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Old stone house france, can a RMH heat it all up???

sophie rey

Joined: Oct 26, 2012
Posts: 2

I am restoring an old stone house - 3 ft thick walls, with 40 square metres open plan ground floor,2.6m high, and the same floor surface open plan upstairs, 4 m high. Heating needed 4 months/year.

I'd really like to make a RMH , I love the enthusiasm and examples on this site, but am wondering if it is appropriate - will it heat all the space

It is in southern france where we all use wood burners with stacks. However this building doesn't have an existing chimney so all options are open. Even basic ecological building methods , or getting serious about insulation etc meets much scepticism, However the houses are freezing in winter! So the idea of a chimney free stove is going be ridiculed and I want to be sure the full space downstairs as well as the upstairs will heat up.

I'd welcome any thoughts and suggestions

Thankyou very much


Satamax Antone

Joined: Sep 24, 2011
Posts: 1589
Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
Salut Sophie, tu est d'ou?

Well, i'll carry on in english, better for other readers hey!

Sophie, i've tried the side of the house exhaust, no good, you'll need a proper chimney. 40sqm, about 400 sqft, no bother to heat that up with a rocket. If you have bedroms above tho, i don't know I'm a beginer in rocket stoves. Having made only two, and on my way to build a horizontal batch rocket. i like the idea of having a kind of fireplace effect.



God of procrastination Sad for sir Terry! 28 April 1948 – 12 March 2015
Galen Johnson

Joined: Mar 01, 2010
Posts: 24
I am sorry, but you will never get the house warm, not with uninsulated, three-feet-thick stone walls, with their thermal mass and momentum. You could put a blast furnace in it, but the second you turned off the heat, it will go back to being frigid again. You can aim for a warm room, maybe, at best, but you will have to enclose it from the rest of the house.

These types of houses were not built to keep the cold out, they were built to keep the wind out.

No radiant heater will work beyond ten feet, twelve feet maximum, no matter the type, rocket mass heater or Russian Masonry or cast iron. I don't understand that the house doesn't have a chimney, does it have a thatched roof that lets the smoke filter out? Only very old, medieval houses had no chimneys -- or else houses far out in the country.

Unlimited growth: the ideology of capitalism and cancer cells.
sophie rey

Joined: Oct 26, 2012
Posts: 2
dear max and galen

thanks very much for your replies.

Well, houses here do heat up (20 celsius say is good) despite having usually merely plaster and hardly any roof insulation/well glazed windows etc.
I have put on 8 cm of hemp and lime render. And well insulated roof/double glazed windows so I should be able to get snug ( i'd prefer 22 degrees) if i choose the appropriate stove/method.
The houses take about three weeks of good steady heating to warm up, then as long as you heat every day they'll be ok til the spring. But if not heated for about 4 days they fall back to cold again.

If I understand well you suggest a RMH wont heat a 40 square metre room? thats a pity.

max I live in the vallee de l'orb, a little north of beziers, southwest france.

galen, The house/building 's foundations are 1100. then allsorts of variations - extensions/reductions since then. So it isnt clear if a chimney got absorbed into the adjoining building or if my building's purpose was never residential, or the bit of it that stands today.


Galen Johnson

Joined: Mar 01, 2010
Posts: 24

Well, if it heats up, it does. As far as the number of radiant heaters you need, that depends on how the room is styled. A forty-square-meter room that is square can get by with one heater in the dead center of the room, since the room would be a little over 6 X 6 meters, and six meters is the maximum distance a radiant heater will heat. If the room is rectangular, it will require a heater six meters from each end, and spaced twelve meters or so from each other, as near the centerline of the room as possible. Two sound sufficient.

Chimneys are required. A fire in an enclosed room will suffocate you in the dead of the night with carbon monoxide and carbon dioxide.

As to the size of the things, just make them big ones. A toy won't work. RMH's require smaller logs, sticks really, and you do have to feed them. Russian masonry heaters are something you should look into, since it sounds like their slow-release of heat is what you are looking for.
Charlotte Amelia

Joined: Nov 17, 2012
Posts: 1
Hi Sophie,
I have got a house in London UK built into a slope so it is partly underground downstairs, which is similar to your situation with the thick stone walls.
I have got a Morso Badger secondary burning convector stove with a baffle, that burns off its own smoke, in the middle of the house and at one end of the lounge. It generates hot air currents. the metal chimney is insulated and no soot builds up inside it, and it saved me having to build a masonry chimney. The chimney heats the bedroom above, that it goes through.
It gives out the equivalent of two electric fan heaters or 6 units of something=btw's? whatever the standard measurement is. It has been in 2 or 3 years and is just enough in a very harsh winter for an insulated house. As I am relying on the chimney itself to heat the inside of the house and a rocket mass heater keeps the gases inside the house a long time before they go outside, it probably would be enough on its own. I want one as well it looks loads better than what I have now. The expert , Ernie said he was burning an eighth as much wood as before, but he may not have had the secondary burning type of stove with the baffle to re-ignite the smoke particles.

It would work like a storage heater keeping the heat in its mass and releasing it slowly over a long period of time, that is the man advantage, allowing the heat to percolate into all the small spaces around the house. I have heard that masonry chimneys do that too.
Adam Poddepie

Joined: Nov 11, 2012
Posts: 68
Let's say 1 heater wasn't enough, would it be crazy to just put 2 in? it seems like it would be more comfortable overall. Perhaps she could construct it so that the combustion chambers were side by side for easy use, but the themal mass portions were parallel-ish? Then she could fire one up, and if it proves to really not be enough for the winter she could fire the second one up too? Just a thought. Plus it could turn out to be some really cool seating, like a box shaped bench (hollow square) with a table in the middle!
Ernie Wisner

Joined: Oct 16, 2009
Posts: 789
Location: Tonasket washington
two would work ok. not a crazy idea at all.
yes stone houses do heat up and yes an 8" rocket stove will heat it, it just takes a bit of time to heat the walls. if the house has a good plaster on it its going to be fine. as for the poke the pipe out the wall idea unless you have a wind that only blows from one direction it would be better to go out the roof or someplace high in the gable wall then up above the ridge beam.

Need more info?
Ernie and Erica
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