Having enjoyed our 24' x 24' Aquaponics gh for 10 years now I have to say this is by far the best description and advice I have seen on YT. You make me want to build a second one myself especially since we now have our own excavator. Great job👍😎👌 BTW if your fan has ball bearings you can just replace them about every 10 years for chump change.
I have been following you for a few years. Good job on your second greenhouse! It seems that geothermal greenhouses and earthship greenhouses are the best. And I am seriously considering a buried pipe system for my home to heat and cool.
Its little weard at 37:59 there is image that the fan are just connected to 10 pipes that just go down and under and are never connected to the pipe that goes upp again. and at 38:07 they are connected to the pipes from fan and up ? What is right?
Thanks for sharing the video. I notice a lot of people on UA-cam calling this style of greenhouse construction 'geothermal.' That is a misnomer. This is not geothermal. This is simply a geo-exchange system.
Exactly. Technically, the heating capacity of this system is limited to the solar energy that enters the greenhouse. They use the ground underneath it as a thermal mass, or a thermal battery.
From what I have read all over the net from people who have done these type of projects, running a single run of pipe would be MUCH less efficient than the way he ran it as several individual runs of pipe. The reason for this is that the air would "bottleneck" with a single run and you would NEVER get the turn over in air that you need to get the results you got. I LOVE his system and it's quite impressive how efficient it is. I suspect that a faster running fan when the greenhouse starts to warm up warmer than the air exiting the pipes would "charge" the ground with heat more efficiently for nightime discharge. This is also an advantage with the multi-pipe run set up. You could never get the type airflow in the system you needed with a single run in order to remove excessive ambient heat.
Engineer here. This is not rocket science; it has many variables, so one doesn't need to overthink it. But, there are several reasons why this is better than a single run of pipe. As for the air temperature and flow rate, here are some basics. To remove heat from the rock, the air needs to be cooler than the rock. As the air heats up in the pipes, the air will become closer to the temperature of the rocks, so it will not pull out as much energy. So, while faster air seems cooler, it will actually be removing more heat from the ground. Similarly, to heat the rocks, the air must be hotter than the rocks. The hotter the air, the faster the ground will store energy. Blowing the air through faster to the point that it doesn't feel much cooler after heating the ground is ideal, despite seeming counter-intuitive. But, as I said, the details of it don't matter. It will work well enough either way. As he said in the video, you don't want to burn your fans out. The biggest issue is that, if the air leaving the pipes is too close to the rock temperature, a certain length of rock may not be being used to heat or cool the air, basically being wasted. It would be like never charging your phone battery over 60% or something. But, that doesn't seem to be the case here
I am not allowed to have a structure this size because of the HOA guidelines but I wanted to watch your video and see how you built your greenhouse and pass it along to my brother Jack who is going to build one on his land. Thank you for sharing your knowledge and experience with us sir. I would need a smaller version so it cannot be seen by my neighbors. God’s blessings to you and your family 👍
@@JohnGuest45 TY,,, wish I knew more about your comment ! I only want to do this one time,,,,, any help would be appreciated 👍 kinda new to the green house building,,,,,,,,,
@@bustersmith5569 Hi Buster, If you examine the design in the video you should be able to spot quite a few things that will limit the airflow. For example, having 10 tubes protruding into the bottom of a barrel is not going to provide a smooth transition for the air.The air from the fan may enter some of the tubes but most of it will impact on the floor of the barrel and travel back up where it meets the air coming down.. If the tube ends were flush with the floor of the barrel and radiused, the fan would deliver a lot more air. The system fan has a free flow of 863cfm according to the spec. If the greenhouse volume is 8000 cubic feet, you would have a turnover rate of just 6.47x per hour. For effective cooling you should design the system for a turnover rate of at least 20x an hour. In the spring when the mass is at its coolest, you can run a turnover rate of 45x an hour before the air exiting the tubes rises above the ground temperature. If the air temperature exiting the tube is the same as the ground temperature, you can be sure the full length of the tube is not being used to transfer heat. Its important to note that for best energy efficiency you should run the fan at a speed that keeps pace with the incoming gains. Its better to run at slower speed constantly than flat out intermittantly. Higher flowrates are required in late autumn when the mass is warmer which results in a smaller temperature differential and therefore less heat transfer. The thing to remember with these systems is it isnt how long the air spends in the tubes, its how long the entire greenhouse air volume spends in the tubes. Most systems use excessively long tubes which limits the amount of air you can run. I guess it comes from the notion that long tubes and low flowrates are the only way to provide sufficient dwell time for the air to heat up in the tubes. I use short tubes in a unique arrangement which provides efficient heating and cooling. I designed the system to handle a turnover rate of upto 60x an hour. Most of the installations that were around at that time were using the recommended 5x and didnt have sufficient fan power to test higher turnover rates. The turnover recommendation has more recently been increased to 12x which is better than 5x but still low for effective cooling performance. The bulk of the heat stored in the mass comes from cooling, not the earths core as some would have you believe.
Great Vid Thank you for all your time ,i am in upstate NY lake geourge region zone 5 A, can you please shed your thoughts on if radon with this type of pipe system has any Radon issues to the inside air quality?Thanks Rich and God Bless
40:00 I don’t understand why he said you want to pull air into the intake from higher ( hotter ) if using rock, but to pull cooler air from lower if using dirt. It would seem like either way you’d want to pull the hottest air. What an I missing ?
if you would have ran the tubes under ground to a header instead of capping off the bottom row would it have been better for pumping the air into the green house or do you think it is better to heat the ground. Looking to build a greenhouse this spring just trying to get the best possible construction so i don't have to do it twice lol.
43:10 setting the fan speed by measuring warmest air is not necessarily optimal, due to heat not being the same as temperature. It may be confusing to some. (If you visualize a solar collector heating a pool, you might understand that the hottest water flow means less water which might also mean less heat). What is the reason for the different pipe intake level for soil vs rock?
I plan to do dirt geothermal with perforated corrugated tubing. Should I be concerned about dirt, or bugs getting in the tubing underground? What would keep the dirt from getting in?
Really like geothermal greenhouse just not sure it is something worth spending the money on for one in Central Texas. We don't get many freezing nights but the brutal summers tear up the plants. Really like you deer netting idea, definitely will do that. Glad to see your back posting videos sir.
You can also use it for cooling that's what I'm doing on mine I'm up at four thousand foot 13 miles from the desert and I'm going to be 80 to 90 degrees all summer and I have a glass ceiling on mine so I'm going to need to cool mine more than eat it but it's also going to work for heating during the winter which is highly beneficial
The geothermal brings in air from the outside and then runs it through and then yes I have ventilation Vents and holes up high where that will let the hot air out bring in fresh air in cooling it and so it getting fresh air and it's also circulating fresh air and pushing the hot air out it works okay I mean the room is working great but the cooling aspect of it is not as good as I hoped but it was worth a try I'm probably going to put an AC in there for next summer
We have a USDA cost shared high tunnel and we’re told we were not allowed to have a climate battery and we had to grow in the ground and not in containers.
