Rocket Mass Heater + Oven?

Hello folks,  I am new here and this is my first post, so please forgive me if I post in the wrong area.

I want to build a 6 foot high by 20 ft long brick or cob wall with a rocket heater to warm the mass of the wall.  The purpose is to trellis citrus trees against the wall like a grapevine (espalier) so that they are flat against the wall and use the wall and sheet plastic to create a temporary greenhouse during the winter time.  

Here is my question:
Can I build a 6 foot high x 2 foot x 20 foot long cob or brick wall with a rocket heater on one end that will succeed in the keeping a 4 foot bed against the wall above freezing during the winter?

Would it work?

Can I add a rocket oven at the beginning so that I can bake bread?

What are the best resources that I should purchase to be able to build this project right the first time?

Hi Caroline, it's been a while, sorry your post got lost! I am not an expert but I will try to respond.  Hopefully someone else who knows more can chime in.

I'm not sure I can visualize what you are describing. It's a 6 foot high cob wall. How are you going to protect the cob from rain? I'm guessing there will be large diameter piping through the cob wall, to allow the heat generated by the rocket to warm the mass of the wall, and I know there are limits as to how many feet a particular sized system (size being based on the diameter of the J-tube) can service.

The most successful systems have the piping go out into the mass and then back again so that the chimney is near the barrel, this improves "pull" of the exhaust through the system. I don't think a normal rocket heater could drive 40+ feet of piping with a 180 degree turn in the middle.

I'm no expert on the RMH side of this either, but from the other side, I'll add these two thoughts:
1. You'd want to plant on the south side, thus this would be where you want the heat, but heat moves from high concentration to low, so I would be trying to make "insulating" cob (lots of straw in the mix) on the north side of your wall, so that the heat from the rocket stove doesn't go to the north side, any more than you can avoid.
2. Heat rises! So I would think that so long as you heat the base of the cob wall, and simply use the upper part of the wall for protection, you should be able to keep the  needs of the rocket heater's ideal pipe lengths within it's limit. I'm visualizing a cob "bench" put vertically rather than horizontally. I'm sure I read somewhere about someone putting a pipe in the back of a cob bench - any chance that was at Wheaton Labs anyone??? The Tepee bench maybe???

It would be helpful if you gave us some info about your eco-system. Locals here grow citrus against any solid wall, and permanently install recycled sliding door glass coming outward from the top of the wall to help trap the heat. Only when we're expecting atypical cold, do they add row cover or plastic hanging down from the glass, and then if freezing is likely, they use old Christmas tree incandescent lights wrapped around the tree for extra heat. I think that trying to replace that electricity with wood heat can be done, as I definitely know of several RMH's installed in greenhouses, although I'm also aware that the high humidity can be an issue.

However, you mention grape vines *and* citrus - I'm thinking their needs are quite different. Maybe you'd be looking at some sort of manifold to direct the heat to one wall or a different wall part way through a burn?

Hi Caroline;
Sorry we missed you earlier. Spring is a very busy time of the year around the north west.
I'm adding your post to the rocket mass heater forum as well as the rocket oven forum.

We do need a location and climate  for your build, as well as more info on exactly what you have in mind.

I'll start by saying, forget using cob outdoors. Build with brick, its much more weather resistant.
Forget piping the heat from your rocket, you want a brick bell to hold your heat.
Insulation can be used to direct that heat where you want it.
I'm sure your thinking J tube rocket as they are very easy to build.
Plan on building an 8".  
Consider building a 6" batchbox instead.  Larger wood laying horizontal ,  burn time of 1.5 - 2.5 hrs , much higher heat output.

Now about having an oven at the same time...  It can be done but... are we baking bread or growing fruit trees?
Multi purpose RMH's are few and far between.
Trying to maintain temperature for baking could considerably change how long you need to burn, to heat your mass.