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Post by belgiangulch on Nov 27, 2018 8:18:08 GMT -8
Hi all; Finally working on my shop stove. 8" J tube with 55 gal barrel then brick bell. As is usual for my questionable methods, other than a general idea of what I want , I worry / think about each step only when I reach it. I have reached a point where its time to come up with a solid plan for the exhaust path. I'm curious how a brick plunger would work. As brick columns are a benefit (within reason) in a bell. I was thinking a brick plunger in a corner, might be a worthwhile method. Has this been done ? Are there specs or photo's ? Is this a valid idea or a dumb xxx idea? My other thoughts on exhaust venting are, bringing regular stove pipe thru the bell roof and down to a trumpet near the floor ? Or bring the exhaust pipe down the outside of the bell either to a 90 going thru the wall or maybe a small brick box sticking out past the wall with my flue pipe dropped straight in ? Suggestions, criticisms, ha ha praise ?
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Post by peterberg on Nov 27, 2018 8:36:21 GMT -8
It has been done in brick, inside a bell. In fact, building this in a corner doesn't reduce the ISA, it's reducing the volume but increasing the mass. There's one very important proviso: the exhaust opening leading into that plunger stack need to be huge, let's call it 200% of system size as a minimum. The coldest gases in the system need to stream up there and rounding a 90º corner at the same time. Too small an opening and the whole system becomes sluggy or it would easily pick up a pulse because of this restriction.
I did it two times with an insulated tube, hanging twice the system diameter from the floor and both worked fantastic.
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Post by coastalrocketeer on Nov 27, 2018 10:42:13 GMT -8
A brick column could also include slots for a simple metal plate in an opening near rhe top of rhe bell for a bypass to assist draft and warming the chimney at startup... Slots at top and bottom of opening, and full height slot would extend through the outer wall of the bell to a handle or other mechanism of operation.
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Post by belgiangulch on Nov 27, 2018 10:45:41 GMT -8
Hi Peter; Thank you for the quick response! If I understand correctly, a brick plunger in a corner has been done but needs a large opening. How would a person accomplish that ? With a sheet metal shield extending out into the bell just over the floor ? Is there a posting with pictures ?
The second part of your post you mention insulated pipe. I assume that is pipe dropping down thru the roof of the bell ? I like this idea as well. Could be much easier to accomplish than a brick plunger with a deflector.
What are your thoughts about leaving the pipe exposed outside of the bell? Putting a 90 thru the bell wall ? Or a brick box allowing the pipe to drop straight down onto it ?
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Post by coastalrocketeer on Nov 27, 2018 10:53:46 GMT -8
The "mass heat storage" benefit of making the chimney of brick will be less than for the same amount of brick as a free standing column inside the bell. Heat will be lost on the sides of any bricks to the internal chimney facing side, and any sides of that chimney brick that are part of the side wall of the bell will never be heated past your exhaust temps.
Having your exhaust column not against an putside wall woukd prevent this lack of heating of that portion of the bell walls.
A CSA metal pipe, with insulation around it, then a brick column around that, and with oversized opening down low would give you more bang for your buck on heat storage for bricks used inside the bell.
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Post by belgiangulch on Nov 27, 2018 10:55:00 GMT -8
I do have an untried plan about preheating my chimney(I hope I won't need to). Especially if it is exposed running up the outside of the bell. My Plan) This is an auto shop, there is an ox/acx. cutting torch nearby. If I have a need to preheat the flue, it should take a minute or so running that up and down the exposed pipe and the heat should be rising ... I'm thinking/hoping that will do the trick.
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Post by belgiangulch on Nov 27, 2018 11:10:11 GMT -8
I like the idea of an insulated pipe dropping down with a brick column around it. When you say an over sized opening down low what did you have in mind ? I'm having trouble visualizing it.
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Post by satamax on Nov 27, 2018 11:56:37 GMT -8
Belgiangulch, I don't know your system size, but let say, you have an eight inch pipe. You fit a 10 inch to 8 inch reduction at the bottom end. And you are sorted. And hold all the pipes and reduction with rivets. So it's self hanging. Wrap with rockwool and chicken wire.
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Post by peterberg on Nov 27, 2018 12:04:53 GMT -8
If I understand correctly, a brick plunger in a corner has been done but needs a large opening. How would a person accomplish that ? With a sheet metal shield extending out into the bell just over the floor ? Is there a posting with pictures? The brick internal upstream channel should be in a running bond with the bell's wall. The corner that is hanging above the floor could be supported by a steel stud or something along that line. A box extending from the bell's lower courses is close to ideal for an external steel exhaust pipe. The exhaust box could be plenty wide while the stove pipe can get into it straight from the top. Look at the Mallorca build, that one is done that way.
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kpl
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Post by kpl on Nov 28, 2018 0:52:22 GMT -8
I like the idea of an insulated pipe dropping down with a brick column around it. When you say an over sized opening down low what did you have in mind ? I'm having trouble visualizing it. Does that pipe actually have to be insulated? Uninsulated pipe would, certainly, steal some amount of heat; but it would heat up the chimney gases, which should eliminate the need of damper! When starting up a cold heater, chimney pipe would get hot quite quickly at the top, encouraging gas flow. That way, lower part should heat up quicker. I'm in similar situation with my workshop heater: it's a rented place that I do not want to invest a lot; There is only a hole in a wall that I have installed single wall tin chimney through, and there is very little space for a heater itself. Additionally, there is a need for both quick heat and for heat storage, to avoid workshop cooling completely until next evening, as there may be some paint/varnish/glue drying in the room.
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Post by satamax on Nov 28, 2018 3:49:54 GMT -8
Kpl, i believe it is necessary to insulate.
Otherwise, you're robing top much heat from the Bell.
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kpl
New Member
Posts: 47
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Post by kpl on Nov 28, 2018 5:08:30 GMT -8
I should try that. In my opinion, this must level itself at some point. As gases in chimney move faster, they have less time to rob heat from chimney walls.
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Post by belgiangulch on Nov 28, 2018 8:32:46 GMT -8
I'm now leaning towards an external chimney. Building in a brick exit box that my flue pipe can come straight down too outside the skin of the bell. Similar to what "Dragon Heaters" has done on their masonry build.
I have been offered enough 10" pipe sections to reach my roof jack ,for free. I'm wondering if I can use a 10" flue with an 8" J ?
I should add more info here. My class A thru the roof (1 section ) is 6"... my thoughts here are to use the 10" for 14' then reduce to 8"for one section and reduce once more to enter the 6" class A
My plan all along was to run 8" all the way up and try switching 6" at the last. I am well aware this may not work, as there are no codes to worry about out here if this reduction is a problem I will remove the 6" class A and replace it with 8"
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Post by coastalrocketeer on Nov 28, 2018 8:51:23 GMT -8
Kpl, i believe it is necessary to insulate. Otherwise, you're robing top much heat from the Bell. This just gave me an idea... one could insulate all but the top inch or two of a single wall pipe, and find a good medium that provides the function of a bypass by creating enough heat transfer to induce draft early in the burn, but not so much that overall efficiency is badly affected.
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Post by satamax on Nov 28, 2018 9:06:04 GMT -8
Kpl, i believe it is necessary to insulate. Otherwise, you're robing top much heat from the Bell. This just gave me an idea... one could insulate all but the top inch or two of a single wall pipe, and find a good medium that provides the function of a bypass by creating enough heat transfer to induce draft early in the burn, but not so much that overall efficiency is badly affected. Thought about this, this morning too.
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