Have you noticed a difference in the amount of air coming out of each tube and the temperature? Just wondering if more air is blowing thru certain tubes as they are shorter or a more direct route for the air (less air resistance)
You must also know that according to experiences done by a university, to maximise the heat exchange in the soil the air must stay between 3 and 5 secs in the pipes. Less than 3 secs the heat exchange will not be completed and more than 5 secs will mean that your pipes are unnecessary too long. That is why some basic calculation are mandatory to get the most efficient system.
39min in, what is your reasoning why you wouldnt want to pull the hot air from the top of the greenhouse into the SOIL version? Also, do you have an anemometer to measure the CFM coming out of the pipes?
There shouldn`t be a lot of difference in the air temperature. if there is the sytem isnt moving enough air. I find it amazing that folks spend thousands on the installation but have no idea what its doing. Meters are cheap these days, typically less than a hundred. ua-cam.com/video/u9VYHcL5cdQ/v-deo.html
@@JohnGuest45 totally agree.. if there is that large differential...you need to add a circulation fan. I have meters for days haha. All about that data.
I am confused as to why your pipes are not all connected? Seems like it would be more efficient to have your intake be a continuous loop to your outtake giving max time for the air to be heated? Perhaps I am mistaken but in the model it looks like the input pipe are simply capped after running the length of the greenhouse?
Anthony Webb This one is more like an open circulatory system, similar to an insect, rather than a close circulatory system similar to a mammal. It floods the open space between the rocks to heat the whole bank of things. It’s not intended so much as to have good air flow as it is to have good thermal heat transfer. Hope that helps.
The ends are capped, forcing the air to exit via of the perforations will severely reduce the amount of air you can move through the tube per unit of time. If you limit total airflow, you also limit how much heat you can move into the mass per unit of time. The air wont flow evenly through the rockbed, it will take the path of least resistance.
I am about to lay the black 4" perforated pipe, but am very concerned that the rocks will crush it. What pipe specifically should I use. Is all 4" perforated pipe basically the same? Or not?
Crushing isnt normally a problem, when correctly installed you can drive heavy machinery over it. Perforated pipe is the same in terms of its purpose which is to allow water in and convey it to another location. It isnt designed to let water out, easy to confirm by checking where the perforations are located. If you pour some water into the pipe you`ll see that water gets trapped at the bottom of every single corrugation with no way to drain out. It will have a negative impact on the heating and cooling performance.
So basically you are making the geothermal greenhouse for the purpose of warming the greenhouse to the temperature of the soil. I need to know in the summer to cool the warehouse what do you need to do and if the solution is similar what would the temperature difference be between outside temp and inside temp.Thanks
Thank you for the links, I will visit the green house supplier, and I can use the fan speed controller for the exhaust from the wood stove that is channeled through a mass heater that I built in my green house. I like the idea of a geothermal system that maybe affordable for me, with the usda cost share program.
Do you know or think that there is a benefit to going deeper than 4 feet? I am considering doing a aquaponics system by digging a 10 to 12 foot basement with the fish in the basement and the plants at 2 to 4 feet below grade. I would put the geothermal system at 14 to 16 feet?
A correctly designed system will heat and cool. Its important to remember that a system that is not great at cooling the greenhouse is also not great at transferring heat to the mass
Great information on geothermal design. I plan to install soil geothermal this year. Could 4" corrugated pipe be bend on 10" radius (20" between trenches)? Could the S-shaped trench be made with Gasoline Drill and Trencher? I like that you give us the recommendations with experience as some people tell unreasonable theory (5x to 20x greenhouse air exchange), your experience prooved my thinking on minimal required circulation, (with too high airflow condensation in pipes goes away and the efficiency drops) and I like a quiet greenhouse. Thanks
i would recommend keeping the tubing as straight as possible with no tight bends as it will impact on the amount of air you can run through it. Serpentine layouts should be avoided at all costs.
Another idea on the inflation fan is to put a geothermal tube in tha ground and pull from that. The ground should dehumidify the air as well as warm it up so as to help with temperature modification and stability. Or so I think and understand. Ty.
Did you keep a record over this past winter (November 2020 thru February 2021) of the outside vs. inside temperature? Also how cool did the greenhouse actually get down to at night this past winter? Thanks
Thank you for this very-useful information! It is much appreciated. I didn't see a dehumidifier in this greenhouse. I'm guessing you don't need one because the condensate should leak out of the tubes and through the rock which should cause it to dissipate into the soil. Is that correct? If so, I'm wondering if I use the soil method with rock under the tubes maybe I wouldn't need a dehumidifier. What do you think? I'm not sure how much rock would be needed. 2"? 4"? Would it be the same amount as is used for a french drain?
I need to put a dehumidifier in this greenhouse. Something I haven't done yet. I'd put 4 feet deep of rock the entire foot print of your greenhouse to have enough heat sink to hold the heat over night.
Great and informative as always. I was just about to pull the trigger on the greenhouse described in the mittleider book that Jim Kennard has in Idaho. Wondered if you had any thoughts if it was a good design? Or if I am better off with the kit you describe in this video. Thanks.
Hallo Sir, from Ukraine, Kiev. I've watched your video till the very end, thanks for this detailed video. Just wander if You may know, should I put isolation under the pipes IF, I am going to put my greenhouse 2 meters underground and the underwater is about 2,5 meters below ground level. So, my plan is put water isolation, heat isolation, pipes on some gravel and cover it with sand, to serve as thermal system, put the isolation material (foamed sheets), make a waterheated floor on the top. Would be pleased to hear from you. Cheers Roman
Great video. Question, I am thinking about building a similar setup but it's close to a river so there's a high water table and I don't think perforated pipe would work because it'd just fill with water. Do you think a system would work with 4" solid pipe in place of perforated to keep the water out?
A high water table will tend to take the stored heat away from the system. Raised beds can be used to increase the effective depth. They also reduce excavation costs.
Great video I heard your name come up from another video watch watch two out three or four different subscribed channels on geothermal and I went ahead and did it kind of wish I would have watched some more but I had enough information to build my own and seems to be working still got to finish it and test it but I appreciate the knowledge and nice video thank you
I am in the northeast and certain regions have natural radon gas in the soil. I imagine perforated pipe would pump this radioactive gas into your greenhouse. Has anyone commented about your design and whether this could be problematic?
This video and the one before this one about your greenhouse are very helpful. Lot's of great information. I am getting ready to build my geothermal greenhouse this fall and this info is super helpful and very much appreciated.
His design doesnt allow sufficient airflow for effective cooling. The real kicker is that its the cooling that provides the lions share of the heat stored in the mass. A system that doesnt cool, doesnt store as much heat either.
@@JohnGuest45 Thanks JohnGuest45! I always wondered why the "battery" did not work in reverse. Like having a row of water barrels for table support should keep the greenhouse warm during winter and cool during the summer.
