Lets put together a masonry heater bill of materials

[KeithO]

I thought that a new thread may be needed to discuss a bill of materials for a masonry heater.

I have started to put together a list below which will need to be filled out to make it complete. For the moment, I am assuming that both the core and facing will be soapstone slabs, 700x300x60mm thick. Smaller pieces could be cut out of these slabs as required. Larger slabs 1000x300x60 are available if it fits the assembly better.

By using soapstone, there is no need for intricate mortar work and the slabs can be fastened together with splines and dowels instead. Grooves to accept the splines and gasketing can be cut in the edges of the slabs with a router equipped with carbide cutters. Holes that must be drilled can be done with a drill press and either carbide drills or a regular drilling machine. Drilling fixtures that have drill bushings welded to a support can be used to place drilled holes in exactly repeatable positions with perfect reliability.

I have yet to see how exactly the pieces are designed to allow for fastening together, but examination of the Finish heaters will reveal how this is done. Every masonry heater needs a min 12" reinforced concrete foundation and most of the soapstone heaters use a 6" or 8" class A stainless steel chimney. The super ultra customized units have the heated benches etc, but I am not considering this level of complexity.

Any contributions or alternative proposals will be appreciated. The first omission that comes to mind is a UL listed chimney connector.
Keith

 

[stoveguy2esw]

hmmmmmmm!! interesting concept , a soapstone masonary heater. i do not know a lot at all about soapstone , so i gotta ask how involved is it to work with soapstone (shaving out connecting bisquets etc to mate the slabs)?

 

[stoveguy2esw]

maybe frame it out with steel and bolt in the soapstone slabs? also , how much displacement does soapstone go through in a heating /cooling cycle? every substance must expand when heated and contract when it cools, question is how much does it? and if so how do you account for it ?

bear in mind that im very much soapstone stupid , but i do understand principles of manufacturing/ operation very well for stoves in general

 

[rhetoric]

Hey, KeithO, this is off-topic, but I lived in Spring Arbor for awhile and I don't ever remember being able to see that Mountain in your little photo there.

 

[tutu_sue]

I once saw a photo on the tulikivi web site of the pre-assembly stove. The interior components that made up the fire box and smoke channels were cut from solid soapstone. I couldn't tell exactly from the picture, but they appeared to be 4+ inches thick. After assembly on site, the heater is then covered with soapstone tiles using mortar.

There's a good reference for building masonry heaters ASTM E 1602. Tell you all the poop you need to know to be safe and there is a diagram of the Finnish contraflow heater design. Hey, I never knew it has to weigh as least 1,760 lbs. to be a masonry heater.

 

[KeithO]

I haven't kept track of this topic for a while...

Mike: The soapstone slabs are generally pinned. They go together almost Lego style. You can carve soapstone with carbide tipped blades in your router. They will wear out faster but one doesn't need diamond bits like most other rock.

Rhetoric: Good observation. Its my favorite place in Colorado, which is where I'm intending to move according to my 5 year plan. High, dry (the air, that is), sunshine and a distinct lack of people. And the mountains on the horizon on 2 sides..... Almost heaven.

 

[KeithO]

Sue, Nice treehouse. I'm jealous....

Its not uncommon on the core of the heater to use 2" slabs doubled up, both to add the needed mass and also to provide some security since both layers would have to crack to enable a leak path to exist. The heater core is highly stressed in operation but Soapstone has been anealed and "weathered" so as to be virtually stress free in its natural state. The lack of all those mortar lines also helps with durability. The "masonry" heaters will have double layers of firebrick inside in the hottest areas for the same reasons. The top layers which are the coolest will finally go to single layer (excluding the facing).