Feed tube outside, riser and radiator/mass inside?

I have tried asking this before, but have not yet gotten a definitive answer...or perhaps I am wanting to hear an answer that is simply not forthcoming.

My father has a pole barn/workshop where he frequently uses solvents and sprays paints, many of which are flammable.  He has, or had, an old wood-burning stove in it, but was afraid to use it due to the open flame and very high heat.  I watched a video by Matt Walker where he built a RMH outside of a sauna, if I remember correctly.  It led me to wonder if a rocket mass heater could be built where the feed tube was just outside an exterior wall of a structure, with the burn chamber passing through the wall, and then the riser/radiator/manifold/mass all located along the inside of that wall.  I know great caution and planning would be required to insulate THOROUGHLY around the burn chamber, to protect the wall from the extreme heat produced in that part of the heater.  That would keep the flame completely outside of the structure, but you'd also have very cold air feeding the fire, much of the time.

Another option I just thought of is building the entire stove inside the pole barn, with a small false wall/enclosure around the feed tube area.  That would hide the flame from flammable materials, but you'd still have the challenge of running the very hot burn chamber through a partition.  

Is this just a bad idea?

Seems doable.
The section of wall it passes through could be metal or masonry.
J tubes benifit from short burn tubes, so your barrel and riser should probably  be just on the other side of the wall.
I would put the feed tube   on the south facing exterior wall and cover it with  a lean-to greenhouse, filled with stacks of drying wood.

Hi Jason,   I have my rocket mass heater installed in a pole barn/workshop where we constantly use/store paints, gas, chemicals, wood (chips and dust) and other flammable materials. At first I had the same concerns but after running it for 5 years now, I feel very confident in its safe use in such an environment. However, with that said, don't mistake my scenario as a drop in replacement for yours! I only tell you this as a suggestion from my own personal experience and safe work ethics.

 

You could do it, but I'm with Gerry. all sorts of paints and aerosol are used around my rmh and my old double barrel wood stove (soon to be a new RMH). Never had an issue.
I think that a feed tube outside would be a bother to load and that really cold air would not help your burn temps.
Have you considered a batch box RMH ?
No open feed tube to worry about .

I agree with Thomas. A Batch Box with a tight fitting door would be a good solution.

The added bonus is the amount of heat that the glass on a BB door puts out. It quickly warms the space while the main mass of the bell/bench/whatever gets up to temperature.

I had not thought about a batch box RMH, but I think my dad's concern would still be the open flame required to light it.  I should state that these are not my concerns; the understanding I have gained from building several rocket stoves, used for outdoor cooking, has made it clear to me that a properly built RMS or RMH has very little in the way of open flame concerns and is easily as safe as any other heating method available.  I'm not sure why my dad is so cautious, but he has been heating with a propane-fueled salamander prior to using any paints or solvents.  As with any convective method of heating, he is frustrated by how quickly the shop becomes cold again.  When I showed him some of the RMH options and how they could reduce his cost and allow him to heat over a longer period of time, he seemed very interested, but has those concerns about the open flame.

Hi Jason;  Can be frustrating getting people to accept a RMH.  Keep trying he may come around. Show him pictures of a batch box's , then show him a J tube, explain the differences. Maybe he will hear you...

You know Jason , if your dad would go for it .. your idea of a wall / partition would work.  Insulating with modern ceramic products would be easy.  You just need to convince your dad to move forward from the past.. I say that knowing that I am a horrible old stick in the mud when it comes to change... and hate to move forward myself.
One idea would be to show / convince one of his friends how rmh's work .... then let his buddy talk him into it...
 Good Luck he can be convinced.