@@newgardener A well designed system will provide effective cooling. Water barrels start losing heat as soon as the greenhouse air temperature drops, not at 2am when you need it most :)
I know you are really proud of this design and all, but physics says you are running the system backwards. In order for air to release the heat energy efficiently, you need to have a drop in pressure. You need to put the earth battery under a slight vacuum. You always want to be pulling air from the coldest part of the system, not trying to push hot fluffy less dense air down. By pulling the air on the cold side where it is dense, you will be pulling twice as much air from the top of the greenhouse. And storing twice as much energy in the process. Pressure = Heat. But suction = cooling and heat storage.
You dont want to use perforated pipe for geothermal applications In most designs.. this guys just so happens to call for it. Also a smooth surface interior pipe is a bit better for air movement so it will save you power and ware and tare on your fan.
His particular design here, with the rock fill, appears to actually *require* that the air leave the tubes through the drain holes, filter through the rock exchanging heat, and then re-enter the second set of tubes, and then return to the greenhouse. So in this particular specific case no, it requires those perforations to work at all. However if you're using the more 'normal' kind of system that has a continuous set of pipes from entry to exit, the in theory yes. But the problem is that you can potentially get condensation in the pipes. With no pipe perforations to let condensate out, you're creating thousands of tiny troughs for water to collect, and mold to form, which is not good.
i like the green houses. i am also going to be a resident of SE Idaho again in two weeks after being gone for 30 years. i will be living 25 miles east of IF. could you e mail me, i have some questions about the how to of the green houses. i have checked on some designs in western nebraska and would like to compare it to yours before i build. thank you
I believe he lets the air leave the upper tubes through the small drainage holes, and then the air goes through the rock bed, in the space between the stones, enters the lower pipes through those drain holes, and then out those pipes. It makes direct air contact with the stone, which probably makes for better heat transfer. It also probably hugely increases the friction losses. The 10" intake tube has a cross-section of 78.5 square inches. One 4" diameter tube has 12.56 inches of cross-section area, and ten of those is a total of 125 square inches. So the intake tube is under-serving the laterals based on raw area. But given the amount of friction losses he's likely working with, he probably needs that 60% extra lateral area to compensate.
@@mattmanning1572 You are correct, massive losses with no guarantee the entire mass is being utilised. If the system was completely lossless, (which it isnt) the fan isnt capable of moving enough air for a greenhouse that size. Its hard to believe someone would spend thousands of dollars on an installion without running the numbers first.
@@JohnGuest45 Also, his measurement was temperature to determine the fan speed. But heat (btu) should be measured to determine the best flow rate for heat transfer (not temp).
@@TheRainHarvester That is correct but in ths case it doesnt apply because his tubing arrangement.wont support that kind of flowrate. The other thing to consider is many installations use basic thermostats to control the fan which dont take account of the mass temperature. This can lead to a situation where valuable heat that could have been stored is not stored and another situation where the thermostat calls for heat and runs the fan even when the mass has no useful heat to give :) When the penny finally drops and folks start to design systems that work, i wont have to keep trying to save folks from making an expensive mistake by following the advice in vids like this one.
Just got the first layer of poly on mine this week... I'm concerned about the lock wire channel not being large enough to handle 4 layers of poly on the ends. How did you do this? Deeper channel?
Regarding your method for determining the optimal speed of the fan: It isn’t just the outlet temperature of the air that matters, the volume of air exchanged is also important. Consider this thought experiment. Case 1: the air exiting the tube is hot but the air exchange flow rate is low. Case 2: the air exiting the tube is not as hot but the air exchange rate is higher. Case 2 may actually warm the greenhouse air more than case 1 as a greater volume of heated air and thus a greater heat flux transfer occurs under case 2! Assuming that your greenhouse air is well mixed, a better location to measure the temperature of the air is at the drum at the end of the greenhouse at the OPPOSITE end to where the warm air enters the greenhouse from the buried tubes. A thermometer placed at that location would better account for the total amount of heat being conveyed to the greenhouse and allow you to fine adjust the flow rate on the blower to its optimal speed. Hope that helps.
In practice, the optimum fan speed is one that maintains the desired greenhouse temperature :) In terms of maximum heat exchange you should aim to maintain a temperature differential over the full length of the tube. Most installations are unable to achieve this due to poor design. Most dont have temperature sensors to measure the mass temperature, which, when you consider the cost of an installation, beggars belief. A low flow rate will result in the air cooling to ground temperature in the first 10ft of tube and then coasting the rest of the tube without any further change in temperature. Ccalculating the heat transfer rate is relatively easy if you know the inlet temperature/RH%, the outlet temperature / RH% and the flow rate in CFM. Its important to understand that RH% plays a major role when it comes to heat transfer.
He appears to be having the air leave one pipe through the drain holes, and filter through the spaces between the stone, and then enter the other pipe, then back into the greenhouse. So he's probably trying to get more contact with the heat storage media, this way. It probably increases the friction losses tremendously, but it may be a good way to overcome the slow-ish thermal transfer properties of the pipe. The stone probably transfers heat at least 3x as fast as the pipe itself.
@@mattmanning1572 He`s getting less contact with the mass because the air can/will choose the shortest path. You also need to consider the rock may only account for maybe 60% of the storage volume due to gaps, so 40% of the "thermal mass" is air. You want the air to connect with as much of the mass as possible, you also need to reduce the frictional losses to get the most from your fan or you are wasting power and $$. The contact time in respect of how long the air spends in the tube isnt important, its the amount of time the "entire" greenhouse air volume spends underground. If you send a cupful of the greenhouse air through the tubing once a minute it may be warm but its still only a cupful per minute which wont make an ounce of difference to the greenhouse air temperature.. If you could put the entire greenhouse air volume underground once a minute, that would increase the greenhouse air temperature. The designs in the video reduce airflow, pretty much the exact opposite of what you want.. The serpentine layout he recommends is a complete debacle, ua-cam.com/video/T-fa_5co2FM/v-deo.html The losses on a 300-400ft length of heavily corrugated tube with 9x 180 degree and 2x 90 degree bends will be immense.
I prefer to draw air out of the ground rather than to blow it in. So my blower is on the exit side. Here’s why? Instead of air entering through plastic drainpipe risers, I have a manifolded flat-black passive solar collector made out of metal downspouts against the north wall of the sunken greenhouse that heats the air before it is drawn into the ground. I also have a vent on the manifold of the collector that allows the rising heat inside the collector to exit directly into the greenhouse (and bypass the ground loop). This allows the greenhouse to be heated up quickly if needed. At night, there is no heat being added by the collector, so cold air from the floor of the greenhouse is drawn in through the ground level intakes of the collector. Thus excess daytime heat is stored in the thermal ground battery and is retrieved at night when it is needed. Another advantage to blowing air out, rather than blowing air in is that, if you live in an arid climate, you can attach a DIY evaporative cooler to the blower and cool the air in the greenhouse quickly to prevent heat stress and wilting or blow it across dry ice to add some CO2 to make the plants grow faster. Yet another advantage is that blowing humid air into the ground causes condensation and the moisture fosters the growth and proliferation of mold. Sucking air out dries the soil preventing this condition from happening. Though I haven’t tried this, you could also use the blower to generate electricity or even to spread powder or add air to a compost heap or to a bubbler, or to supercharger a rocket stove, etc. (as long as this will not burn up the motor on the blower). If you live in a cold climate, to add additional heat, I recommend making a ground battery out of a couple of thermal solar panels, two loops of pex pipe (and for added safety, I’d use heat tolerant pex for the loop connected to the panel), a water pump, a junkyard truck radiator with a fan (or create a pex pipe radiant floor attached to the bottoms of pallet walkways), and a glycol water mixture for the fluid. The high heat capacity of water makes it a much more effective fluid than air for transferring heat to the thermal battery. Store it up all Summer and then draw it out all Winter.
