several questions

i was discussing this with some friends online and several questions came up that i could not find answers to.

how do you regulate the temperature (just stop adding fuel)

are there any carcinogenic concerns? what are the level compared to a wood stove or fireplace?

does the mass have to be clay ? i like the bench idea but would like to build a box and fill it with something that is less permanent like sand or small rock. then put a bench seat and some cushions or whatever to make it look like a traditional corner seat.

my girlfriend wants to know does the barrel have to big this big ugly thing in the middle of my living room. I'm trying to find balance between performance and fashion.

Barrel wise, there is zilions of options. Only your imagination is the obstacle. There's a thread dedicated to this.

Hi Robert; I have only built one rmh, so i am no expert but... I'll try to give you some answers. Yes , if its to hot quit adding wood. The whole idea is to burn fast and hot , get the heat into the mass then let the fire go out. Cover your feed tube after it quits burning to hold your heat in the mass. Its awesome to find your mass still hot 12-20 hours later, and as long as there is still some heat, your next fire will be lit as fast as you can add paper and kindling. As with any wood fire if it gets smoky inside its probably not good for you, but a properly working rmh will draft so good that you should not have any problems. A working carbon monoxide detector as well as a fire detector is a really basic idea for anybody burning wood or coal or pellets in any kind of fire box. Next, as for the mass. Yes, you can use other things for your mass , but they will not hold the heat as long or as a good cobb and rock mass will, that will probably not be as much of a problem for you in Georgia as it is for us in the north country. One thing you can do is encase your mass with brick or after its cobbed or you can frame it in with wood (cedar is my choice) heck you could even sheet rock it. covering with a cushion is a common way to live with a rmh they make great day beds. Now your final question... The oil barrel in my living room!!! This is the biggest issue that most people have. As max said, there are many ways to deal with this. you can buy a stainless steel barrel (spendy) you can use a sheet of copper expanded metal and wrap around your barrel , you could stack brick ,with air gaps around it , You can cob the whole barrel , although that seems to be not recommended. Your imagination is the only limit ! In my mind if you have a wood stove , then you have a metal barrel or box in your living room already ! Hope this helps . Tom

You can use a brick or stobe "bell" You can also get from old farms or houses, some ols home heating fuel or tractor fuel tanks, which are square or rectangular, and you can dry stack bricks or pavers around. There's plenty of options.

Hello Robert and welcome to Permies!

how do you regulate temperature?
Mostly by the addition of wood/fuel to the RMH, you also have some control if you throttle/open the feed tube

Carcinogens?
You might get an occasional smoke back when starting or stopping the rocket mass heater. To avoid this I have been using a propane torch to preheat the J-tube, by the time I add the wood the entire system is already drafting. If you do not properly seal the ducting then you may have a leak. Cob will form a nice air tight seal over the ducting before leaving the house. In my case I have not completely sealed all the joints in the ducting and will have a leak or two. I will eventually seal them with masonry.
Once the heater riser is really hot it will burn most of the smoke/carcinogens (search Youtube user: broaudio, flue gas analysis of rocket mass heater)

Girlfriend - aesthetics?
This is entirely dependent on your girlfriend's tastes. I don't think I am even remotely skilled enough to assume what your girlfriend's taste preferences would be.

thank you all, for your responses, i feel more confident, now i just have to get the GF to go for it, wish me luck. i saw a barrel on line that was made of ceramic, if i understand the working of the RMH then this should be OK so long as the very top can handle the heat and its seals all around, correct? i also have some more reading to do to understand the dragon stoves and the differences. thank you all again.

barrel on line that was made of ceramic

Chimney flue liners (which are a fired clay) will crack if their temperature is raised by more than 50°F per hour. This would certainly be the case for a barrel over a heat riser. Consequently, although the ceramic could handle the heat if it were added gradually, I don't think that a ceramic barrel would work. Wouldn't it be fairly expensive also?

I would also recommend not using a ceramic barrel. The firebricks are special ceramics pressed and fired in a certain way to take the incredible strain of heating and cooling rapidly.

hey all, well i got some serious stink eye from the mrs. and technically she owns the place so, the rmh never happened. SO, how do i build a temporary setup, i live in GA, and it bottoms out to maybe 0 deg at the very worst late at night, extremely rare!  and honestly after 9 am when big red has been up for a few doing her thing (sun not GF) its already 40 and heck I have spent many winters in wife beaters.  so some kinda mini pocket rocket ish that i can retro fit to the existing hearth without modifying it and the living room.  any suggestions?  pictures and schematics are good for me.  thanks again, just planning for the winter that is coming up.

Robert;  Think about a Russian masonry stove & also look at how the dragon is built . A smaller brick bell system would have a small footprint , look good (if you like brick) heat quicker than a traditional masonry or a full bench rmh. And no 55 gallon barrel in HER living room.  It would also cool quicker than a full rmh.  Your floor needs to be strong enough and if its wood it needs protection as well.  You would not get that wood heat feel without a barrel... but a warm brick bell would feel good on a zero degree night. ( I didn't know Georgia went down that low)