PVC is thin wall sewer pipe that is easily available with fittings for many sizes.

[@SuperBatiskaf]

A very interesting idea, but more interesting the real efficiency of this approach, over the year. I think you need to install some UV lamp to clean the air goes from the soil (on exit), because this air will consist many bacterium and dampness - which is bad for the plants.

[@SuperBatiskaf]

Same idea popular in Russia, it's called "Sunny Vegetarian by Ivanov". They also installing the greenhouse on the southern slope, which allows to correct the angle of sunlight that received by plants. Because in winter, insufficient solar energy due to the acute angle of the sun's rays. But I never seen the results of this approach, only idea. Anyway, good luck for you.

[@mypearl53]

You need variable speed fans coupled to thermometers to get temp regulation

[@musicinspire1745]

The way you test the company's claim is to do a current draw reading on the motor. If the current decreases, then they are wrong, because we always restrict three phase blower and pump motors all the time to control the current draw, and prolong the lifespan of the motors. It's volume that causes the most drag on a motor, not head pressure (outflow back-pressure) with AC motors. I'm not sure why DC motors would be any different.

[@mikehankins4513]

When I was watching that video I thought the same thing.Done alot of indoor grow rooms. You could how use the fan and pull the air and save your fan life.

[@ghulamghous8861]

Will you please a complete installation video from start to end with detail. Will be thankful to u alot

[@jimmybrossard9650]

One reason to have larger diameter fan and manifold is that smaller piping will move air faster resulting in less heat exchange

[@Phenetix09]

Sir, I dont know if you'll get to see this but thank you for the inspiration. I run a nonprofit conservation organization in PA and will be breaking ground on our greenhouse next weekend. I was wondering if you might have some time to discuss ideas and let me know if my plan is sound. Thank you!

[@StIsidoresFarm]

Sorry about the delay in reply. The bottom dropped out with work off the farm. I wish I had more time at the moment, but really don't. Wish you all the best with your project!

[@CarbonConscious]

About feedback, I'd rotate that toprail to have it 'stand up' that way it will hold more weight if you are going to hang stuff from it.

[@StIsidoresFarm]

We really thought about that, but the board isn't structural - the pipes are. That and we weren't sure the fans would actually attach to that board. Originally thought we would put lights up there, but decided we wanted the fans a close to the ridge as possible. Thanks for the feedback though!

[@jayejaycurry5485]

This sure is a learning experience! I had wondered why you were using a manifold pipe so small. But I thought I'd wait to see where it went. You could have also built a manifold out of plywood like Jerome Osentowski did in "The Forest Garden Greenhouse". I'm looking forward to seeing how this project turns out.

[@StIsidoresFarm]

Yes, it has been! Despite the mistakes and added work, we've enjoyed the whole process, all of the feedback folks have shared with us - AND the fact that we now have a greenhouse! Thanks for the suggestion on The Forest Garden Greenhouse - going to look it up now.

[@aradiavenus]

Please do a video on the complete grant acquisition process.

[@LifeinFarmland]

Hey.. what is this short sleeve stuff? Great video and info. This will save someone some trouble down the road. Thank you for sharing this.

[@StIsidoresFarm]

😂 Yes, please keep the snow up your way! And definitely hoping anyone doing this system sees this video and does this correct the first time. Digging up these ends was necessary but not exactly how I wanted to spend several days of break.

[@DeepSouthHomestead]

Eric you could use one of these in your climate. LOL

[@timross3841]

The 6 inch vs 4 inch is probably a little worse than 2.25 difference. (6/4 = 1.5, and the area is proportional to the square. 1.5 squared is 2.25) With fluid dynamics, and similarly with air flow, there is friction/drag in the air flow near the walls of the pipe. Thus, the effective diameter is a little smaller. Example: a 4 inch pipe has the same cross sectional area as 16 one inch pipes, but will let far more air through quicker/less pressure. Nice videos.

[@StIsidoresFarm]

Thanks!