blowing humid air into the ground causes condensation and the moisture fosters the growth and proliferation of mold. Sucking air out dries the soil preventing this condition from happening. You are mistaken. I`ve had my tubes in the ground for 13 years, mold is not an issue. Air takes the path of least resistance. Blowing air creates a positive pressure, any leaks will be seen as high resistance paths compared to the tube exit. Sucking air creates negative pressure, any paths near the fan will be used to pull air in, this includes permeable soil. The idea that the soil will dry if air moves in a certain direction is just plain silly. If the air is warm and moist and the tube is cool, the air will drop to dew point forcing water vapour (a gas) to change phase (to a liquid) and condense out inside the tube regardless of whether the air is being sucked or blown. If the inlet air is cool with a low RH% and the ground is warm and moist, the RH% of the air will increase inside the tube, also regardless of whether its being sucked or blown. The limitation of any system is how much air you can run through it.
@@JohnGuest45 Where I live the ground temperature below the frost line is approximately 50 F. Summers are hot and humid (90 F and near 90% humidity). Pumping hot humid air into the ground will definitely cause condensation and if not drained out, the accumulation and pooling of water and ultimately mold growth.
@@JohnGuest45 True the direction of air flow does not cause drying- I never said that it did! Soil does however dry if you blow low humidity air across it and condensation does occur if you blow warm moist air across a cool surface. That’s not silly, it’s physics!
@@resilientfarmsanddesignstu1702 You will not prevent condensate forming in the tubes because a greenhouse full of transpiring plants isnt conducive to a low humidity environment. If you measure the temperature and RH% of the inlet and outlet air along with the CFM, you can calculate how much condensate is forming in the tubes. If you calculate the difference the outlet air makes to the entire greenhouse air volume in terms of lowering its RH% you will find its not a significant amount. The main factor is the amount of airflow you have available and, in most cases, the system design is the limiting factor.
We are in the Rexburg area and wondered if we could come and see your set up and ask questions in person? I also sent you a message on your facebook account. Thanks
one thought, you said the cost of stone over just dirt for thermal storage was not worth the cost. One could dig out as you did, and instead of dirt or stone drop in 44 IBC totes full of water and deck over them. Water has more BTU storage capacity than either of the other mediums. You could use either a conventional solar collector, or a row of IBC totes above ground on the south side painted black, and a circulatory pump and link the above ground ones to the in ground ones to charge them with heat during the day with the pump running, and have the pump off at night heating with just the radiant heat. check this page out for the heat capacity of water per gallon. www.engineeringtoolbox.com/energy-storage-water-d_1463.html Great video, and awesome green house! ETA, I dont know what latitude you live at but 120F in february is incredible! Idaho......now I am really impressed with the efficacy of your setup!
From a plants perspective, the IBC`s wont provide any of the benefits you get from usingh soil as thermal mass. There is much more to it than just storing heat.
I was surprised how low in temperature lemons will grow. This is do-able. Thank you Mr LDSPrepper.
Having enjoyed our 24' x 24' Aquaponics gh for 10 years now I have to say this is by far the best description and advice I have seen on YT. You make me want to build a second one myself especially since we now have our own excavator. Great job👍😎👌 BTW if your fan has ball bearings you can just replace them about every 10 years for chump change.
Thank you thank you! So glad you're back on UA-cam!
I have been following you for a few years. Good job on your second greenhouse! It seems that geothermal greenhouses and earthship greenhouses are the best. And I am seriously considering a buried pipe system for my home to heat and cool.
Totally awesome. Thank you! Keep up the good work.
Thanks for sharing with us, David. Great job!
Great build, I'm very impressed.
Its little weard at 37:59 there is image that the fan are just connected to 10 pipes that just go down and under and are never connected to the pipe that goes upp again. and at 38:07 they are connected to the pipes from fan and up ? What is right?
Thanks for sharing the video. I notice a lot of people on UA-cam calling this style of greenhouse construction 'geothermal.' That is a misnomer. This is not geothermal. This is simply a geo-exchange system.
Exactly. Technically, the heating capacity of this system is limited to the solar energy that enters the greenhouse. They use the ground underneath it as a thermal mass, or a thermal battery.
From what I have read all over the net from people who have done these type of projects, running a single run of pipe would be MUCH less efficient than the way he ran it as several individual runs of pipe. The reason for this is that the air would "bottleneck" with a single run and you would NEVER get the turn over in air that you need to get the results you got. I LOVE his system and it's quite impressive how efficient it is. I suspect that a faster running fan when the greenhouse starts to warm up warmer than the air exiting the pipes would "charge" the ground with heat more efficiently for nightime discharge. This is also an advantage with the multi-pipe run set up. You could never get the type airflow in the system you needed with a single run in order to remove excessive ambient heat.
Makes sense to me. I just know that this works. :)
Engineer here. This is not rocket science; it has many variables, so one doesn't need to overthink it. But, there are several reasons why this is better than a single run of pipe. As for the air temperature and flow rate, here are some basics.
To remove heat from the rock, the air needs to be cooler than the rock. As the air heats up in the pipes, the air will become closer to the temperature of the rocks, so it will not pull out as much energy. So, while faster air seems cooler, it will actually be removing more heat from the ground. Similarly, to heat the rocks, the air must be hotter than the rocks. The hotter the air, the faster the ground will store energy. Blowing the air through faster to the point that it doesn't feel much cooler after heating the ground is ideal, despite seeming counter-intuitive. But, as I said, the details of it don't matter. It will work well enough either way. As he said in the video, you don't want to burn your fans out.
The biggest issue is that, if the air leaving the pipes is too close to the rock temperature, a certain length of rock may not be being used to heat or cool the air, basically being wasted. It would be like never charging your phone battery over 60% or something. But, that doesn't seem to be the case here
I am not allowed to have a structure this size because of the HOA guidelines but I wanted to watch your video and see how you built your greenhouse and pass it along to my brother Jack who is going to build one on his land. Thank you for sharing your knowledge and experience with us sir. I would need a smaller version so it cannot be seen by my neighbors. God’s blessings to you and your family 👍
You could do similar set up with a much smaller building, would be a lot cheaper to pull off too
thank you so much for all your videos! subscribed immediately. thank you for further strengthening the community!
EXCELLENT WORK. I am building right now, and your information is SPOT ON.
