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Denis Allan

Posts: 2
Reply with quote  #1 

Good Morning Everyone. 

Denis LeBlanc from Ontario.  I have a 16x24 greenhouse that is unheated.  Inside I have an insulated grow bed that essentially is a self irrigating planter box with 80 gal. of water with drain tile lining the bottom as well as a 4" pvc tile.  The pvc holds apr 25 gallons of water.  I'd like to connect that pvc pipe to a 3x6ft hot water solar panel to put some heat into the grow bed thereby preventing freezing.  

I'm just trying to keep the temp above 36F to keep the plants in a vegetative state to keep growing.. 
The issue is to have a pump in the water system that will not freeze without having a second system in place, like heat tape, to keep everything from freezing. 

I wanted to install a low flow pump but having the system as a draw down, or open loop means the pump would also have to drain back to the bed to prevent freeze damage, but the pump would also have to be able to draw water up about 12-16" from the garden bed.

The only work around I see is installing a submersible pump inside the 4" pvc pipe where it would get some protection from freeze up.. 

Does anyone have another suggestions as to how this might work.. 
The entire system is water based in case there is a leak into the grow bed.. 
I can provide some diagrams and pictures if this would clarify this project build.. 

Denis Allan..


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Posts: 3,063
Reply with quote  #2 
Hi Denis welcome to the forum. Hopefully one of the greenhouse guys can help, otherwise look here: https://simplysolar.supporttopics.com/?forum=333286
Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay

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Posts: 1,109
Reply with quote  #3 
Denis would a system based on RV antifreeze using a heat exchanger inside your PVC pipe be OK? As designed there would be no mixing of the antifreeze circulating to the solar panel with the water in your bed but if there was a leak I believe RV antifreeze is non toxic.
Both temperature rise and airflow are integral to comparing hot air collectors
Denis Allan

Posts: 2
Reply with quote  #4 
Good morning. I had concidered a closed loop system but not for RV antifreeze.
The aspect of organic gardening for four seasons and having antifreeze,even RV antifreeze pissibly mixing with 38cubit feet of potting soil mix wouldn't be good which was the motivation to design a draw down system. I will reconsider it but just having something like antifreeze inside the greenhouse and in the grow bed goes agsinst the grain of what I' m trying to achieve with organic foods.

Thank you for that input.....Denis

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Posts: 143
Reply with quote  #5 
12v Pv panel directly wired to a pump like this-  https://www.amazon.com/ZAOJIAO-Brushless-Centrifugal-Submersible-Circulation/dp/B07G9ZPRK8?psc=1&SubscriptionId=AKIAILSHYYTFIVPWUY6Q&tag=duckduckgo-d-20&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B07G9ZPRK8

Submersible Pump 16ft lift

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