How Double Layer Greenhouses Supercharge Your Growing Potential!
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Greenhouses are revolutionizing the world of agriculture, and double layer greenhouses take it to the next level. Join Curtis Stone as he guides you through the intricacies of how double layer greenhouses work, exploring their unique features and benefits.
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About Curtis Stone:
Curtis is one of the world’s most highly sought-after small farming educators. His book, The Urban Farmer, offers a new way to think about farming𑁋 one where quality of life and profitability coexist. Today, Curtis spends most of his time building his 40-acre off-grid homestead in British Columbia. He leverages his relationships with other experts to bring diverse content into the homes of gardeners and aspiring small farmers from around the world. Learn more at FromTheField.TV.
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Thank you for the information. There sure are a lot of inventive folks commenting and overthinking answers for problems that do not occur. I appreciate the simplicity.
these " How I do things " vids are great
they have answered a lot of techy questions I have had
Interesting! I met a man named Richard Nelson, who invented a system where you insert very thin (dry-cleaning type poly)tunnels between the layers at each end of these ducts there was a fan, on which was adjusted a screen, drippping with dishwashing soap & water was dripping . The result was to fill the ducts with gazillions of tiny bulles. Once done with the insulation need, just blow the bubles up against the creen at the other end, recouperating the solution in a closed circuit.
But what was truly mind blowing in his project was that he had placed the greenhouse structure over a surface made of a water retention bassin filled with large rocks opn the inside of the external layer, he had water slowly dripping from the apex. Water was thus heated, and stored underneath the structure.
At night, in the desert, very cold temperature is the rule. Richard's soap ducts system insured a superior insulation against heat loss, thus conserving and slowly consuming energy stored under the greenhouse. I don't know what happenned to Richard or his designs. At the time the Canadian based company he owned with his wife was called Thermagrow.
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Does the fan say anything about how many cubic feet per minute/ CFM or the revolutions per minute RPM? Thanks
You rock Curtis, simple and quick
Great video! I work in the greenhouse business and we have installed blower using inside and outside air. Not much difference with condensation but drain holes are helpful. There are pressure relief valves you could use instead of a open pipe. The wiggle wire - great invention!
Does the double layer have any benefits during the summer?
Thanks for all the great information
great video! more details on how you fix the hoses to the poly in such a way as to support the hose/blower. The question that would be helpful to answer for us is how many CFM does the blower provide? Rather than current draw, what the Cubic Feet per Minute rating is the key variable... Again, thanks for sharing this!
Very simple yet very effective...thanks for uploading...need to build a largish (6' x 10') unit for the front of my house for winter flower and shrub protection here in Alabama...great insight now.
I'm building a SSG off-grid, so will try a fully sealed double skin with a tapped condensation draw-off and a pressure switched on/off for the blower.
Does this work for hot climate areas?
This is a great system. They sometimes add pressure switch on it to stop the motor when the pressure builds up between layers.
... there’s a damper lid on mine to reduce the pressure if needed ...right on the fan ... ready to change my Polly this week myself ... have a great spring here in zone 6 ...
What do you do with it summer? how do you deal with heat?
whats the temperature difference between the outside and the inside of the greenhouse during the winter?
I used to have a huge greenhouse but I am working on a new one and would love to have a business like you. I have 3 acres but maybe 1 acre is usable because of the giant trees and a pond. Anyways I picked up a great blower like this at a yard sale this past weekend for $2......I think I paid $70 for my one before.
that’s an awesome idea ..i’m thinking of this with a solar panel to run the fan….silly question but don’t you need the sun light to get through the poly?? or is the diffused light enough ??
Hello, great job! I have a question about the exhaust. Are you just pushing back the air between the layers and what vent are you using? Thank you, sir and once again, amazing!
You made a wise choice with the double-walled polyethylene. The pricey Palram Thermaglas 8mm twin-wall polycarbonate is rated at R-1.72, whereas your setup is in the neighbourhood of R-5.00 It's difficult to argue with that!
If the inlet to the blower was being taken from outside. Would that solve the moisture between the plastic . which I assume if you have air and moisture you will have some type of mold growing. Working an indoor garden is important to have fresh air 2 cycle and control the humidity in the growing area. I assume that's the same with a greenhouse. Thinking about putting my own hoop style greenhouse in.
Excellent info. Lot's of practical ideas fot not a lot of money.