If you think its spot on your in for a big surprise when you get done installing it.
@@JohnGuest45 Vague reply with no follow up.
@@Jarrett_Hagar
Show ldspreppers designs to a hvac engineer and he/she will point out why its not going to work very well.
@@JohnGuest45 TY,,, wish I knew more about your comment ! I only want to do this one time,,,,, any help would be appreciated 👍 kinda new to the green house building,,,,,,,,,
@@bustersmith5569
Hi Buster,
If you examine the design in the video you should be able to spot quite a few things that will limit the airflow. For example, having 10 tubes protruding into the bottom of a barrel is not going to provide a smooth transition for the air.The air from the fan may enter some of the tubes but most of it will impact on the floor of the barrel and travel back up where it meets the air coming down.. If the tube ends were flush with the floor of the barrel and radiused, the fan would deliver a lot more air. The system fan has a free flow of 863cfm according to the spec. If the greenhouse volume is 8000 cubic feet, you would have a turnover rate of just 6.47x per hour. For effective cooling you should design the system for a turnover rate of at least 20x an hour. In the spring when the mass is at its coolest, you can run a turnover rate of 45x an hour before the air exiting the tubes rises above the ground temperature. If the air temperature exiting the tube is the same as the ground temperature, you can be sure the full length of the tube is not being used to transfer heat. Its important to note that for best energy efficiency you should run the fan at a speed that keeps pace with the incoming gains. Its better to run at slower speed constantly than flat out intermittantly. Higher flowrates are required in late autumn when the mass is warmer which results in a smaller temperature differential and therefore less heat transfer. The thing to remember with these systems is it isnt how long the air spends in the tubes, its how long the entire greenhouse air volume spends in the tubes. Most systems use excessively long tubes which limits the amount of air you can run. I guess it comes from the notion that long tubes and low flowrates are the only way to provide sufficient dwell time for the air to heat up in the tubes. I use short tubes in a unique arrangement which provides efficient heating and cooling. I designed the system to handle a turnover rate of upto 60x an hour. Most of the installations that were around at that time were using the recommended 5x and didnt have sufficient fan power to test higher turnover rates. The turnover recommendation has more recently been increased to 12x which is better than 5x but still low for effective cooling performance. The bulk of the heat stored in the mass comes from cooling, not the earths core as some would have you believe.
Great Vid Thank you for all your time ,i am in upstate NY lake geourge region zone 5 A, can you please shed your thoughts on if radon with this type of pipe system has any Radon issues to the inside air quality?Thanks Rich and God Bless
40:00 I don’t understand why he said you want to pull air into the intake from higher ( hotter ) if using rock, but to pull cooler air from lower if using dirt. It would seem like either way you’d want to pull the hottest air. What an I missing ?
if you would have ran the tubes under ground to a header instead of capping off the bottom row would it have been better for pumping the air into the green house or do you think it is better to heat the ground. Looking to build a greenhouse this spring just trying to get the best possible construction so i don't have to do it twice lol.
43:10 setting the fan speed by measuring warmest air is not necessarily optimal, due to heat not being the same as temperature. It may be confusing to some. (If you visualize a solar collector heating a pool, you might understand that the hottest water flow means less water which might also mean less heat).
What is the reason for the different pipe intake level for soil vs rock?
Right you want maxiumize heat Q not temperature. Q is T times mass of air.
Very well detailed thanks a lot
best heat exchanging is laminar flow not turbulent but for conduction you are right increased surface area conducts more
Just saw this posted, and not even having the chance to watch it yet, I had to say THANK YOU! Can’t wait to see it.
Can you share the link for the fan that inflates the two plastic? Thanks for the video!
I plan to do dirt geothermal with perforated corrugated tubing. Should I be concerned about dirt, or bugs getting in the tubing underground? What would keep the dirt from getting in?
Why you didn't use a big manifold to connect all the 10 pipes?
Why did you not digg down the greenhouse around 1.5 meter
Really like geothermal greenhouse just not sure it is something worth spending the money on for one in Central Texas. We don't get many freezing nights but the brutal summers tear up the plants. Really like you deer netting idea, definitely will do that. Glad to see your back posting videos sir.
You can also use it for cooling that's what I'm doing on mine I'm up at four thousand foot 13 miles from the desert and I'm going to be 80 to 90 degrees all summer and I have a glass ceiling on mine so I'm going to need to cool mine more than eat it but it's also going to work for heating during the winter which is highly beneficial
@@nicholasbecker3559 Do you ventilate first? Or would ventilation let out the cool air you get from below?
The geothermal brings in air from the outside and then runs it through and then yes I have ventilation Vents and holes up high where that will let the hot air out bring in fresh air in cooling it and so it getting fresh air and it's also circulating fresh air and pushing the hot air out it works okay I mean the room is working great but the cooling aspect of it is not as good as I hoped but it was worth a try I'm probably going to put an AC in there for next summer
@@nicholasbecker3559 hey thanks ! What location are you? How deep were your pipes?
@@TheRainHarvester San Diego County
Five and a half feet.
Does give the cooling I need.
Because the roof is all 1/4 inch glass.
So alot of heat.
We have a USDA cost shared high tunnel and we’re told we were not allowed to have a climate battery and we had to grow in the ground and not in containers.
You don't have any water issues with the perforated pipes??
Why don't you pit a filter at the inlet to avoid dust and insects coming in the tubes?
Have you noticed a difference in the amount of air coming out of each tube and the temperature? Just wondering if more air is blowing thru certain tubes as they are shorter or a more direct route for the air (less air resistance)
You could probably add a blocking object to equalize flow. Might decide how much to block, not on airspeed, but temperature from each pipe.
What if you run into ground water when you dig?
i appreciate you sharing your expertise.
is the greenhouse tape bad/ why do you not recommend it? thx
You must also know that according to experiences done by a university, to maximise the heat exchange in the soil the air must stay between 3 and 5 secs in the pipes. Less than 3 secs the heat exchange will not be completed and more than 5 secs will mean that your pipes are unnecessary too long. That is why some basic calculation are mandatory to get the most efficient system.
39min in, what is your reasoning why you wouldnt want to pull the hot air from the top of the greenhouse into the SOIL version?
Also, do you have an anemometer to measure the CFM coming out of the pipes?
There shouldn`t be a lot of difference in the air temperature. if there is the sytem isnt moving enough air. I find it amazing that folks spend thousands on the installation but have no idea what its doing. Meters are cheap these days, typically less than a hundred.
ua-cam.com/video/u9VYHcL5cdQ/v-deo.html
@@JohnGuest45 totally agree.. if there is that large differential...you need to add a circulation fan. I have meters for days haha. All about that data.
LDS prepper, at 0:14 what is that edging between the gravel and grass made from? It looks like my raised bed material (on my UA-cam).
I am confused as to why your pipes are not all connected? Seems like it would be more efficient to have your intake be a continuous loop to your outtake giving max time for the air to be heated? Perhaps I am mistaken but in the model it looks like the input pipe are simply capped after running the length of the greenhouse?
