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Water and Snow in thru Chimney - Forno Bravo Forum: The Wood-Fired Oven Community

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Water and Snow in thru Chimney

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  • Water and Snow in thru Chimney

    Hi guys. Have a question for you. I have not used my oven for a few weeks and went out to check on it.

    I noticed some water on the oven door. Not a lot but you can tell it had dripped on there because some of the black soot from the chimney was stained on the door. We're now into snow and the other day I noticed some snow on it.

    My guess is it's blowing in thru the chimney cap. I have a plat steel cover on the front of the entire entrance so I do not think it's blowing in at that level.

    I posted the pic.

    Little concerned because if it seems thru the firebrick, the thermal foam insulation below would get wet.

    Thx
    Attached Files
    Check out my build at:
    http://www.fornobravo.com/forum/f8/t...uild-4678.html

  • #2
    Re: Water and Snow in thru Chimney

    I think you are right in being concerned. My answer might not be aesthetically pleasing but I would suggest removing the spark arrestor cap and replacing with a cover that would exclude the rain and snow. That is what I do; I use an inverted S.S. mixing bowl. This would mean that you would have to get out the step ladder and replace the spark arrestor the next time you use the oven. And then removing the cap and replacing with the bowl after the oven has cooled.

    Maybe not the easiest solution but better than seeing a post next spring wondering what one does when one has had water intrusion over the winter with subsequent freezing in the insulation resulting in damage to the structure. Or if no physical damage, having to wait for the oven to dry out before using it.
    Wiley

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    • #3
      Re: Water and Snow in thru Chimney

      I was thinking of putting a piece of metal, slightly concaved, that extends from the top of the door to the bottom of the entry. Anything that enters from the chimney would be directed out of the oven. Seems like a simple and effective solution. Still have to work out the details of the flue mess.

      Les...
      Check out my pictures here:
      http://www.fornobravo.com/forum/f8/les-build-4207.html

      If at first you don't succeed... Skydiving isn't for you.

      Comment


      • #4
        Re: Water and Snow in thru Chimney

        As an experiment, to confirm the snow is making it in at the top of the flue, put a garbage bag over the top to seal the snow out. If the problem goes away, you have identified the part that "need's fix'in".

        The down side is that it will look pretty bad... but if you can confirm snow is drifting in, you can work to modify the spark arrestor to keep the snow out...


        JED

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        • #5
          Re: Water and Snow in thru Chimney

          Have you seen the cool spring loaded chimney caps?

          there is a chain that goes down the flue and you can pull the cap down when the fireplace (or WFO) is not in use. Here's a link:

          ENERGY TOP Fireplace Dampers

          Christo
          My oven progress -
          http://www.fornobravo.com/forum/f8/c...cina-1227.html
          sigpic

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          • #6
            Re: Water and Snow in thru Chimney

            Seems a bit pricey - but a very clever idea!

            Les...
            Check out my pictures here:
            http://www.fornobravo.com/forum/f8/les-build-4207.html

            If at first you don't succeed... Skydiving isn't for you.

            Comment


            • #7
              Re: Water and Snow in thru Chimney

              Interesting chimney cap. Unfortunately upon reading their advertisement:

              Quote:
              NOTE: Top mount dampers cannot be installed on chimneys that vent a wood stove or gas logs.
              (end quote)

              So that definitely puts a damper on using them on a WFO (pun intended)

              I think it would be interesting to know the temperature of the exhaust gasses during fireup. I have a thermometer I could hold in the exhaust gas stream (standing on a step ladder) that should give feel for the temps. I am doing a Thanksgiving turkey and so I'll give it a test; although from what I've read one doesn't want as fully saturated WFO for roasting a turkey.

              Anyone ever measure the temperature of the exhaust gasses escaping the top of their WFO's chimney during fireup?

              Wiley

              Comment


              • #8
                Re: Water and Snow in thru Chimney

                Originally posted by Wiley View Post
                Anyone ever measure the temperature of the exhaust gasses escaping the top of their WFO's chimney during fireup?

