Peter van den Berg wrote:I copied the principle of a metal shell with the mass on the inside from the pönttöuuni, Finnish for "pot stove". A fairly common and relatively cheap solution to build a (small) mass stove. Unfortunately, the manufacturers of those rolled and folded parts are all in Finland and as far as I know they do not export because the stuff is very thin (0.7 mm) (0,00276"), has an awkward shape and is therefore also vulnerable.
If you don't look too closely, they actually look like a classic Swedish tile stove, the kakelugn. Only without tiles but with a kind of luxury oil drum around the mass. Internally they are actually quite conservative things, the combustion quality is actually only moderate in my opinion. But they have developed special materials for this type of stove.
What I'm going to try is to produce a flatpack, much like Ikea, from that octagonal biscuit tin, the concrete bricks can be purchased locally. As you can see in the first picture, there is a steel container inside that can hold the Shorty core. I wanted to assemble that core from ceramic oven plates, with insulation around it so that there are no problems with expansion. Since the core spews the hottest gases forward instead of upward, only a limited number of firebricks are needed directly above the firebox to protect it. The top does not have to handle high temperatures so there is no need to apply stone-like material there (I hope). In addition, a simple stove fan can remove the heat produced at the top. Most of the work will be in the specific parts of the door and air supply.
There are no channels in the thing, only mass along the perimeter, which makes stacking or laying bricks relatively easy. The total mass is in the order of magnitude of about 800 kg (1760 lbs). I also drew another version, which is wider, about 1 meter (3.28'), it can hold a larger core and the weight of that comes to about 1200 kg (2650 lbs). The finish can be anything, from rolling with black fireproof paint (works quite well!) to a RAL color powder coating of choice.
If it doesn't work out, I'll have used up my budget for a year and have been happy experimenting, right?
Hi Peter,
In book Finnish Fireplaces: Heart of the Home by Heikki Hyytiänen, Albie Barden, and Aila Rapeli.
available for free, see link below, at page 17 you can see the temperatures in a Finnish ponttouunit.
https://drive.google.com/file/d/1jGVxeSpZ0cm8-C-gnfpV7iBal8aMiR7M/view?usp=sharing
What is your opinion regarding the combustion temperatures?
Seems to be higher than in a classic Swedish tile stove, the kakelugn.
Please consider also to view this video
https://www.youtube.com/watch?v=znVxrKN0XVs
Poêle de masse rond en kit avec finition émaillée - Construction étape par étape du modèle Aïda