Anthony Webb This one is more like an open circulatory system, similar to an insect, rather than a close circulatory system similar to a mammal. It floods the open space between the rocks to heat the whole bank of things. It’s not intended so much as to have good air flow as it is to have good thermal heat transfer. Hope that helps.
The ends are capped, forcing the air to exit via of the perforations will severely reduce the amount of air you can move through the tube per unit of time. If you limit total airflow, you also limit how much heat you can move into the mass per unit of time. The air wont flow evenly through the rockbed, it will take the path of least resistance.
I am about to lay the black 4" perforated pipe, but am very concerned that the rocks will crush it. What pipe specifically should I use. Is all 4" perforated pipe basically the same? Or not?
Crushing isnt normally a problem, when correctly installed you can drive heavy machinery over it. Perforated pipe is the same in terms of its purpose which is to allow water in and convey it to another location. It isnt designed to let water out, easy to confirm by checking where the perforations are located. If you pour some water into the pipe you`ll see that water gets trapped at the bottom of every single corrugation with no way to drain out. It will have a negative impact on the heating and cooling performance.
So basically you are making the geothermal greenhouse for the purpose of warming the greenhouse to the temperature of the soil. I need to know in the summer to cool the warehouse what do you need to do and if the solution is similar what would the temperature difference be between outside temp and inside temp.Thanks
Thank you for the links, I will visit the green house supplier, and I can use the fan speed controller for the exhaust from the wood stove that is channeled through a mass heater that I built in my green house.
I like the idea of a geothermal system that maybe affordable for me, with the usda cost share program.
Does the usda packet only cover kits?
In Vermont a grant qualified 'high tunnel' has no concrete and no electricity either of those constitutes a greenhouse.
Nice, detailed video. Thx.
Can you share with me where the US government can help cost share my geothermal green house. Love the content!
Do you have any temperature measurements to see if the air circulation actually provides a benefit?
Do you know or think that there is a benefit to going deeper than 4 feet? I am considering doing a aquaponics system by digging a 10 to 12 foot basement with the fish in the basement and the plants at 2 to 4 feet below grade. I would put the geothermal system at 14 to 16 feet?
Can this system also be used to cool the greenhouse in summer? Thank you for the video I will have to see if I can make it work for me.
A correctly designed system will heat and cool. Its important to remember that a system that is not great at cooling the greenhouse is also not great at transferring heat to the mass
@@JohnGuest45 thanks
Great information on geothermal design.
I plan to install soil geothermal this year. Could 4" corrugated pipe be bend on 10" radius (20" between trenches)?
Could the S-shaped trench be made with Gasoline Drill and Trencher?
I like that you give us the recommendations with experience as some people tell unreasonable theory (5x to 20x greenhouse air exchange), your experience prooved my thinking on minimal required circulation, (with too high airflow condensation in pipes goes away and the efficiency drops) and I like a quiet greenhouse.
Thanks
Matej Kotnik Yes, I just put in this last week and it can make about a 8” radius bend without kinking.
@@joshualruby Thanks for great information, i didn't get notified for your anwser, so i foud it after a while.
i would recommend keeping the tubing as straight as possible with no tight bends as it will impact on the amount of air you can run through it. Serpentine layouts should be avoided at all costs.
Another idea on the inflation fan is to put a geothermal tube in tha ground and pull from that. The ground should dehumidify the air as well as warm it up so as to help with temperature modification and stability. Or so I think and understand. Ty.
Is the greenhouse still going?
Is it possible to incorporate rain water harvesting in this greenhouse design?
Did you keep a record over this past winter (November 2020 thru February 2021) of the outside vs. inside temperature? Also how cool did the greenhouse actually get down to at night this past winter? Thanks
Thank you for this very-useful information! It is much appreciated. I didn't see a dehumidifier in this greenhouse. I'm guessing you don't need one because the condensate should leak out of the tubes and through the rock which should cause it to dissipate into the soil. Is that correct? If so, I'm wondering if I use the soil method with rock under the tubes maybe I wouldn't need a dehumidifier. What do you think? I'm not sure how much rock would be needed. 2"? 4"? Would it be the same amount as is used for a french drain?
I need to put a dehumidifier in this greenhouse. Something I haven't done yet. I'd put 4 feet deep of rock the entire foot print of your greenhouse to have enough heat sink to hold the heat over night.
A well designed system will cool and dehumidify the air without the need for a seperate dehuey.
🛑DO NOT INSTALL A DEHUMIDIFIER 🛑. INSTALL AN ❤️AIR to WATER HEAT PUMP😎
JUST THINK OF THE USES FOR 80 GALLONS 160 DEGREE WATER😳😃😃😃😃
Why roll up the side walls, what is the purpose or advantage to that?
Cool in summer. On 90 degree day which is max limit for growing any plant inside the greenhouse can easily be 130 farenheit
@@charliemagoo7943 makes sense, thanks
is it possible that the pipes will fill up with water ?
Very excellent! Thank you.
What about your local water table levels, will they not flood your underground air space?
By far the single most informative video on Geo thermal that I have watched to date. Thanks David
Great and informative as always. I was just about to pull the trigger on the greenhouse described in the mittleider book that Jim Kennard has in Idaho. Wondered if you had any thoughts if it was a good design? Or if I am better off with the kit you describe in this video. Thanks.
Hallo Sir, from Ukraine, Kiev.
I've watched your video till the very end, thanks for this detailed video.
Just wander if You may know, should I put isolation under the pipes IF, I am going to put my greenhouse 2 meters underground and the underwater is about 2,5 meters below ground level.
So, my plan is put water isolation, heat isolation, pipes on some gravel and cover it with sand, to serve as thermal system, put the isolation material (foamed sheets), make a waterheated floor on the top.
Would be pleased to hear from you.
Cheers
Roman
Great video. Question, I am thinking about building a similar setup but it's close to a river so there's a high water table and I don't think perforated pipe would work because it'd just fill with water. Do you think a system would work with 4" solid pipe in place of perforated to keep the water out?
A high water table will tend to take the stored heat away from the system. Raised beds can be used to increase the effective depth. They also reduce excavation costs.
I'm in Eden and was hoping you could cover a winter planting list
What about strong winds?
He said he has strong winds and it is built strong enough to withstand them (60 mph+).
What about radon? Is that an issue? In iowa and Missouri radon is an issue from the ground. Curious if that is a concern.
Great video I heard your name come up from another video watch watch two out three or four different subscribed channels on geothermal and I went ahead and did it kind of wish I would have watched some more but I had enough information to build my own and seems to be working still got to finish it and test it but I appreciate the knowledge and nice video thank you
Would you please add to your details, where in the country and what zone you live in?
Why in swing not out... I'm thinking in terms of interior usability and ventilation
That's how I did mine since I would have no plants to interfere with the door swing on the outside.
Nice tour. Thanks.
DO you have a link to the greenhouse kit you purchased? I clicked your link but just goes to main page on website.