                Wiley

                No, but I've wonderd about it... strikes me as being a valuable bit of information when trying to decide on the chimney cap type.
                "Building a Brick oven is the most fun anyone can have by themselves." (Terry Pratchett... slightly amended)

                http://www.fornobravo.com/forum/f8/p...pics-2610.html
                http://www.fornobravo.com/forum/f9/p...nues-2991.html

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                • #9
                  Re: Water and Snow in thru Chimney

                  Well it is definitely coming down via the chimney. I went and looked again and there is some snow just on top of the oven door. I put a piece of plastic down wrapping the oven entrance and then down along the floor of the entrance then put the door back in place. I figure when I check on it I can just pull the plastinc away and shake the snow out and put it back. I think as long as it keeps it off the bricks and I keep an eye on it so that spring thaw does not melt it and cause it to seep down into the insulation I should be OK.
                  Check out my build at:
                  http://www.fornobravo.com/forum/f8/t...uild-4678.html

                  Comment


                  • #10
                    Re: Water and Snow in thru Chimney

                    that cap wont work with gas logs or wood stove? sounds like fireplace wood burning only.....

                    Do you think a wfo is close enough?

                    christo
                    My oven progress -
                    http://www.fornobravo.com/forum/f8/c...cina-1227.html
                    sigpic

                    Comment


                    • #11
                      Re: Water and Snow in thru Chimney

                      Happy Thanksgiving Christo!

                      I think that perhaps they designed their cover/cap for chimneys with greater lengths than the short runs we have in most of our WFOs. Longer lengths giving more time for the gasses to cool. I'm all set to measure the temps I get in tomorrow's burn and while I won't be trying for a high heat burn I expect to get the flue gasses to burn clear and clean. The thermometer I have tops out at 900F so if it's more than that I'll have to figure something else out by which to measure the temperature.
                      Happy Eating,
                      Wiley

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                      • #12
                        Re: Water and Snow in thru Chimney

                        My chimney is open to the elements. The only problem is that any descending water washes soot onto my brick floor. This is an aesthetic issue only: but I've still been meaning to put up a flue cap.
                        My geodesic oven project: part 1, part 2

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                        • #13
                          Re: Water and Snow in thru Chimney

                          Awww Wiley.... No big scary fire today?

                          That will be some good data for us.

                          Christo
                          My oven progress -
                          http://www.fornobravo.com/forum/f8/c...cina-1227.html
                          sigpic

                          Comment


                          • #14
                            Re: Water and Snow in thru Chimney

                            Here's hoping that everyone's Thanksgiving went as well and was as enjoyable as ours.

                            I started my fire at 9:00. It was not a huge fire and by the time the oven had setted in to a nice clear exhaust the temperature of those gasses exiting the chimney measured 635F. That was measured at the top of a four ft. single wall SS chimney. I will measure the temps the next time I do pizza or have a raging fire as this fire was quite tame compared to my usual inferno.

                            The turkey (14.4 lbs) went in at 10:00 and was ready 3 1/2 hours later. I think I could have shortened that time by twenty minutes or so. The cover was left off during the first thirty minutes when the oven was the hottest. And I kept a small fire /bed of coals going throughout the cooking and rotated the roaster every half hour. It was very gratifying to see of the two turkeys served (I carved and both were served at the same time) mine was rapidly and almost completely consumed while the standard oven baked one was left untuched until mine was all but gone. Lots of nice comments about the mild smokey flavor. Here's a photo of the bird as it came out of the oven.

                            Also this was the first real test of my remade smoke door.The Hardibacker one finally broke into about a dozen pieces. Basically having reached a state of fragility that it could not withstand any handling at all. It was so broken as to make it difficult to use it as a pattern. The new one is made of 10 guage steel plate (1/8 inch for those not familiar with guage thickness).

                            The new smoke door works well and to my pleasant surprise is much better at controling the oven's panting. While the smoke back blasting out the front (to be immediately sucked back in) is diminished, the pant itself is louder and now there is small yet decernable puffing of smoke out the top of the chimney (in time with the pant). I will set up, record and make a posting of this panting as I find it quite cool.

                            Wiley
                            Attached Files

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