My Greenhouse Project

Hi everyone. Sorry for the panic posts on some of your guys posts. I’m really new to rocket mass heater and I think I’m gonna do more research before building one in my greenhouse. Here are my challenges, Im in Wisconsin zone 5b, I have a 100 feet by 30 feet hoop house and I’m going to double layer with plastic. My first question, is it possible to have an underground bench about 110 feet long with a bypass and possibly a heated gas going into the pipe to prime for draft? What type of rocket mass heater should I get? I would like to build a chamber so I can fire my ceramic. I still have more questions but maybe we can keep a thread going. Thanks so much for all you veterans out there willing to help.

Vong

I don't think a rocket stove of any type is going to work for firing. The temperature swings to rapidly, would likely cause major cracking and possibly violent deconstruction with shrapnel. AKA steam exploding ceramic  

Hey Von!
Here is a link to some rocket kiln information:
https://permies.com/wiki/177379/harvest-clay-and-make-pottery#3030406

Here is a link concerning your long bench idea:
https://permies.com/t/59302/Length-exhaust-pipe

If I were in your position, I would try building a short, temporary, above ground bench powered by a   j tube style rocket.

Truly so helpful!!  Thankyou sooo much!

William Bronson wrote:Hey Von!
Here is a link to some rocket kiln information:
https://permies.com/wiki/177379/harvest-clay-and-make-pottery#3030406

Here is a link concerning your long bench idea:
https://permies.com/t/59302/Length-exhaust-pipe

If I were in your position, I would try building a short, temporary, above ground bench powered by a   j tube style rocket.

Hello all, I wasn't sure where to ask this, but this seems like the most relevant thread I could find. I also have a greenhouse/high tunnel very similar to the description in the OP. My greenhouse is 30' wide by 96 feet long in middle Tennessee zone 7b. But my question is a bit different: floor space in the greenhouse is precious and we try to pack as many plants in as possible so we can be in production year round, but surrendering some space to a RMH that allows us to keep the space actively heated would open up more plant options. I have unlimited amounts of cardboard I can scrap out of the dumpster next to the greenhouse. It is a dumper for the food bank and homeless shelter we grow food for and it fills with cardboard 3 times a week. I have one goal with maybe two options. The goal is to build a RMH with a very small horizontal footprint. A 5' by 5' area max. Option 1: I don't really want radiant heat because I'm afraid I will degrade the greenhouse plastic. So, how would I build a more vertical mass? I have lots and lots of lime stone. I think you all have said to not have mass directly against the barrel and especially not touching the top of the barrel. I have lots of cattle panel to build kind of a gabion mass around the J-tube and the barrel but how would the ducting work in a vertical mass maybe 5' by 5' by 8 feet tall? Would that be enough mass to store the heat without wasting any? Would the ducting come out from the bottom of the barrel, go to the bottom corner of the gabion, put an elbow in the corner that is pitched up at 15 degrees or so that has a straight run to the next corner and the next and the next kind of in a square corkscrew? or can the ducting run up and down in an S shape? Option 2: I have 5 aquaponic systems that hold about 400 gallons of water per system. So, I have about 2,000 gallons of water I could store the heat in. I know about the boom squish problem and I would keep everything an open loop. I've read that wrapping the barrel with copper pipping that gets really hot could create some chemistry issues that could be toxic to my fish, but I don't know that to be true from experience. And even if I did wrap the barrel in piping I know I'd probably still be loosing alot of heat radiating off the barrel that the copper pipping would miss. I only bring this up because it could potentially take up much less space since it would only be the J-tube and the barrel paired with the water instead of building a vertical mass around the combustion parts.

Thanks for all the feedback!

Nathan, if I were building a rocket stove for this space I would build a bell along the north wall of the greenhouse and use the top of the bell as a place for more plants.

The energy in wood derived solid fuel is mostly proportional to its density,so if you are planning to burn cardboard I would go for a very large j-tube or batch box rocket stove that can fit a lot in at one time.
This 8 inch J-tube that Uncle Mud could be ideal.



It has 6 whole barrels end to end as as a bell, and the area above the riser is insulated, so most of the heat is directed into the bell, instead of radiating out the tops and sides of the barrel.
They built theirs outside, and covered it with a hugel mound.
If you built yours indoors you could surround it with pallets so the sides were vertical,or just put pallets along the north side, and let the south side be sloped.
A 6 barrel bench is about 18 feet long.
Sizing the j tube up to 10 or even 12" could enable an even longer bench.

If the goal is to heat aquaponics water without changing the chemistry, stainless steel coils should do the trick.
If you station the sump tank above a heated bench, a homemade heat pipe could move the heat from the bench to the water.
Heat pipe video:
Check out this video, "diy heat pipe"

I have been looking for that Uncle Mud video!

That is at Wheaton Labs, right? How is the rocket hugel doing now?

It did take some effort to find it!
Hopefully someone knows if it's still intact and operable.