I am in the northeast and certain regions have natural radon gas in the soil. I imagine perforated pipe would pump this radioactive gas into your greenhouse. Has anyone commented about your design and whether this could be problematic?
If this is a concern in your area certainly test for it.
how much electricity does it take?
WHAT IS NECESARY FOR ZONE 8 ( DALLAS ) ?
This video and the one before this one about your greenhouse are very helpful. Lot's of great information. I am getting ready to build my geothermal greenhouse this fall and this info is super helpful and very much appreciated.
Thanks for sharing. I may have missed it, but what is the type of plastic you used in regard to thickness, the material type, and so on?
What temperature is it stable at?
Any rodent pressure?
Is that mystery tree a Paw Paw?
QUESTION: Is there a reason that you don't use the geo pipe air to cool the greenhouse during 90 + temperatures?
Thanks
His design doesnt allow sufficient airflow for effective cooling. The real kicker is that its the cooling that provides the lions share of the heat stored in the mass. A system that doesnt cool, doesnt store as much heat either.
@@JohnGuest45 Thanks JohnGuest45! I always wondered why the "battery" did not work in reverse. Like having a row of water barrels for table support should keep the greenhouse warm during winter and cool during the summer.
@@newgardener
A well designed system will provide effective cooling. Water barrels start losing heat as soon as the greenhouse air temperature drops, not at 2am when you need it most :)
@@JohnGuest45 Can you give us an idea of what would need to be done differently to achieve sufficient airflow?
I know you are really proud of this design and all, but physics says you are running the system backwards. In order for air to release the heat energy efficiently, you need to have a drop in pressure. You need to put the earth battery under a slight vacuum. You always want to be pulling air from the coldest part of the system, not trying to push hot fluffy less dense air down. By pulling the air on the cold side where it is dense, you will be pulling twice as much air from the top of the greenhouse. And storing twice as much energy in the process. Pressure = Heat. But suction = cooling and heat storage.
You wont create negative pressure in a perforated tube :)
I have a high water table... Can I use non perforated in the same manner to avoid flooded tubes?
You dont want to use perforated pipe for geothermal applications In most designs.. this guys just so happens to call for it. Also a smooth surface interior pipe is a bit better for air movement so it will save you power and ware and tare on your fan.
@@Templarzealot89
A corrugated tube has roughly twice the surface area of a smooth tube, you`ll need to install twice as much.
His particular design here, with the rock fill, appears to actually *require* that the air leave the tubes through the drain holes, filter through the rock exchanging heat, and then re-enter the second set of tubes, and then return to the greenhouse. So in this particular specific case no, it requires those perforations to work at all. However if you're using the more 'normal' kind of system that has a continuous set of pipes from entry to exit, the in theory yes.
But the problem is that you can potentially get condensation in the pipes. With no pipe perforations to let condensate out, you're creating thousands of tiny troughs for water to collect, and mold to form, which is not good.
VERY cool thank you
i like the green houses. i am also going to be a resident of SE Idaho again in two weeks after being gone for 30 years. i will be living 25 miles east of IF. could you e mail me, i have some questions about the how to of the green houses. i have checked on some designs in western nebraska and would like to compare it to yours before i build. thank you
8:25 please provide a link to the "4 in. styrofoam".
How do the lower pipes provide heat with capped ends?
I believe he lets the air leave the upper tubes through the small drainage holes, and then the air goes through the rock bed, in the space between the stones, enters the lower pipes through those drain holes, and then out those pipes. It makes direct air contact with the stone, which probably makes for better heat transfer. It also probably hugely increases the friction losses.
The 10" intake tube has a cross-section of 78.5 square inches. One 4" diameter tube has 12.56 inches of cross-section area, and ten of those is a total of 125 square inches. So the intake tube is under-serving the laterals based on raw area. But given the amount of friction losses he's likely working with, he probably needs that 60% extra lateral area to compensate.
@@mattmanning1572
You are correct, massive losses with no guarantee the entire mass is being utilised. If the system was completely lossless, (which it isnt) the fan isnt capable of moving enough air for a greenhouse that size. Its hard to believe someone would spend thousands of dollars on an installion without running the numbers first.
@@JohnGuest45 Also, his measurement was temperature to determine the fan speed. But heat (btu) should be measured to determine the best flow rate for heat transfer (not temp).
@@TheRainHarvester
That is correct but in ths case it doesnt apply because his tubing arrangement.wont support that kind of flowrate. The other thing to consider is many installations use basic thermostats to control the fan which dont take account of the mass temperature. This can lead to a situation where valuable heat that could have been stored is not stored and another situation where the thermostat calls for heat and runs the fan even when the mass has no useful heat to give :)
When the penny finally drops and folks start to design systems that work, i wont have to keep trying to save folks from making an expensive mistake by following the advice in vids like this one.
Do you ever have problems with the wiggle wire tearing into the plastic?
Nice detail looks great. I have a similar setup it sure helps here in mn
Awesome! I see lots of dog videos on your channel. Love to see some greenhouse videos too. 👍
@@LDSPrepper Thanks for looking. I do a greenhouse video about every week, but more to belp my memory than anything. Great job
Just got the first layer of poly on mine this week... I'm concerned about the lock wire channel not being large enough to handle 4 layers of poly on the ends. How did you do this? Deeper channel?
Love the meadowlark singing. My favorite bird song. We rarely have them. BTW, Nice job.
Regarding your method for determining the optimal speed of the fan: It isn’t just the outlet temperature of the air that matters, the volume of air exchanged is also important. Consider this thought experiment. Case 1: the air exiting the tube is hot but the air exchange flow rate is low. Case 2: the air exiting the tube is not as hot but the air exchange rate is higher. Case 2 may actually warm the greenhouse air more than case 1 as a greater volume of heated air and thus a greater heat flux transfer occurs under case 2! Assuming that your greenhouse air is well mixed, a better location to measure the temperature of the air is at the drum at the end of the greenhouse at the OPPOSITE end to where the warm air enters the greenhouse from the buried tubes. A thermometer placed at that location would better account for the total amount of heat being conveyed to the greenhouse and allow you to fine adjust the flow rate on the blower to its optimal speed. Hope that helps.
In practice, the optimum fan speed is one that maintains the desired greenhouse temperature :) In terms of maximum heat exchange you should aim to maintain a temperature differential over the full length of the tube. Most installations are unable to achieve this due to poor design. Most dont have temperature sensors to measure the mass temperature, which, when you consider the cost of an installation, beggars belief. A low flow rate will result in the air cooling to ground temperature in the first 10ft of tube and then coasting the rest of the tube without any further change in temperature.
Ccalculating the heat transfer rate is relatively easy if you know the inlet temperature/RH%, the outlet temperature / RH% and the flow rate in CFM.
Its important to understand that RH% plays a major role when it comes to heat transfer.
@@JohnGuest45 What does RH% mean?
@@marticastlewarr5723
Relative Humidity. It plays such a major role in the system performance, but rarely gets a mention.
