Greenhouse question for Shawn

Hi Shawn! I have your book in my wishlist and so I'm thrilled you are here answering questions. I was watching your video clip of greenhouse tips here on permies and am very interested in the hot water tubing you use for heating seedlings. Is the water heated with electricity? I recall seeing a hot water tank in there, but I wondered if there is a way to use the heated water from the black barrels being used for thermal mass?
While on the greenhouse topic - do you know of a resource that discusses the various types of greenhouses - I want one for our farm [to be] and there are just so many choices/styles it is a bit overwhelming.
Thanks!!

Hi Laurie, Thanks for your interest in the book. We use 1/4 inch EPDM tubing for our benches and connect it to a schedule 80 pvc header. They also make 1/2 inch tubing for long runs. Hydronic kits are available or build your own. The pipes are connected to a hydronic heating system that uses a small circulation pump. The great thing about hydronic heating is you can use a variety of heat sources to provide the heat. We have an electric water heater for backup and get most of our heat from compost piles. We also have a small solar water heater attached to the system. The solar system can melt pex pipe if the system turns off and then comes on after superheating inside the solar exchanger. Best to mount the solar heater before your hot water heater or some other kind of tempering device and run copper pipe.

We don't use the water barrels to heat the water and they're more for passive heat. If you use metal barrels be sure to line them with a drum liner to prevent rust. This would probably make connecting the barrels with pipes difficult so I would use plastic barrels and uniseals to connect. We do connect the hydronic heating system to ponds inside the greenhouse which are similar to 55 gallon drums but they're easier to insulate by using extruded polystyrene below the pond liner then floating a solar pool cover on top. The ponds absorb solar energy during the day and a heat exchanger connected to the hydronic heating system can pump extra heat into them so they can be used as heat storage batteries. Since the compost/electric/solar heated water is always hotter than the pond, heat always moves towards the cooler pond water. My guess is that the water inside the barrels would rarely get hotter than the hydronic water so the barrels would extract heat. It would be interesting to see what a solar only system could do that used a series of connected barrels. If the solar heated barrels were placed below the benches on a sloping greenhouse maybe a thermosiphon could be developed to pump the water without an electric pump. I think your on to something Laurie! When I have to replace my barrels I'll have to swap them out with plastic ones and try it out. Thanks for the idea.

Regarding the greenhouse book the best one I've seen is called "Integrated Greenhouse Systems for Mild Climates." It's a little pricey but I was able to check out a digital version through our University Library. My book might give you a few ideas as well . Bending your own metal hoops can save a ton of money but you don't get the steep roof that helps shed condensation and snow.

Shawn,

Please share the URL of the video that she mentioned.

BTW. Thank you for your answer here. If your book is anything like your answer, it is going to be great.
Looking forward to getting one because this book supplies information that meets a need, we need to be able to see Permaculture in a hands-on way.

Sincerely

Jan Cooper, Adult Ed Garden Educator

Hi Jan, Lorenzo put the video in his book review post titled "The Bio-integrated farm by Shawn Jadrnicek and Stephanie Jadrnicek" it's also on the chelsea green page http://www.chelseagreen.com/the-bio-integrated-farm

Jan Cooper wrote:

Please share the URL of the video that she mentioned.

You can see the video: here

Thanks Shawn! I have to admit I really just thought I missed something in the video but when I thought about it for a minute, I wondered if the barrels themselves could use a few more functions to help them reach the magical 7! If you do try it out, I hope you will post it here on permies. When I get a greenhouse (thanks for the reference and I am most certainly going to get your book) I'll give it a go and report back here. Somehow I think (and secretly hope) you will beat me to the punch!

laurie branson wrote:Thanks Shawn! I have to admit I really just thought I missed something in the video but when I thought about it for a minute, I wondered if the barrels themselves could use a few more functions to help them reach the magical 7! If you do try it out, I hope you will post it here on permies. When I get a greenhouse (thanks for the reference and I am most certainly going to get your book) I'll give it a go and report back here. Somehow I think (and secretly hope) you will beat me to the punch!

Hi Laurie, when you've finished the book please feel free to post a review of it here
It is always great to get the book review grid grow with reviews from all members of the permies community