On my greenhouse, I've given up on those little fans. They have crummy little sleeve bearings and just do not handle the long hours of running. But this fan is optimized for producing high static pressure and you won't find a small fan with better bearings that will replace them. I went with a larger fan that replaces the 6 small ones that my double bay greenhouse used to need. (it has poly walls). I have a whole box of little junk fans (that had to be replaced in the middle of the night etc) if you want them.
Fantastic! THANK YOU for sharing! I too have been struggling to budget for the clear corrugated roof panels, so this will be my more affordable solution!
Thanks for your comments! Appreciated. All the best with your gardening/farming. Sincerly, Sunita - From The Field Support Team
Merci from Montreal, Canada.
What is the CFM of the blower you are using?
I wanna try something like this in Quebec. You think it'll be too cold? I want to buy your book too, is it still available? Thanks for all you do!
Curtis I have a question about the benefits of using this in the summer. Does it have a benefit in decreasing solar heat gain or does it actually increase solar heat by trapping?
I can’t find an answer anywhere and hope you can help.
I'd like to see what kind of chanel Lock you used to hold the poly and how you hold the poly up
Hi Curtis, thanks for all your great information! Regarding inflator blowers if you draw your air from outdoors you will not get the condensation between layers! Thanks for being such an inspiration, keep up the outstanding work!
This is not true from every other grower I've seen. If that works for you, send me a picture of your greenhouse. Nobody I know in a cold climate does that.
Ok, will do. I'm in NH using a Harnois oval tech with blower mounted outside under a small metal hood. Second Harnois has rigid poly roof with inflated side roll up walls. Again, blower mounted outside. Never had condensation between poly film regardless of temps.
Ok, I would love to see how that is played out.
Do you have to rack the snow off the top layer to keep that bubble up?
No. It melts on contact.
where did you get the fan from? thank you
This totally make sense! Thanks, Curtis :)
Very very EXCELLENT! Does the plastic have UV protection, and if so how many years is it rated for? I purchased some greenhouse plastic end pieces (at a big discount from Grower's Supply) for my low tunnels that had a coating that allowed sunlight to enter but reflected back into the greenhouse the long-wave heat radiation. Do you buy special greenhouse plastic or just inexpensive local stuff? Your Northern location does not have the intense sun radiation like the South. What is the longest you have had plastic up without it falling apart.
I am considering this on my greenhouse
Curtis, if you put the fan on a variable switch, you can control the pressure and get the inch column of water needed. This way you won't stretch your plastic over time.
Better to let the blower run as intended and release excess air with a valve
Thank you so much! I am building a passive solar green house in an area of South Africa that has regular frost in winter during the night. Now I was looking for some type of fabric I could use to roll down the plastic cover during the night as insulation. Found nothing so far. Then i revisited your video on the double layer plastic which seems exactly what I need. One concern I had was the fact that it's a curved area - until you moved to speak about your second green house you planned on covering, because that has a curved area too. You didn't seem concerned about that fact. Is it not necessary to put any spacers between the two layers? you just cut the sheet a bit longer then the first one and the blower does it all?
What happens to the greenhouse when it snows a lot outside? I can see that the snow would help with insulating however does it put stress on the greenhouse? And how do you deal with that? Also how do you deal with the inside of the greenhouse if it drops a certain temperature? Does that R factor stop the ground from not freezing?
came across your channel today and was viewing this video. a lot of things got clarified for me Sir. One question , may I know the thickness of the poly I must use .Is 200 micron a good quality ? Please clarify.
Curtis, do you use different types of poly for the two layers? If so, how did you determine what types to use? I'm looking at buying poly for my hoophouse soon. Thanks!
Would be great to show the temps outside verses inside. Looks great & gives me some ideas for winterization
How's your mold ,is this the first year you have done this ?
Hello. Awesome information. Thank you. Where do you purchased the poly? How long will it last?
Great information and build. Thank you for sharing.
... best of luck with your new greenhouse... hope you have an easy to get to place right by the driveway...easy to get in to and haul stuff too ... I like the heavy weed barrier plastic for flooring...but really a dirt floor works ... figure out how to save and transfer rain water for use in the greenhouse ...going on year 24 with my hobby house ... 10 X 20 Polly hooper ...
Where did you get those galvanized 45,s you used for your hoops?
hello thanks for video. Can this greenhouse resist hail ?or it will be broken?
So is this only a winter thing or good for summer as well?
Very informative, thanks buddy.
What was that little thingy hanging there?
Can the fan be on the outside? do you loose heat by pumping the warm air into the void? Or would it cool the greenhouse down too much during the winter f you blew the cold air into the void?
If you take air from outside instead of in the greenhouse for the fan you will get less condensation between the layers.
