Hi Cindy,
I took a look at your dragonheaters.com website. Those are interesting designs and systems. One thing that I do like about the RMH is that the metal drum does give you that immediate heat response, but I also like the idea of a system that can be burned less often and can store a larger percentage of the heat in a mass buffering system.
Hi Mike,
The $3K - $4K estimate comes from two sources. The first being a design manual for a Finnish masonry heater from MaineWoodHeat.com (
https://mainewoodheat.com/shop-maine-wood-heat/publications-manuals/the-finnish-fireplace-construction-manual-%C2%A91984-with-a-2006-update/ ). Its part list comes to $3K 20 years ago and I can only imagine that it is at least $4K now. The second was from a blog about a guy who built a masonry heater and the materials cost him $3K. Both are flue type masonry heaters.
I read "Masonry Heaters" by Ken Matesz a few years back. I can't remember if his designs were more flue or bell based. At the time I liked the idea of designing my own heater, but I've since grown towards the idea of building a tested design which is why I got the Finnish Fireplace manual.
Did you design this heater yourself or are you working from an existing design? Do you have links for the masonry heater Peter Van Den Berg's firebox? I googled him and found links for a number of stoves, especially rocket stoves. I need to look back at the Matesz book, but do you have any preferred resources for bell masonry heater designs? Also, what size space is your heater going to be heating? I am looking to heat about 1500 sq ft.
If you are using homemade adobes for the outside walls/thermal mass, is there much benefit of this system to a RMH as they will have a similar thermal delay in the mass storage due to the cob/adobe's fairly low thermal responsiveness? If I build a masonry heater I would lean towards refractory materials for the core and brick for the exterior and mass. Brick isn't as responsive as stone and especially soapstone, but it is a fair bit more responsive than adobe/cob (if I am remembering right). Do you feel that homemade adobe bricks will hold up to the thermal stresses of a masonry heater? Also what is a CEB?