This is one of our SR-18 fireboxes with 10 years of use burned on a daily basis for 5-6 months a year during the winter in Duluth MN. Still looks like new.
Side view of firebox
Rear wall of firebox and channeled throat going around the white oven. There is a little bit of fly ash on the side walls that could be brushed off but after 10 yrs of use on a daily basis in the harsh Northern MN winters it is in great condition and will serve the owners for another 10-20+? years before needing maintenance. This is why masonry heaters are such a great investment. They have a high up front cost to them but they will need little maintenance on a yearly basis and will last for 100’s of years with proper use.
This is a photo of the rear wall of the heater above the firebox. The channel or hole that you see is going on the back side of the white bake oven. The piece of cast refractory you see next to the channel is the bottom of the white oven. This is one of our older designed white ovens and this one has a piece of cast refractory for the oven floor. You can see a small hairline crack in this casting. This has not effected the performance of the white oven, nor the integrity of the slab. The owners say that they get little to now smoke on the inside of the oven, and if any smoke it is very minimal and only a few times a year.