Was following ok until it got to pipe laying and then got lost as it looks like none of the pipes are interconnected
He appears to be having the air leave one pipe through the drain holes, and filter through the spaces between the stone, and then enter the other pipe, then back into the greenhouse. So he's probably trying to get more contact with the heat storage media, this way. It probably increases the friction losses tremendously, but it may be a good way to overcome the slow-ish thermal transfer properties of the pipe. The stone probably transfers heat at least 3x as fast as the pipe itself.
@@mattmanning1572
He`s getting less contact with the mass because the air can/will choose the shortest path. You also need to consider the rock may only account for maybe 60% of the storage volume due to gaps, so 40% of the "thermal mass" is air. You want the air to connect with as much of the mass as possible, you also need to reduce the frictional losses to get the most from your fan or you are wasting power and $$. The contact time in respect of how long the air spends in the tube isnt important, its the amount of time the "entire" greenhouse air volume spends underground. If you send a cupful of the greenhouse air through the tubing once a minute it may be warm but its still only a cupful per minute which wont make an ounce of difference to the greenhouse air temperature.. If you could put the entire greenhouse air volume underground once a minute, that would increase the greenhouse air temperature. The designs in the video reduce airflow, pretty much the exact opposite of what you want..
The serpentine layout he recommends is a complete debacle, ua-cam.com/video/T-fa_5co2FM/v-deo.html
The losses on a 300-400ft length of heavily corrugated tube with 9x 180 degree and 2x 90 degree bends will be immense.
LOL Your cat is driving my dogs crazy.
Did you ever notice , no matter how much money someone has, they always want you to " donate" something to them?
I prefer to draw air out of the ground rather than to blow it in. So my blower is on the exit side. Here’s why? Instead of air entering through plastic drainpipe risers, I have a manifolded flat-black passive solar collector made out of metal downspouts against the north wall of the sunken greenhouse that heats the air before it is drawn into the ground. I also have a vent on the manifold of the collector that allows the rising heat inside the collector to exit directly into the greenhouse (and bypass the ground loop). This allows the greenhouse to be heated up quickly if needed. At night, there is no heat being added by the collector, so cold air from the floor of the greenhouse is drawn in through the ground level intakes of the collector. Thus excess daytime heat is stored in the thermal ground battery and is retrieved at night when it is needed. Another advantage to blowing air out, rather than blowing air in is that, if you live in an arid climate, you can attach a DIY evaporative cooler to the blower and cool the air in the greenhouse quickly to prevent heat stress and wilting or blow it across dry ice to add some CO2 to make the plants grow faster. Yet another advantage is that blowing humid air into the ground causes condensation and the moisture fosters the growth and proliferation of mold. Sucking air out dries the soil preventing this condition from happening. Though I haven’t tried this, you could also use the blower to generate electricity or even to spread powder or add air to a compost heap or to a bubbler, or to supercharger a rocket stove, etc. (as long as this will not burn up the motor on the blower). If you live in a cold climate, to add additional heat, I recommend making a ground battery out of a couple of thermal solar panels, two loops of pex pipe (and for added safety, I’d use heat tolerant pex for the loop connected to the panel), a water pump, a junkyard truck radiator with a fan (or create a pex pipe radiant floor attached to the bottoms of pallet walkways), and a glycol water mixture for the fluid. The high heat capacity of water makes it a much more effective fluid than air for transferring heat to the thermal battery. Store it up all Summer and then draw it out all Winter.
blowing humid air into the ground causes condensation and the moisture fosters the growth and proliferation of mold. Sucking air out dries the soil preventing this condition from happening.
You are mistaken. I`ve had my tubes in the ground for 13 years, mold is not an issue. Air takes the path of least resistance. Blowing air creates a positive pressure, any leaks will be seen as high resistance paths compared to the tube exit. Sucking air creates negative pressure, any paths near the fan will be used to pull air in, this includes permeable soil. The idea that the soil will dry if air moves in a certain direction is just plain silly. If the air is warm and moist and the tube is cool, the air will drop to dew point forcing water vapour (a gas) to change phase (to a liquid) and condense out inside the tube regardless of whether the air is being sucked or blown. If the inlet air is cool with a low RH% and the ground is warm and moist, the RH% of the air will increase inside the tube, also regardless of whether its being sucked or blown. The limitation of any system is how much air you can run through it.
@@JohnGuest45 Where I live the ground temperature below the frost line is approximately 50 F. Summers are hot and humid (90 F and near 90% humidity). Pumping hot humid air into the ground will definitely cause condensation and if not drained out, the accumulation and pooling of water and ultimately mold growth.
@@JohnGuest45 True the direction of air flow does not cause drying- I never said that it did! Soil does however dry if you blow low humidity air across it and condensation does occur if you blow warm moist air across a cool surface. That’s not silly, it’s physics!
@@JohnGuest45 sorry, I meant to say sucking cool air out into a warmer greenhouse. That will dry the air and hence keep the pipes condensate free.
@@resilientfarmsanddesignstu1702
You will not prevent condensate forming in the tubes because a greenhouse full of transpiring plants isnt conducive to a low humidity environment. If you measure the temperature and RH% of the inlet and outlet air along with the CFM, you can calculate how much condensate is forming in the tubes. If you calculate the difference the outlet air makes to the entire greenhouse air volume in terms of lowering its RH% you will find its not a significant amount. The main factor is the amount of airflow you have available and, in most cases, the system design is the limiting factor.
I think it's awesome that you're growing trees in a greenhouse! That's my dream!
I also want to do geothermal too!
What you want is shcs (subterranean heating and cooling system) specifically designed for a dome greenhouse.
I love the info. Just wish it was more condensed or less long winded.
0:44 In and I'm already loving what I'm hearing. By 19:32 I'm feed up of repetitions....
at least around here, the NRCS high tunnel program requires crops to be grown in the ground or bed, not pots.
I believe that is the regulation for the first year. After that here are no limitations.
@@LDSPrepper I just got one- it's for 5 years.
Nothing really planted in the ground. You have a big investment. What are you planning to grow? Will you sell commercially or just eat it yourself?
We are in the Rexburg area and wondered if we could come and see your set up and ask questions in person? I also sent you a message on your facebook account. Thanks
At $2k a pop, those are some very expensive fruits ^_^
one thought, you said the cost of stone over just dirt for thermal storage was not worth the cost. One could dig out as you did, and instead of dirt or stone drop in 44 IBC totes full of water and deck over them. Water has more BTU storage capacity than either of the other mediums. You could use either a conventional solar collector, or a row of IBC totes above ground on the south side painted black, and a circulatory pump and link the above ground ones to the in ground ones to charge them with heat during the day with the pump running, and have the pump off at night heating with just the radiant heat. check this page out for the heat capacity of water per gallon. www.engineeringtoolbox.com/energy-storage-water-d_1463.html Great video, and awesome green house! ETA, I dont know what latitude you live at but 120F in february is incredible! Idaho......now I am really impressed with the efficacy of your setup!
From a plants perspective, the IBC`s wont provide any of the benefits you get from usingh soil as thermal mass. There is much more to it than just storing heat.