Greenhouse 8" Rocket Mass Heater Plans

Greenhouse 8" Rocket Mass Heater Plans

This is one of our newest plan sets, with damp-resistant detailing for indoor-outdoor spaces.  

This plan includes three or four example layouts, both conceptual and proven plans, and notes on how to take advantage of solar or passive-solar gain as well as wood-fired rocket mass heating.









Support the authors (and the Permies empire) by buying these plans here!

I'm not sure if this is the right one for me. Can I scale it down to say 10 feet? Or if I keep it at 40' can I incorporate turns to cover a shorter but wider area?

I'm hoping to heat the floor of a shed/dehydrator as backup on days the sun doesn't provide enough heat.

Cj Sloane wrote:I'm not sure if this is the right one for me. Can I scale it down to say 10 feet? Or if I keep it at 40' can I incorporate turns to cover a shorter but wider area?

I'm hoping to heat the floor of a shed/dehydrator as backup on days the sun doesn't provide enough heat.

Hello CJ,
You could certainly scale things down.
If you add more turns, you need to shorten the overall length a little bit, say 5 feet less for each additional 90 degree turn.
So you could do 4 passes of 5 to 7 feet in length, and cover an area a little larger than a king-sized bed.
Or the same space vertically, as a heated wall, with the exhaust travelling upwards.

We've helped people build oversized rocket mass heaters for lumber-drying kilns; I think you could do a small one for a dehydrator.
You might also look at the 6" rocket mass heater plans - such as the Annex 6" or Daybed 6" RMH plans.

Let me know if you've already bought these 8" plans, and I can email you a diagram and parts list for scaling things down to 6".

Yours,
Erica Wisner
Erica@ErnieAndErica.info

Erica, I'm considering doing something like this to heat an aquaponics system either building a 4x8 raft tank on top of it, or using the mass as one of the sides of the 4x8 tank.  The builders guide has been helpful and great for radiant room heating.  I'm trying to get that heat into water without playing the boom squish.  Do you have any insight?

Best,
J.Dible

Jeff Dible wrote:Erica, I'm considering doing something like this to heat an aquaponics system either building a 4x8 raft tank on top of it, or using the mass as one of the sides of the 4x8 tank.  The builders guide has been helpful and great for radiant room heating.  I'm trying to get that heat into water without playing the boom squish.  Do you have any insight?

Best,
J.Dible

One of our beta testers was doing micro aquaponics, so the pictures in the plan set show how he prepared his bench for part of his tank setup.  He built the mass to support two or three of those rigid liquid totes, so the tanks rest on tiles directly above the pipes in the mass.  (Brick walls support the paver-like tiles, the remaining mass is softer cob/sandy stuff infilled around the pipes.)  This setup is located along his greenhouse wall, where both mass and water also collect sunlight to reduce heating needs.  

Another option is to include a variation on Tim Barker's water heater on top of the barrel, to produce on-demand hot water for piping to other tanks.  That's described in Appendix 3 of the builder's guide.  
In this case, I'm imagining just a big pot of water, like a giant canning kettle with a regular (non-pressure-canner) lid, and a coil of pipe dropped into it to run pressurized domestic water through the hot-water bath.  This system allows the water directly over the heat to boil (which it likely won't, unless you work harder to insulate and trap the heat), but even if it did, minor spillage rather than boom squish.  The higher pressure in the piped water raises its boiling point slightly, so it won't boil until all the other water has evaporated, and even then, the heat transfer would be pretty limited if the coil is up off the bottom of the pot (like you get with a canning rack).  

Don't skip the pressure relief valves anyway, but Tim's system seems more owner-buildable than most other attempts I've seen.  I like the canning-pot size because you can take it apart and clean / de-scale it as needed.

How you dribble hot water into fishtanks without killing the fish is your deal - I'm guessing there's a lot of known mixing technology and thermostat controls available.  
I probably would not recirculate algae-rich water through small pipes for re-heating, however. It seems likely to cause blockages and complications with the pressure differentials, which are a necessary safety factor not just a convenience.  
You might look at a secondary heat-exchange system where you just drape some hose or pipe from the heated water lines into the tank, and don't let the waters mix.  Again, researching what kind(s) of hose or pipe can do this without killing fish is up to you.  I think fish can be sensitive to copper, and synthetic hose will often off-gas when hot.  Might be some type of Nalgene tubing, or stainless steel, could work?  

Those are my thoughts.  If you get something working to your satisfaction, I'd love to see pictures here.

Yours,
Erica

That one the dog is sleeping on, is the one set up to take 4x4 foot IBC rigid 'totes'.

Hi there! I'm interested in these plans, I just have a couple of questions.

The first picture says "duct-heated raised bed" but the other pictures are apparently from somekind of an aquaponics system platforms?

I'm planning to build (oh well, assemble) a greenhouse this summer and would like to have some kind of heating system for it to extend the growing season a bit. My greenhouse will be about 33ft+10ft and I'm wondering if I can fit this kind of system in there.

How are the plans for the duct heated raised bed..? The first picture shows that the duct maybe goes by the side of a raised bed.. Is the idea to build a bench-like side from bricks for the raised bed, and the duct goes inside it?

Thank you for the assistance!