# Heating your home with Compost



## Coastal (Jun 27, 2013)

After seeing a few videos, and thinking about the systems based on the Jean Pain mound, I am really leaning towards heating my new off grid house with compost.

For those that don't know....in its most basic form...poly pipe is coiled up in a huge compost pile, water is run through the pipe, and it absorbs the heat from the compost which reaches 140-150 degrees F. The piles create heat for 12-18 months, which means hot water for 12-18 months with no fuel, no chopping wood etc.

I searched on here and found nothing, so here we are. My plan is to build a new building, install pex for radiant heat and have a compost pile dedicated to floor heating, and a second one dedicated to domestic hot water.

The property we are buying is 160 acres of mountain and field, and currently has no utilities. 






Anyone try this? I'll have wood heat for backup in case it's a terrible failure...lol


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## Sentry18 (Aug 5, 2012)

Never heard of it before, but it looks very interesting.


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## cqp33 (Apr 2, 2012)

I would say it would work. My compost piles get so hot they will cook cut grass into ash if i don't get enough carbons in it, been there and done it! so yeah i would imagine it would work good, here is my concerns with it though.

-Compost piles need turned, how will you turn it to keep it from burning up and to keep it cooking if you have a coil in it some where?
-Ideal compost pile temps 135-160 degrees F, if the pile stalls from being saturated or over cooks and gets above that nominal range will whatever material you are using for a coil handle the higher temps in the range of of 170-190 degrees F which would be on the top side of a "hot" pile?

Just a couple of things to consider, but yes I see this as possible and you have my wheels turning for a possible SHTF water heater!

This link is a pretty good compost page, they are recommending turning a pile 4-5 times in a 15 day period.
http://rodaleinstitute.org/turning-compost-by-temperature/


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## cowboyhermit (Nov 10, 2012)

It is a good heat source for sure, I don't recall ever seeing a house (in particular) getting most of it's heat this way. Lots of prototypes and industrial/agricultural uses. 

If designed for it, hydronic heating systems can be adapted to accept heat (and/or cooling) from a variety of sources (a HUGE plus imo). With some doing it is possible to have the same system able to gather solar, geothermal, hook up to a wood boiler, use gas, electric etc. Then on the other side you get the ability to use that heat for whatever you want hot water, household heating, etc.


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## Tirediron (Jul 12, 2010)

I would think that there would be a finite amount of heat that you could recover before you pull too much out and stalled the reaction. As to the stirring, we have never bothered with stirring compost or manure piles and they both turn to rich black soil, hopefully no one tell them they need to be stirred


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## Coastal (Jun 27, 2013)

Absolutely there is, the compost pile would have to be sized according to the amount of btus you require. With a radiant heat system, the cooled down, but not cold water would be recirculated back into the pile, so it wouldn't take as much heat as say having a 4 hour shower. Where all the hot water is warmed up well water and would go to waste.


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## Woody (Nov 11, 2008)

Interesting!!!

I do agree that it would be hard to manage the temps for that long of a period, 12 to 18 months. 6 months, very doable.

The center of the pile is where you would have the greatest heat. The lower you go, heat is lost to the ground. The higher you go lost to outside temps. Yes, they might be minor but all losses add up. That brings us to a few questions.

Replacing the water used. For heating, you would want to recirculate the water, so it is still warm when it enters the system. That means a closed system so no nice hot tub outside with it. If you are taking that hot water out of the system, it needs to be replaced with cold water. If you take out too much heat, it is like turning the pile, it takes time for it to heat up again and start working.

I would think having a reservoir in the pile would be beneficial. In Vermont and Canada, when it gets cold out, you are drawing a lot of heat off the pile! Granted, 300' of black pipe holds a lot of water, but still, it is cold out and a lot gets drawn off. Anytime you slow down the compost action by cooling, it takes time for it to get going again.

Maybe even a heat exchanger in the reservoir, in the pile? You recirculate the heat of the pile within itself, and the reservoir, and just draw heat off the reservoir. That way the pile maintains a more constant temperature and continues to work.

Then there is the yearly maintenance. You need to make a new pile every fall. It is one thing to take a bunch of brand new pipe, lay it out and shovel stuff over it into a pile. It is a bit different to have to disconnect all your fittings, drain the system, dig it up, put it somewhere, relay it somewhere else and do it again. You are going to need a bunch of extra couplings, and lengths of pipe, and replacements for all the valves you break, replace all the kinks or shovel holes you make..... 

I'm not saying it isn't a great idea!!! I'm just thinking you might want to take time to think of a way to make it an easily reusable system. Something like... 

Have your 500 or 1,000 gallon reservoir in the middle, with in/out piping facing North. Have several layers of 1/2 or 3/4" black pipe around in in layers, in a 'frame', with all connections facing North. Each summer you dig the north section, to uncover all the connections. You can then dig down to the top layer of pipes and lift it out as one unit. Dig to the second layer, same thing.... Set them aside, build your new pile and reassemble. You might not even have to cut new pieces of pipe between layers if you leave a good 'loop' to allow for settling of the pile.

I had "hot boxes" for several years in NE PA years ago. Digging a pit, layering in green manure and hay, building cinder block enclosures and attaching old wooden storm windows was the easy part. Disassembling to redo them the next fall was a whole different thing!!! If I had to add digging while worrying about hitting pipes or fittings, it would have been a nightmare.

Again, I see it as VERY DOABLE!!! Maybe it is just age that makes me wonder how can I do it so it is a lot easier to undo and do again.


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## Coastal (Jun 27, 2013)

I agree, the way most people do it looks like a one time affair, then a total pain to disassemble and rebuild. I envision a central heating core, perhaps even using copper pipe coiled around a welded rebar frame. When the season or pile is done, disconnect the inlet and outlet, hook a chain to the rebar heating tower and pull the whole copper coil system out with an excavator. Load up composted material with the machine, and install new compostables on top of the heating tower once again.

These guys seem to be the most involved in testing and presenting info about it:

http://compostpower.org/home


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## Coastal (Jun 27, 2013)

I just emailed compostpower and got an almost immediate reply with some cool info:



> thanks for reaching out. Yes this is totally do-able and yes I've helped others do similar projects. Actually just last week we did a project very similar to this in Michigan to heat a 1000SF straw bale home.
> 
> 10,000 Btus/hr with 110-130F water for radiant floor loops would be enough to meet most of your heating need for this size house if it's well insulated. A mound that can put that amount of heat out doesn't have to be that big, 50 cubic yards, 14ft by 20ft in dimensions. We've seen that level of sustainable heat output from very simple Jean Pain style mounds (wood chips/mill shavings/bark mulch/saw dust as the primary feed stocks) where one mound stays hot for 12+ months so you just rebuild it every fall (it can be torn down/rebuilt with fresh materials in one day).


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