I came across this plan for a green house night store heater/dehumidifier in Hydroponics soil less gardening explained by Les Bridgewood.

Basically it's an insulated box filled with stones painted black that you duct hot air from the GH through.
He goes on to explain that the black stones absorb the heat allowing the air to cool and the water to condense out it and collected with a simple wick system.
In the cooler night time the heat stored in the stones is released back into the green house.

It may or may not work so before I go to the bother of building one I thought I'd see what you guys make of it.

[simos]

Looks promising, but I wouldn't expect to gain more than 3-4 degrees in the immediate area around it. Applied to even a medium sized greenhouse, I'd guess you'd have to scale the design up a bit.

I know people that use black garbage cans filled with water as cheap heat sinks. Sorta a first line of defense against the cold, if you will. They have thermostatically controlled propane heaters too, though, so I wouldn't count on passive solar heating as a be-all end-all.

Here's an interesting (albeit overpriced, IMO) product I've been looking at for the same purpose: https://www.growerssupply.com/farm/su...;pg105449.html Food for thought, at least.

Cheers

Ah it's more the dehumidifying aspect of it I'm interested in, I'll be using a compost/solar based recirculating system to heat the beds.

https://www.motherearthnews.com/Renew...g-Compost.aspx
^ a smaller scale of this one, all I really need is to heat the beds to 14-15c so it should work well scaled down.

Do you think it would be effective as a dehumidifier?

[simos]

Looks like it could. I guess you'll have to build it and be the guinea pig to know for sure. Personally I plan to battle the ill effects of humidity with excessive air circulation, but it would be great to have a more direct recourse against the root of the problem.

Funny that you bring up the compost heating system - I suggested it in Nomaad's thread a couple months ago when he was talking about running a single monster sativa in his geodesic dome GH all the way until thanksgiving. He said that he'd seen a neighbor in Central America struggle to make a similar system work year after year without ever quite getting the desired effect. I think the consensus among the people in that discussion was that PEX tubing would be the best option for keeping the soil warm. Then again, I'm sure you'll get some kind of positive gain from the system...

Suerte

[geopolitical]

This works, but we do it a LOT smarter. Pipe the air into the planting beds through buried drain pipe. Excess humidity condenses in the relatively cooler soil as does excess heat. You need a LOT of pipe & airflow for this to work well though. It also reduces watering and outside air exchanges for humidity by quite a bit. May not work as well in a very warm climate however, we're subarctic here. Worked substantially better in the 2nd season, so I suspect a buried insulation skirt would probably enhance it as well.