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Post by waynem11 on Nov 30, 2011 7:36:12 GMT -8
My stack exits 7 feet up the wall. It goes through a 24 inch stove pipe to a Tee with a Vacu-stack. When the stove is not in operation the inside stack gets pretty cold. I'm thinking a damper near the wall exit could prevent cold air from entering when the stove is not running. Any thoughts on this?
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Post by rectifier on Dec 3, 2011 16:05:34 GMT -8
Yep, I used to live in a house with a setup like that. Prevents downdraft from getting established in the stack.
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Post by waynem11 on Dec 9, 2011 13:16:42 GMT -8
Thanks, I have one on order. Meanwhile I use a grabage bag over the Vacu-stack. I take the bag off before lighting a fire, but I'm having real problem with smoke backing up. I have a cleanout at the base of the stack and put lighted newspaper inside, seal, then a wad of newspaper in burn tube then light the kindling. It usually starts off fine and burns pretty good for a few minutes, then it slows down and starts smoking back into house. I've put a fan over the feed tube and this gets it going in the right direction, it may burn okay for awhile but then starts back drafting. One time it was blowing heat out the feed tube at a scary speed. I'm not sure what is causing this. My first guess is the cold air outside is just over powering the exit gasses. My system is new with freshly added cob and one flue pipe is one third exposed. I have 15 feet of horizontal flue tube and 7 feet of verticle stack then a 2 foot horizontal that exits the wall to a Tee on which is mounted a Vacu-stack. This is on the gable side of the house. Would extending the stack/chimney another 10 feet to clear the roof do any good? Seems to me just more cold pipe for the warm air to overcome. I am wondering if the heat riser is getting hot enough to push the gasses. I don't hear any rocket noise from the barrel, although I get a nice roar from the feed tube when it first starts working. Any comments would be very welcome.
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Post by canyon on Dec 10, 2011 1:14:00 GMT -8
I am building a "guillitine" style damper for an 8 " system right now. Currently the owners are plugging the system manually in between fires with a wad of fabric at the primer hole tee at the base of the exit stack. They have seen significant savings in heat by their efforts. This is a subject of debate for some people as there is potential there to back up gasses into the living space (CO of particular concern) if the damper is closed too early or left closed when starting a fire. There are laws in places that require a certain percentage of the damper to be open space to try and prevent this backup. So, be aware. When I hear of a rocket that has backflow problems I first off investigate the draft situation. Usually, it is blockage (for example, wet wood was burned and clogged the thing). That helping hint thread about the transition zone from barrel to ash pit sure shines some light onto this subject.  |
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Post by waynem11 on Dec 10, 2011 19:53:28 GMT -8
How does burning wet wood clog a system?
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Post by canyon on Dec 11, 2011 12:44:22 GMT -8
Burning wet wood clogs the system by not really burning completely, slowing the system down and sending lots of stuff downstream to condense and build up eventually corking off the flow. I have even seen it clog the space at the top of the heat riser (gap between the barrel top/heat riser). This was discovered by checking draft with a burning stogie at first the primer hole then the ash pit clean out and deducing that the cloggage was between the ash pit and the burn feed. Then upon probing I felt the cloggage and knocked it out all around and restored draft. Another time (on another stove) it was in elbows at the end of the bench runs. I knew about non dry wood issues from theory but have now had the real knowledge of experience on my stove and also with others that I have built. People (myself included) think oh, I can just get it hot and cheat a little with some not so dry wood but the truth is that there is a cost. |
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