Greenhouse air is usually pretty humid
Could you achieve the same effect as bridging the tubing across panels by doing a couple of bore holes in the wood frame for airflow
Great idea! Congrats Curtin, and thanks for sharing! What difference of temperature can you reach with this system?
@5:05 that 115V AC fan at 0.65A is then 75W, which is 657kW/h per year of 24/7 nonstop running
Can you have the blower with roll up sides?
Sorry I'm late to the party, but I would mount the blower 90 degrees to how you have it mounted. The way you've mounted it now forces the bearings on the fan and motor shaft to ride on the side of the bearing races. This will shorten the life of the bearings, and you'll need to replace the worn bearings or the whole fan earlier, whereas mounting the motor shaft horizontally allows the bearings of the shaft to run in the center of the races. Otherwise, beautiful greenhouse!
Would this allow me to have a greenhouse in the AZ desert when it’s 120*?
Is it possible to do that over poly carbonate?
Another great video. You answered a lot of questions I had on double poly. Thanks!
Hi Curtis, thanks for the videos and the tips about double layer inflated. I have set a second Poly layer in my greenhouse. The system works but I have some points where the gap between the two layer is really big up to 20 cm and other parts is really narrowed. Moreover, I have still condensation in the inside poly sheet. What can be the cause of these issues? Thanks for your support.
condensation on inside is normal in greenhouse. plants transpire
Where can I get one of the blowers?
What poly did you buy in that quantity for less than $100? Is it not UV treated or 6 mil?
How long do the two layers of poly last? Or how often does it need to be replaced?
I haven't found any recent comparisons on youtube comparing 2 greenhouses. 1. unheated double layer inflated vs 2. unheated single layer. There was a study done in 1979 hortscans.ces.ncsu.edu/uploads/o/b/observat_537b7424bc61c.pdf
in summary it basically says in the early hours prior to sunrise there was very little difference in temperature between both unheated greenhouses. The study also highlights a large reduction in direct light from adding the 2nd layer. I have seen others do geo thermal and I can attest personally that the black painted drums being used as thermal mass does great, but I was just curious when singling out the single wall vs double wall if there was any real difference in the hours leading up to dawn.
Do you get bad winds in your area? if so, how do your poly do in high winds? What about your little ones over the garden beds?
How thick is the poly, that you are using, and where did you buy it?
what's the spacing between film sheets? is it feasible to stuff or drape industrial air pillows instead of fan?
drawing the air from outside will help with condensation
another benifit is it acts like a pillow, absorbing energy frim wind gusts.
I could be wrong but I would think filling it with warm air from inside would be better insulation than cold air from outside.
MrFarmer1997 it's about relative humidity
warm air holds more moisture then cold
warm moist inside air when it comes in contact with cold, the moisture drops out.
happens to ships that load in the tropics , thousands of gallons have to be pumped out.
Curtis is in high desert, or semi arid.
he only has a small problem with moist air.
not practical, do you know how much that much double glazing would cost, and you only need it for the winter.
@Robert Slackware You're not achieving any measurable vacuum for 300 bucks with plastic poly sheeting.
With the double layer poly what does your house temp run during summer,winter fall spring?
Did you pull both layers at the same time or different wiggle wire channels for each layer
So it is basically blowing air from inside the greenhouse to the space between the 2 polys to get rid of the condensation and to insulate? If so, does the greenhouse have inlets to let air in?
Use outside air for the blower or you`ll have issues with condensation inside the cavity. .
@@JohnGuest45 Naw, then it'll be too cold in the winter. You want to gain heat. The air in the greenhouse, and in the walls is a mostly "static" volume. It's just with the additional layer of poly, his greenhouse air is not adjacent to cold outside air acting like a perpetual heat sink in the winter.
@@d-rot
If the cover is well sealed it will only need filling once, the rest of the time the blower is simply maintaining pressure. A still air situation is hard to acheive when it involves a flexible wall, every time the wind hits the cover the air inside wont be still. Still air will not prevent convective currents being set up inside the cavity as they are driven by temperature difference. A vertical cavity is worse than a horizontal cavity in this respect. Convective currents act like a conveyor. transporting heat from the inner wall (warm) to the outer wall (cold). I use air inflated poly with 2 seperate cavities (triple glazing) made up of individual compartments rather than a single large cavity.
Curtis, from my research, the max R value I can find is R2. Can you point me to the documentation showing the possibilities of getting R5 ??
There is none that I know of. You're probably right.
