A wood-burning masonry cookstove

April 26th, 2014. Post by Quinta do Vale

Ach! Where does the time go? I’m so hopelessly behind with blog posts and there are now so many pending I scarcely know where to start. I just checked the last post I made about the outdoor kitchen for the wee house and it was a year ago!

Alongside the cob bread/pizza oven I built last spring (and which is now producing fabulous food), I also constructed a wood-burning masonry cookstove. I found an open source Sketchup model online and adapted it for Portuguese fire brick dimensions.

Sketchup model for wood burning cook stove

This is the adapted model. Click on the image to download the Sketchup file and open in Sketchup (3D modelling software which is free to download). Firebricks are colour-coded for different lengths. You’ll need to be reasonably proficient with an angle grinder (at the least) to build this stove.

Here is how the stove was built …

Wood-burning masonry cookstove for an outdoor kitchen

The firebricks were mortared with a thin layer of fireclay and fine sand. As with the cob oven, I set the firebrick base into a clay/sand mortar on a bed of levelled sand. Since there is an air channel running beneath the firebox of this stove into the back of the firebox and on into the chimney, there’s no need to insulate beneath the base of the stove.

Wood-burning masonry cookstove for an outdoor kitchen

Wood-burning masonry cookstove for an outdoor kitchen

I particularly like the design of this stove for the way it channels the combustion gases from the firebox forwards and up, then forces them into a laminar flow beneath the cooking surface back towards the chimney. This makes for a nice gradation of temperature from a good fast boil over the firebox to a rolling simmer at the back.

Some of the cuts in the firebrick were a bit tricky to do freehand, but inaccuracies were compensated for with the fireclay mortar when the stove was put together. A jig would improve matters no end. Or a chopsaw …

Wood-burning masonry cookstove for an outdoor kitchen

To keep the fire efficient, a mix of sawdust and clay slip was used (just as in the cob oven) for insulation on either side.

Wood-burning masonry cookstove for an outdoor kitchen

On the left side of the stove, I left a gap in the insulation so heat can transfer through a clay/sand mix into a circular chamber created in the work surface. This will be used as an insulated ‘hay box’ for slow-cooking soups and stews and will save on firewood for long cooking times. It can also be used for dishes brought to the boil on a solar cooker in summer.

Wood-burning masonry cookstove for an outdoor kitchen

Wood-burning masonry cookstove for an outdoor kitchen

I started off with a ceramic tile for a cook top. I was given a couple of floor tile seconds by one of the local builders merchants. I figured that the firing temperatures of these tiles meant they ought to withstand the cooking temperatures of a wood fire and it was worth a try since they didn’t cost anything.

What I’d failed to think about, of course, is the low thermal conductivity of clay and sand. This means that the heat from the fire is slow to spread through the rest of the tile, particularly the edges resting on the firebrick, and the stresses set up in the tile from the extreme temperature variations are too much for it to stay in one piece. The first tile broke in short order. The second one I tried using a thick bead of high temperature silicone to support just the very edges of the tile and allow combustion gases to get into the gap between the tile and the firebricks. It wasn’t enough. This was the result.

Wood-burning masonry cookstove for an outdoor kitchen

I found the cast iron doors for the stove on eBay. They were almost exactly the right size. Some further work with the angle grinder was needed to get them to fit, particularly to the bricks across the top front of the stove, so for added stability we drilled into these and used lengths of rebar as ‘dowels’ to hold them together.

I later discovered that the fire doors are widely available in Poland, where they’re manufactured.

Wood-burning masonry cookstove for an outdoor kitchen

Wood-burning masonry cookstove for an outdoor kitchen

Finally, the completed cooking area of the wee house outdoor kitchen! A 100mm stainless steel flue pipe takes the flue gases from the stove out behind the roof.

Wood-burning masonry cookstove for an outdoor kitchen

And the stove in use. I’m very pleased with its performance: it draws well, comes up to temperature rapidly, keeps a good steady heat and cooks well.

Wood-burning masonry cookstove for an outdoor kitchen

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5 Responses to “A wood-burning masonry cookstove”

  1. Frank Antonson Says:

    You do SUCH good work! Thanks for the detailed step-by-step sharing.

    Frank

  2. Indi Says:

    This looks excellent! Thanks for the ideas : )

  3. Song Weaver Says:

    WOW! This is GORGEOUS!!!! Great Work!

  4. Lonzo Says:

    Where di you get your current cooktop? Did you make it out of tile as well or did you fins a cast iron cooktop from an old stove? Great work by the way!!!!

  5. Quinta do Vale Says:

    Thanks. The tiles didn’t work. The cook top is cast iron. I found it online and was able to get the right size for the stove.

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