Is exterior feed possible for RMH?

We've yet to start building my husband's trappers shed, so have plenty of time to plan the design. Will be approx. 12'x16' plus a 4'x16' covered porch area.

Here's a rough drawing of what I'm hoping to do. Husband has asthma, so I'd like to eliminate chances of smoke inside. Is it possible to create a Rocket Mass Heater with EXTERIOR FEED?

Not a rocket scientist, but guessing this will affect the ratio of intake to output.

I am wondering this same thing, but my application would be a sauna.

Jerry Ward.... I'm also interested in a RMH Sauna project for our place.

You have a few issues to work out--

There is a limit to the horizontal feed and you don't really have a lot of room between the barrel and the feed to put much of a wall and it has to be completely non-combustible.

You have put the barrel right in the corner of the building so you are losing a lot of the heat radiating directly onto an exterior wall.

You have to make sure the wind doesn't blow across the feedtube and create a vacuum to backdraft (like blowing across the top of a bottle).


Not saying it can't be done, just saying it has issues to work through.

The issue of why this doesn't work well is addressed in the early part of this thread: "RMH, fresh air intake, why suck out warm air from inside?" by contributor Adam StJohn.

Vicky Barton : While my fast answer would be- ''No, why don't you find someone who lives with a Rocket Mass Heater RMH, and see smell for yourself how smoky
their house is or isn't there are about 6 other Forum Threads where you can ask for an invite to visit !

Having said that, I Am sending you to - 'rocket mass heater - Finally completed and it works! - (rocket stoves forum at permies) watch for the link for pictures! -
Notice that this system has a horizontal wood feed system, since this was 1st made, some members have made designs similar to this, that rival the efficiencies of the Vertical Feed
J-Tube style RMHs that are the standard that other stoves get measured against !

For the Good of the craft! Think like Fire, flow like a Gas, Don't be the Marshmallow ! As always, your questions / comments are solicited and are welcome PYRO - Logically, BIG AL!

Sure appreciating all the info and links. Am jotting notes and hope to get something solid to start this project in spring 2014.