[@EfficientEnergyTransformations]

Never push a fluid in a narrow space, pipe is one example, always pull it. The fluid has properties to organize itself in order to decrease resistance. If you push the fluid, instead of pulling, you are creating turbulence, as the fluid in front of the one being directly pushed, creates a resistance, according to the 3 Newtons' law, there will be reactive force back, aka known as eddies or turbulence, and eddies or the turbulence will be decreasing immensely the capability of the system to efficiently channel fluid for a give amount of energy input and given fluid channel geometry.

[@colleenforrest7936]

What if you used an 8 inch pipe with a 4 inch pipe? Would that give "positive" pressure to the fan? Would that be a good thing or a bad thing for the system?

[@michaelkaylor6770]

Thumbs up by the time you said, “confession”!

[@kennynash2777]

AC Infinity inline Duct Fan very efficient

[@njabulodlamini9362]

I just saw the 35 degrees, you are kidding me !!! Whaaaaat

[@jacksvlogs9924]

114 to 35 degrees!?!?! This is incredible!!!!

[@JohnGuest45]

You need to know what airflow is involved before you can say its incredible :)

[@svgs650r]

Either the ground is still full of frost (what's the soil temp at duct depth) or the notoriously inaccurate infrared thermometer is whacked! You'll need that data for comparison

[@musicinspire1745]

The average de-rating percentage for actual airflow is about three to seven percent because of "skin effect", which describes the air friction with the inner surface of the pipe. Fluid dynamics is another term where this is calculated to get actual flow rates.

[@Rad_B_OLand]

How about a link to the fans you’re going to use. How can I find them.

[@svgs650r]

A couple observations: Hopefully you realize that your fans rated 483cfm is at 0" W.G. static pressure! As in ZERO inches of water gauge! You'll have to account for pressure drop for each foot of duct/dia. and type of duct material i.e. smooth PVC & corrugated drain. You'll have to account for pressure drop at every elbow/transition. Interesting project, looking forward to the results! Good Luck!

[@michaelp8794]

Informative vid here ... at 2:39 there is some kind of beast of an insect that lands on the truss to the left of your head. I've been trying to figure out what it was. 🤣

[@larryames8831]

Where are you located to get 35F ground temp air. Did it go down to 20-30 degrees last night and the piping was exposed to the ambient air.

[@EDUDELZO]

What entrance temperature do you have? and what temperature of exit do you have?

[@pastorgoof]

How do you calculate how much pipe is needed for the square footage like how much is needed to cool down 6000 sf?

[@MagruderSpoots]

A six inch corrugated duct is not the same as a six inch smooth duct. It has more resistance to air flow. Hope you knew that when you did your design.

[@basedbear1605]

Corrugated is much better for humidity control. The more turbulence you have, the better it will pull water out of the air, or out of the soil, depending on the season and/or humidity. And the corrugated doesn't slow the bulk of the air down that much. And, as Bob Marley said, it makes the heat exchange more efficient.

[@NwoDispatcher]

I'd say a smooth manifold would be better as the air would fill the smaller pipes harder

[@randyscrafts8575]

Where do you pour in the acid?

[@houstonsrb]

Won't you get diminishing returns as the ground around your pipes comes more in temperature equilibrium with the airflow?

[@user-tg2gm1ih9g]

you under-estimate the buoyancy of warm/hot air, it takes a lot of power to push hot air *down* into the underground tubes. Your fans will not produce the expected cfm. The tubes will also add a 'static pressure' loss, further lowering the cfm. The leaf-blower has the power needed (1 horsepower ~ 746 watts) to move the air. Your little fans ... don't.

[@agw5425]

Who convinced you that air is a adequate heat transfer media? They lied! Use a truck radiator connected to a water pipe that you lay in a s shape in the dirt, a regular fan to move the heat from the air to the radiator and a circulation pump for the water loop and you have a system that will work both for moving heat from the air and returning it when the air cools. what you get is a thermal load that will slow both heating and cooling of your green house. Good luck. Ps. the more water you have in the system the more energy can be stored.

