compost heated greenhouse?

[ArcticCat]

Anyone here have a greenhouse or hoop house in which you heated our supplemented some of the heat using compost bins? This would be done inside the house.

[bwaynef]

I haven't yet, but I'm planning to try it this winter. I've got a 6x8 (hobby) greenhouse and overwinter a few things, or will sometimes use it to provide a false spring. That said, I'm not expecting to keep it at 70°F all night, I just need to keep it not too far below freezing (30°F+) at the coldest point in the night (usually early morning).

I'm planning to alot a 3'x3'x3' space for compost made up primarily of stored grass clippings, oak leaves, coffee grounds, and as many kitchen scraps as I can amass between now and when I get started. (Its not regularly below freezing here yet.) I've also found horse manure that I'd like to get if I can figure out a way to transport it, as well as municipal "compost".

I've seen mention of having a register of sorts of copper or even plastic tubing that snakes through the compost and out into the greenhouse wherein water circulates through the tubing in the compost and out into the greenhouse releasing/distributing the heat a little more evenly. That may be overkill in my situation.

What are you (or others) thinking about doing (or, better yet, doing)?

[saltmarsh]

I thought compost piles used oxygen and created co2 as they composted. You might want to rethink this one.

[bwaynef]

Originally Posted by saltmarsh

I thought compost piles used oxygen and created co2 as they composted. You might want to rethink this one.

Is this in reference to:

Originally Posted by ArcticCat

This would be done inside the house.

I made the assumption he'd be doing it in the greenHOUSE. If that's the case, and your assertion is true, then the plants in the GH would have additional CO2 available while the Compost pile would have additional O2 available.

I knew the bacteria that causes the compost to heat up used Oxygen, but I'm not aware of the makeup of its outputs.

[saltmarsh]

It is in reference to being done inside. The compost pile should act as a heatsink also, absorbing heat on sunny days and releasing it at night.

[biscgolf]

i have read a bit about it and it seems like a good idea- i'm not sure that i have the greenhouse space to pull it off though...darn thing is already packed.

[Cole_Robbie]

Originally Posted by bwaynef

I've seen mention of having a register of sorts of copper or even plastic tubing that snakes through the compost and out into the greenhouse wherein water circulates through the tubing in the compost and out into the greenhouse releasing/distributing the heat a little more evenly. That may be overkill in my situation.

I think it would work if you did all of that, but with all of that work and expense, it would be easier to make a different heating system.

The plastic tubing you mention is a type of pex that is built to mimic the heat transference properties of copper. They use it in radiant under-floor heating. Of course it doesn't work quite as well as copper, but it is ten times cheaper.

There's also "active solar" where 6-8" drainage culvert is snaked through a bed of gravel. During the day a small fan moves the hot greenhouse air through the gravel, heating it. When the sun goes down, the flow of air is reversed. Moving air back up through the warm gravel provides heat at night.