My fan-coil active thermal mass greenhouse is finally operating!

Another phase change material to consider is glycerin.  If you can find a biodiesel maker I think it's considered a waste product.

It is about 130 square feet.

I've thought about glycerin, but apparently even a small amount of contamination with water turns it into anti-freeze that won't solidify even below freezing, so I'd probably have to buy it pure.

Oh, that's interesting, I hadn't dug into it enough to learn that.  I wonder if it still does the phase change at 63 degrees despite not freezing solid?...

I guess it isn't quite as bad as I thought.

https://www.engineeringtoolbox.com/glycerine-boiling-freezing-points-d_1590.html

At 5% water it freezes at F 46. At 10% water it freezes at F 29, at 20% water at F -5

So I guess it depends on how much water biodiesel glycerin would have in it.  

And that might be a benefit if you want to bring down the phase change point...

1.  Is there a way to determine how much water is in glycerin by-product of bio-diesel?
2.  Is there a way to get the water out? (safely!)

Yes, I have a free source of it, but it didn't phase change the way we wanted it to.

I'm not sure, but maybe you could measure the temperature at which it freezes?

As far as getting the water out, I'm not sure.

I finally got the IBC tank into place in the greenhouse. Before I fill it up and figure out how to connect the pump and radiator, I'm trying to figure out how to keep algae from growing in the tanks. Any thoughts?

Gilbert Fritz wrote:I finally got the IBC tank into place in the greenhouse. Before I fill it up and figure out how to connect the pump and radiator, I'm trying to figure out how to keep algae from growing in the tanks. Any thoughts?

First thing is to keep the water in the dark. I the water going to be in a closed loop and not open like before?

Right, it is going to be more or less closed, just running from the IBC to the radiator and back.

Well, it has been a while. I strained a muscle in my abdomen and haven't been doing my gardening work this past year. But I'm finally ready to start planning my next steps with the greenhouse.

The mouse problem is serious and ongoing. I've decided that the structure simply isn't well sealed enough to be a real year-around greenhouse; critters and pests just build up. (The way I build the retaining wall means that there would be no efficient way to block out critters.)

So I'm planning to use it as a two season (Spring and Fall) greenhouse with a removable cover. During the Summer, I'll use it as a giant trellis for squash and other vines, with shade loving crops underneath. In the Fall I'll put the plastic on to extend some things, then take it back off over Winter to let the cold weather deter pest build-up, and then recover it in the Spring for seed starting.

I'll still use the IBC/Radiator set-up to balance temperatures when the cover is up. When the cover is not up, I'm thinking of using the IBC as a giant Kratky hydroponic tank!

Gilbert, thanks for the great example of "observing", "problem solving" and "changing plans" based on how things are REALLY working, rather than how you'd hoped they'd work! The idea of it being a summer trellis is wonderful - you might end up with a nice shady spot for either greens that like it a bit cooler,  or humans that need a shady spot to sit or possibly both!

If you could PULL the air thru the radiator you could make better use of your radiator I would think.  At least some of the air (with the fan behind) is being pushed against the radiator itself.  With the fan pulling air from the front side, you have a bonus of more air circulation.  A vehicle pulls the air though - if it was pushing the air, it would be working against the natural airflow of the moving vehicle. I realize this is an old thread, but maybe food for thought for anyone looking into this type of system.  

Hi L,

Welcome to Permies.