[@markfogleman8438]

When the dewpoint of the greenhouse air is above the temperature of the battery (~April-October in your location...I'm also in the Piedmont area of NC) you will have condensation and then mold growing in the pipes. These systems may work well in the winter and year round in very dry climates but are a problem in the hot humid climate we live in. You may be able to use a HEPA level HVAC filter on the outlet to avoid breathing the contaminated air but a filter will add additional resistance and decrease the volume of air moving through the system.

[@StIsidoresFarm]

Mark Fogleman Thanks, Mark. Have you actually seen or tested for mold/spores in your system?

[@markfogleman8438]

I don't use an earth battery because of our experience with the crawlspace under our house here. We kept it open in the summer and closed through the winter for the first ~10 years we lived here. This caused a massive problem with condensation and mold and other nastiness. After a lot of remediation we now keep it sealed all the time and it is dry under there. My former career involved manufacturing heating and humidification systems for breathing gases used on mechanical ventilators in hospital ICUs and Operating rooms. I am well versed in the physics of changing water to vapor and the resulting condensation when it cools.

[@StIsidoresFarm]

Definitely something to watch out for and report back on if it becomes an issue.

[@JohnGuest45]

I`ve had mine in the ground since 2009, if its designed correctly you wont have any issues. If you go for 5 airchanges per hour you`ll be wasting your time. you need to design for a lot more than 5 ;) Your test was a little simplistic, but fwiw assuming you had 270cfm and the system is perfectly lossless, the heat transfer rate would be around 18kw per hour. Of course, as the mass heats up the differential drops and you`ll move less heat.

[@markfogleman8438]

I can guarantee that I'm not confused about how dewpoint works and that I'm not an ME. I can also guarantee you would not want to spend much time breathing the air coming out of those pipes unfiltered as they will be pumping millions of mold spores and other potentially harmful microbes (remember Legionella?) into the air every hour after the first summer of operation. Warm moist air coming into contact with cool plastic drainage pipe buried underground will loose energy and not be able to maintain molecular humidity. The pipes will condense and collect water. This in turn creates an environment favorable to grow mold, mildew and other nastiness in the pipes. Blowing air through these moldy pipes will spread mold spores into the air inside the greenhouse. In our part of the world we have average dewpoints in the 60-70 degree range from April to October with spikes into the high 70s during tropical storms and hurricanes. Mold needs >60% RH to thrive. The RH in his pipes will be near 100% for most of the year assuming the ground temp around the pipes is around 50 degrees. A better option would be to run a network of coolant filled piping underground and circulate this fluid through heat exchangers in the greenhouse. Fluids are much better at transferring energy than air.

[@waynegabler6570]

7:40 If the 4" fans were used, the heating cooling cycle would not be 'flat'. Does it need to be flat during the day if the temp can be allowed to rise during the day. The heating effect of the night would be enough that the 24 hr cycle is 'balanced' (say 8am and 8pm the temps are equal) Smaller capacity fans running 24/7/365 would be more economical while allowing the greenhouse to function all year. Would there be any difference if the intake was at ground level and after being pushed through the underground pipes the exhaust was at the peak of the greenhouse where the cooler air was mixed with the warmer air before it descended to the lower levels of the greenhouse. That would keep the warmest air for the plants, and the colder air from the ground might be cool enough the growth of the plants is stunted.

[@bolapromatoqueejogodecampe8718]

St Isidore, pray for us!

[@MichaelVandeburg]

Look up the old man's system who has been growing citrus in thermal greenhouses. Got a bunch of videos on KZbin. You should be running individual tubes a 100 feet long and 8 feet deep to convert the air to earth's temperature at around 58 degrees. I would be shocked if this worked. I will watch more of your videos to see end result.

[@resolutekravmaga651]

How did you do the calculations? Did you find an online calculator or did you do it all handrolically yourself?