Curtis, you pointed to the insulation value of the double walled Greenhouse. I guess that was no surprise when you see modern buildings having double or even triple glazing. My question is: During hot weather, does the greenhouseheat up to the point of harming the plants. For instance, this last week has been 35˚C plus every day. Would that cook the plants?
hi, whats the winter temperatures there?
Thanks Curtis for the run down. I’m in Jakarta urban area and how about 500 sqm of yard. I havre read your books and now prepared to grow hear.
With hot topical weather climate whats the best way to start.
Jakarta? Put a stick in the ground and it'll sprout. I doubt a Canadian veggie farmer in a dry climate can recommend how you start in a humid tropical climate. I think you need to learn from what's growable in your area. Start looking at seed catalogues and checking out more local farmers and markets.
What is the problem if I do it without this fan or without air system
Awesome tips, how would you in your opinion setup a 4×10 green house in 120 degree weather during summer and 30 to 70 degrees in winter?
Where did you buy the poly plastic?
Anyone know what fan that is and where to get it?
On my GH I have 2 layers of poly separated by 1x2 boards on each rafter and stud. The poly is tight so I have a 3/4" gap between the layers. Does this give the same effect as the blower system?
yes as long as the 2 layers don't touch each other.
The blower compresses the air, somewhat, so gas laws say it warms the air, somewhat. Also pressurized air prob'ly has a higher R-value. But you could build the inner layer farther from the outer layer, and achieve whatever you wanted.
so are both layers laid flat together before air insertion
Great video. What kind of greenhouse do you have?
Very interesting concept….
what if you drive that exhaust pipe (3:27) into an underground pipe and then back into the greenhouse? will it work better? what do you think?
Curtis, awesome channel. I like your greenhouses.
Awesome video and very good technique.
Iam from Ladakh it's a cold desert area lies near the Himalayas in India,Here in Ladakh during winter time this states get cutoff from the rest of the country,means there is no supply of vegetables and fruits, people usually depend on dehydrated vegetables and caned or stored food and due to large population the government is not able to supply cheap vegetables to everyone,once a week in Ladakh people get to see vegetables,the situation is really bad.I have planned and this year I'll begin my project to provide cheap and fresh vegetables to the market,if you can help me out in anyway or if you can visit here I would really appreciate a lot and I'll pay for your stay in India.
Hoping to create a better tommorow for our children's.
Thanks Curtis I have learned a lot from you. What do you do in summertime do you still run blower?
If you have holes in the plastic for drainage, how does the air stay between the layers?
Depending on the size of the greenhouse, would you need more than one blower? And Do you leave the double plastic on all year?
First time I’ve seen one of your videos. It was very informative and I get it. My question is, the blower you talked about, is it to strong for a greenhouse the size of maybe 8x8 or 10x10? Thank you
It's a good practice but the air have to be taken from the outside. As you can see, there is a lot of condensation between the two plastic layers. this is due to the condensation of moisture in the warm air that comes into contact with the outer layer.
Thanks for the walk through
I would appreciate a video of the actual installation of the blower into the greenhouse plastic walls. Actually, if you erect another such greenhouse, a video of its erection and covering would be appreciated by me and I dare say, everyone with an interest in such an activity.
Try cold sinks and geo thermal with 4 inch corragated line under under the frost line to use the warmer subterrian air
Awesome stuff. Do you have a video about how your "channel locks" are designed ?? Would help me understand how you sealed it and connects the poly to it
Search 'Wiggle Wire'.
I know this is two years ago but if you could answer the one question I haven’t heard yet.
If you have two layers of plastic how lose do you fit the second layer to create a gap? How big of a gap is the blower creating?
Kurt C good question. I am wondering the same thing
Charlie Hubley it seems that would be the first thing to mention but after watching the whole video the person doing it readily admitted that a viewer knew a lot more than he did. I haven’t found another video yet that has my answer and I’m ready to put my plastic on.
Where did you get the hoses to run the air from one air pocket to the next? Im having trouble finding something similar, that is also cheap.
check out laundry dryer vent flex hose
How much space do you have between the layers of poly?
hello and thanks for sharing do you have another video on the actual construction thanks i live in the middle east where temp can get to low 50c during peak of summer and it would really help if you can share how its done..thanks..so much
Just an idea for free fans.
If you can find a friendly enough furnace installer often times they will have junk furnaces piled behind there shop waiting for the scap man.
Often the fans are still good.
Not only the big squirrel cage but also the smaller draft inducer fan.
Just a thought
great idea, i love how you have reduced your costs with blowing hot air in between the layers of poly