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Small cracks in vent

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  • Small cracks in vent

    My vent area leaked smoke in 3-4 places on my first outdoor mailbox
    oven. I just let it fully dry out, then covered it with a second
    layer of refractory mortar. Then, as Jeff says, I made sure the whole
    assembly was smoke-tight before I moved on to insulation and my
    finish walls.

    Has anyone ever pointed their infrared thermometer at the vent
    masonry when the oven it hot (I don't have a gun here). If the oven
    floor is 700F +/-, how hot is the vent right about the oven opening?


    >The cracks are no doubt due to expansion and will expand and contract with
    >each firing.
    >As long as they are only hairline, no need to repair. Since they almost
    >disappear when
    >the cladding returns to room temperature. As long as the inside bricks have
    >been properly
    >mortared you shouldn't have any leaks that will be a cause for concern.
    >If you see smoke coming out the cracks, this may actually be water from the
    >concrete or
    >mortar being vaporized because of the heat. This may have added to the cause
    >of the cracks
    >in the first place.
    >Have several more firing before you insulate and close in the dome. Monitor
    >the cracks to see
    >if the continue to grow in width.
    >We lit our first fire and found a tiny hairline crack on the
    >claddign around the oven. Should I fix it? How, with Concrete or
    >something more flexible?
    >Aesthetic question...
    >The bricks I got have cores in them which is fine for stacking but I
    >am not sure how to finish of the top so that teh holes don't show.
    >On the chimney, I will likely stand the last row on end but what
    >about the front facade that doesn't go as high? Any suggestions?