[@cecfarns6788]

Question... For heating purposes, wouldn't it be better to pull air from the floor and push it out a higher vent pointing down? And vice versa for cooling..

[@JoeAroner-SIWAYTV]

I thought about this too. With the venting lower you get a mixing of air. In Southern California all air vents are in the ceiling for cooling purposes, but in Oregon all the vents are on the floor for heating in homes.

[@ericwilson8848]

What was that website? For ecosystem design

[@Nadine----]

Angels watching out are everywhere.

[@iguanapete3809]

I'm impressed. but where do you live that it's 114F at Easter time?

[@TheOleHermit]

T's on the 6" manifold would have made better adapter/connections with the 4" corrugated runs. IMO, if the side walls of the greenhouse were plastic and the roof screen, that would form a chimney effect. The cool air in the tubes would be drawn into the greenhouse by convection currents created by the inside hot air rising and exhausting out the roof. IOW, the lower part of the greenhouse would be filled with the coolest air, drawn out of the ground (if your objective is to cool the greenhouse, as in AZ). No fans required. 😎

[@jake.presents]

He's in North Carolina. They're cooling in the summer, and warming in the winter. He said the air needs to be turned over ~5x/hour. I don't think a zero-fan system has that capability (especially since there are no top nor bottom vents)

[@jamesfrazier366]

Perhaps a more cost effective way to get some heat to the green house is a propane heater that actually produces CO2 as a combustion by product. Needless to say this has it's problems, but it will boost the CO2 levels in the winter when air circulation is a problem.

[@CHARLESBW453]

After it's all been said and done and the heat is getting higher in the greenhouse what's the final evaluation of temperature going in and temperature coming out of the pipe getting ready to set up my own system like to see what your evaluation was

[@StIsidoresFarm]

The real test for this system will come in the fall and winter. What we can say right now is that it is too small to offset the tremendous thermal gain from the summer sun. Even with fans, we had to add shade cloth to reduce heat inside. That said, the air coming out of the pipes is consistently 30-40 degrees (or more) cooler. So we could see where a much larger system, one that could really exchange the volume of air quickly could work to keep it cool during the summer. The one cold night we had before spring really set in was a low of 34. The system kept the temps around 60 the entire night. So if I had to do it all over again, and could afford it, I would put in larger intake and return pipes as well as fans.

[@chinbatbattumur2622]

Hello, Can this geothermal heating technique be used in cold temperatures reaching -40C at night? Thanks

[@fezwhy]

Yes it can. However it will require some more engineering to keep things above freezing.

[@ozarkdaredevils]

Did you glue the joints under ground ? They will leak , your ditch becomes a channel for water .

[@sli-fox]

I found these videos interesting. I’d spend more on a DIY solar water heating method. Water can transfer heat much faster and you could store water for use at night.

[@JohnGuest45]

water isnt the best option for this application for a number of reasons...

[@TheRainHarvester]

@@JohnGuest45 What about closed loop glycol with a heat exchange?

[@sittingindetroit9204]

Is this saying your ground is below 35 degrees???

[@TimClymer]

Threefold Farm here again. Good progress and glad to hear you made the switch to a larger manifold! Will you be monitoring the greenhouse temps once it's up? I've found it to be very helpful to monitor inlet and outlet temps as well as the temperature of the soil. In terms of cooling, I haven't seen enough cooling with our system such that we'd be able to avoid either opening the sides or door even on cool sunny spring days. The solar gain just seems to be too much. Your system may be setup better than ours. We currently use 3x 5,000CFM HAF fans to push air, but I think the static pressure causes them to behave more like 3,000CFM fans. Even with that, we're moving air about 15x/hour and aren't able to actively cool the structure. I recently started a private group for commercial "climate battery" growers on Facebook that includes a few other farms in order to share experience of what works and doesn't. I'd value your input on there if you'd like to join. Let me know and I'd be glad to add you.

