Am I dreaming that I can put a small scale RMH into a 20.5 x 81 inch space?

I need some help here....again.

I would really love to put a small RMH into the space in front of my fireplace. The space is 20.5x81. The problem is that we rent and I can't do any real changes. It has to be low impact and able to be removed when we move out.

I have read an account where someone built a RMH in front of a fireplace, removed one of the glass panels and vented up the chimney.

I have a 30 gallon barrel (18.5x29.5) and about 100 clay bricks and 8 8x8 firebricks.

A few difficulties.

-Small space 20.5 x 81
-Rugs surrounding tile pad of fireplace
-Basement underneath, so would have to investigate the weight bearing load.
-Not much clearance possible between barrel and slate fireplace. Would that be ok since it is a stone fireplace?
-Don't see being able to build it at the site due to 4 year old twins and rugs and nice stuff (Dad gets messy when building too). Twins would enjoy building but would create an unrecoverable mess. Might need to build it and move it in. Possibly make it in two pieces and bring them in? Wheels/dollies/pulleys. I created a picture of a possible idea. Hopefully it is easy enough to see what I was going for. Although first time using Google Sketchup. Two pieces that would be pushed together and somehow sealed then vented out the fireplace.

Have people been successful with RMH units using less than 6" vents, aka <28.27in2.

This would not be used as our primary heat. But since we have a lot of deadfall in the yard around us I would like to try to use it as an additional form of heat to keep heating bills down. Our house has terrible windows and even though I have plastic sealed many of them the walls aren't well insulated nor is the attic. Would love to heat common space with RMH and then zone heat areas like the kids' room with space heaters.

Any brilliant ideas come to mind?

I have a similar dilemma. I think it is doable; but you're probably going to have to make a "pocket rocket" and then vent the exhaust through the fireplace. to combat the heat of a pocket rocket you can put it up on blocks and then cover the tile with slabs of rock. That way its reversible. and if you cover it with alum. foil or another reflective foil it will push the heat upwards.

The pictures attached show what I did. I removed the fireplace and discovered it was going to burn the house down; and I plan on building a smaller RMH with mass about the size of the ledge that was there. I only have a few feet more of space, but think it will work out. Still gathering materials!

Suggestion for ya both. Maybe a small bench with a radiant masonry wall courtesy of Matt's pic

I think if you check out this link (which I borrowed from another thread here) (http://www.iwilltry.org/b/build-a-rocket-stove-for-home-heating/) You will find that you can just build a rocket without mass for instant gratification or if you think along these lines... the exhaust must be the same size or bigger than the fire box, tunnel, and rocket. It is better to have to much pull than not enough. If you have too much pull all you have to do (normally) is start covering the firebox until you have the right amount. Too little pull and you have to rebuild. If you look at a thread from 2010 about building an in-ground rocket for a Yurt you will see a great design that works. Just reduce you size from there. Also you might check out the portable Rocket stove on here. And most of all buy the book, which I am sure someone will provide a link for you. It's $15 for a .PDF version. I would be concerned about the heat coming from the barrel with two small children...

thanks chris, and martin for the suggestions; I'm not sure what I will go with here, but martin's suggestion seems tempting. I have some bricks and can make the chimney work I think. either way I'll post a full thread on whatever I end up doing. I hope the OP does like the thread he references with the old water heater and just pipes it into the fireplace; as he is renting and damaging the property would not be good.

Check this stove Rocket stove mini mass heater if it fits in your place.

If you use water, you could make the bench really short and still extract all the heat and then do a simple vent up the chimney.

However, the biggest problem will be finding a way to keep the water under 200F so as to not turn the water to steam, and cause a BOOM, due to high pressure.
How do we keep the temp under 200F, we could do a open container "bench".
We could do alot of short burns.
We could pump/dump/replace the bench water outside if it get to a "critial" temp of 180F.

We could look for other material other than water. that will turn to gas at a much higher temp like wax.
(or MERCURY, ok I am just kidding please dont try this)

Dj Radder? Did you get anywhere?

I think, i you can't knock the chimney down, you could make a sideways batch rocket. If you can get ahold of pozzolan chimney elements, you could make a rather nice one.

Check this thread. http://donkey32.proboards.com/index.cgi?board=experiment&action=display&thread=511 and look at my sketchup files, and also the one from Docbb on page 20.

Check the one by Rinchen here, quite good looking. http://donkey32.proboards.com/index.cgi?board=experiment&action=display&thread=474 Tho, i would have made a pozzolan element bell instead of the barrel.