[@StIsidoresFarm]

Tim, we'll definitely be monitoring things once it is up and throughout the year. You're running some huge fans! We would be very interested in the FB group, as we have hope of building a much larger greenhouse and want to learn more and improve the system before we do it.

[@TimClymer]

Glad to hear about monitoring! We use Acurite products to monitor ours as they're inexpensive and (relatively) reliable, plus we can view temps through our phones. We'd love to have you part of the group. I tried typing in the name of your farm to add you but couldn't find you. Perhaps you could request to join it and we'll add you that way. The group URL is facebook.com/groups/1594790417277905/ I'm currently restricting it to commercial growers as I'm really interested in the performance of larger-scale systems.

[@rebeccakimmet5474]

Disappointing to hear that the cooling is not as effective as hoped. I believe the 5:1 ratio rule of thumb is made up out of hot air. obviously that ratio is going to be a range, and vary dramatically with floor area vs volume, solar insolation, climate, time of year, N/S vs EW orientation etc. So you can have an 8,000 pound car with a 20 HP engine, it won't be quicker off the line than a Tesla, but it might be perfectly appropriate and functional. What you don't want is a 200 HP engine with tires, axle, transmission or clutch designed for 20 HP, OR a 20 HP engine with those designed for 200 HP, right? A simpler way to measure airflow is to use the pump curve that's published for any reputable fan. Even better if you have the watts overlaid on the pump curve. A simple "Kil o watt" meter will give you the watts, and you can compare that to the pressure with a slightly more expensive Dwyer magnehelic gauge in the appropriate range to double check your CFM, good enough for me anyway. Builditsolar is a great site for anyone doing home engineered solar anything, and home engineering is MUCH BETTER than NO ENGINEERING which, unfortunately applies to most of what's on the tube.

[@JohnGuest45]

you should aim to put the entire greenhouse air volume underground 25-40 times per hour for effective cooling, i designed mine to handle 60 so i could experiment with the flowrate. Fit multiple sensors inside the tube to track the temperature as the air travels through, vary the flowrate and collect real data so you can base your conclusions on what is happening rather than what you imagine is happening ;). Trust me, you need a lot more fan power than you imagine to outrun the cooling capacity of a well designed installation.

[@TimClymer]

John, I appreciate the info. How are your numbers calculated? I've heard anywhere from 10x/hr to 60x/hr for cooling. To get a volume like that I'd need to at least double if not triple my fans (and probably also my tubing). Do you have a working version of your house? Would love to see it and learn more about it.

[@JoeAroner-SIWAYTV]

I think someone accidentally hit the F to C button on the thermometer. Underneath the frost layer depending on where you are located, soil tends to be 55F. There is a reason wine storage is recommended at 55F. 🤷🏻‍♂️

[@sofusdjacobsen]

Ok first i am from Denmark so my English will not be perfect But every time you make a 90 degree bend on your piping you will lose a lot of air flow And pushing is harder so maybe put your fan to the outlet

[@friendlyneighborhoodmechan2606]

Nice info thanks About How wide and how long and height is the greenhouse that you built?

[@StIsidoresFarm]

Don't remember the dimensions offhand. They're posted in the first video of this series. God bless!

[@timb7814]

I think a modern, high efficiency air source heat pump would be much more effective at heating/cooling and ventilation, and also cost less than you will have spent on this entire ventilation system.

[@persistentone3448]

If you look at the Eco Systems Design implementation of this idea, they are bringing the four-inch pipes into a 16 inch manifold tube, not a 6 inch manifold. In effect, they are able to run 16 4 inch pipes (approximate) into the 16 inch manifold while allowing full saturation of the four-inch pipes. Some quick math behind that. A 4-inch pipe has a 2-dimensional area of 12.57 square inches. A 16 inch manifold pipe has 201.06 square inches. 201.6/12.57 = 16. Your design has six 4 inch pipes? If yes, then you would need a 10 inch manifold to completely saturate the six 4 inch pipes. Area of 10 inch manifold cross-section is 78.54 square inches. 78.54 / 12.57 ~= 6.3 of the 4 inch distribution tubes.

[@JohnGuest45]

If the 4" tubes protrude into the 16" manifold you will incur some major losses, the transition should be as aerodynamic as possible but with tubes its not always easy to do. The 10" pipe may not be big enough depending on the length. Eco systems recommend tube lengths upto 35ft wgich limits the amount of air to around 50cfm. Assuming the system has 16x 4" tubes and they all get an even share, the manifold should be designed to handle at least 800cfm with as little loss as possible. If, for example, the manifold is 20ft long you`d be better to go for a 12" manifold not a 10". Fwiw, Eco system designs are based on John Cruickshank`s original design work. Its also clear from this page that they respect and appreciate John`s great work in this field www.ecosystems-design.com/blog Its unfortunate they werent involved in the discussions on John`s "plain to sea" forurm circa 2008-2010 when collaborative testing and data collection culminated in some radical changes to the original design criteria, Some folks who had systems in the ground actually dug them back up so they could benefit from the new information. Its good that Eco systems have adopted one of the changes, which is to recommend much higher air turnover rates but seem totally unaware of the other sweeping changes. Johns website wasnt updated with the new information as he passed away in 2011. . .

[@organiccleanfoodconnection]

Your pipes are set at 5 feet? How do you decide how deep? The geothermal underground greenhouse are set at 8 feet. I’m in North Kansas. They make 4 inch bilge air pumps 270 CFM would that work?

[@brianmifsud4531]

You should look into squirrel cage blower. They will move air through 4 inch pipes no problem you'll get the cubic feet per minute you need at the higher pressure. Pancake or coaxial fans are only for low back pressure systems that doesn't apply here. It's all based on horsepower 1 hp will move about 2000 ft.³ per minute this is the size of most blowers in peoples furnaces in their homes

[@StIsidoresFarm]

Could you share a link to a fan that would work for this? Perhaps we just didn't look hard enough, but didn't see them. Thanks!

[@brianmifsud4531]

Here are the type of fans you should consider. Generically, they are called blowers, but are nicknamed "squirrel cage" because they look like a rodents merry go round. electricmotorwarehouse.com/squirrel-cage-blowers-1/ Picking the right one is kind of tricky. Any system of ducts will behave uniquely. There's friction inside the pipes which is a combination of their diameter, the texture on the surface (smooth or corrugated), how long the pipes are (more length is more friction), and how sharp the turns are, (smooth gradual bends are always better than hard 90's). This all adds up to resistance to airflow. If you could somehow measure the amount of air you were pushing through the pipes per minute, you could also measure how much "backpressure" or resistance the fan was fighting to achieve that flow rate. Fans and blowers are designed to have a happy zone where they run efficiently and don't overheat. If they are too powerful for the set of pipes and the system resistance it presents, they just make a lot of noise, and use too much power. If they are undersized, the can't overcome the backpressure or system resistance. The airflow through the fan will be inadequate, and it will burn up shortly and not pump much air. The trick again, is to understand the relationship between flow rate and resistance in your piping system.

[@mottthehoople693]

@@brianmifsud4531 axial V centrifugal fans...

[@MrBiggameslayer]

My brother works for HVAC company. They tear out old furnaces all the time and he gives me working 2 ton and 3 ton blowers (squirrel cages) all the time to move air in my barn. Move a ton of air. Because of the dust and debris I burn them up... but in a closed system like this, they should work great. Even an older used one.

[@danpitsch6328]

Did you consider friction loss on corogated vs smooth wall pipes?

[@JohnGuest45]

@@NotAsTraceable You would be amazed how fast the air drops to ground temperature in the tube. The thing to remember is its not how long the air spends inside the tube, its how long the entire greenhouse air volume spends in the tubes.

[@chuckeynewkirk199]

What kind of Grant did he get if I may ask I'm interested in doing the same thing I was hoping to build a greenhouse that is 40 feet wide and 100 ft long Underground on a cliff