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My chimney/hood/stack setup


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Hello All, thought I would share the design I came up with for my chimney/hood/stack/forge setup.  Admins, wasn't sure to post it here or in the builds! This is primarily about my stack so... Please move if needed.

So I read through a bunch of the threads on here and built my setup based on what seemed to be the consensus (with materials I had on hand).  I was given a few 6'-ish pieces of 10" spiral duct and decided to build around those.  I built my forge at the same time using the water cooled side draft forge design and the hood is built from the "Super Sucker Side Draft" design.  I had a few issues with the tuyere being too close to, and too far below the face of the side draft so I made an adjustable setup where I can move the tuyere left and right (while standing from the side) and up and down to fine tune the hood (first pic shows the original setup, forth pic shows the modified setup). I can show more pics of that setup if anyone wants to see it.  It is limited to about 2"-4" of movement, but I don't see it moving again.  The forge was built from an old oil fuel tank I got from my neighbor.  The base was from a recycle heat treat oven.  I am using a blower that is in the base and piped out to the tuyere through the side.  I control my flow with a VFD (variable frequency drive).  I can come up to welding heat in about 5 minutes from the start of the fire. 

I didn't want to go through the roof of my workshop because I didn't want to try and deal with sealing a thimble with a steel corrugated roof.  And I really couldn't afford the thimble for a 10" duct anyway.  I couldn't find a wall thimble at 10" locally so I wanted to see if I could make my own with just store bought components.  I drew a cross section to show the idea I came up with.  This is primarily the reason for the post, to show a different way.  I am also about 8'-10' away from the fire so the heat at the "thimble" is not crazy hot but it is warm.  So take precaution, I am not accountable for anything that could go wrong with your setup!  I can forge for a long time and not have any issues with heat.  The vinyl siding on the outside is in direct contact with the 12"-10" reducer and I haven't seen any signs of melting or warping at all.  So figured I would show the setup.  Again, please be cautious and check temps regularly.  Every time I fire up the forge, I am checking the pass thru inside and outside. 

The side draft works great, it draws like crazy (once it gets warmed up) and I am super happy with the outcome.  I used firebricks I had from the recycled heat treat oven to take up the dead space so all of that is not coal!  (pic shows an early setup of bricks, I ended up making a pocket around the tuyere and then making a shelf about 2" from the top) Forgot to snap a pic of the final layout.  My water has antifreeze in it, that's why it looks rusty.  Will be painting it here in the summer and finishing up a few things, but all in all I am happy.  Hope this helps. 

Regards, Adam

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Edit:  I wish I could remove the above pic from the post as this was not the direction for the thread, but what "not" to do for future reference.

 

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I can't opine about how safe your coal chimney is, they don't usually get very hot but. . . 

What jumps out at me though is how hot it'll get if you get a creosote stack fire in the wood stove stack. 

I've never heard of a building code that allows two different fire appliances to share the same stack. I could be wrong of course. What does your: building codes, fire dept. and insurance carrier say?

Frosty The Lucky.

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That setup is temporary because I wasn't sure where I was going to place the fireplace.  This was to see if it is worth having the fireplace there or to even have a fireplace at all (I really need a lower ceiling for the wood burner to be effective).  I have since received some Mr. Heater infrared propane heaters I am setting up in its place (easier to move around in the shop if needed).  I highly doubt that this setup is close to code.  Ha.  It did however work well for the few fires I had in it this winter.  I ran the tee so I could add another forge in the future if I wanted too (want to build a bottom blast at some point just to have one).  That fireplace will soon be going into a sauna I am planning to build.  Thanks.

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It seems like it works well, but seriously, if you want it to stay up don't let a code officer or your insurance get a look at it... There are a few glaring items that would make it come down immediately.. I'm not an expert, but I just had a chimney put in (to code) and I learned a few things along the way. The first being that the process is a pain in the butt (with the town) and the last being that I sleep better knowing that it was put in properly and is safe.

I don't mean to rain on your parade, but be careful and practice common sense/fire safety. If anything happens (even if it's not related to the chimney) your insurance will not cover the damages and you will be stuck with the bill. There are many examples of this exact scenario. 

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As it stands; that looks like it was designed to collect creosote and have chimney fires.  If there was to be a structure fire; no matter what caused it, that set-up would give them an out to not pay off on the insurance.  Please remove the stove pipe and store it elsewhere till you are ready to move the stove out.

(40 years of smithing and I've made apprentice!  It's the Diplomatic corps for me!  old goon show reference...)

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As stated previously, this was temporary.  Good point to remove the stove pipe (in case something does go awry) and will look to get a plug and close off the side inlet by the pass through.  Appreciate everyone's concerns.  I don't want to lose my shop and would not have done this if I felt it unsafe as I am aware of the potential dangers.  I wish I could remove the pic from the post as this was not the direction for the thread, but alas, it is locked in for posterity and what "not" to do for future reference.  Again, thanks. 

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What did you expect when you posted here? Oos and aaws of admiration, or honest opinion? 

There's a saying about the internet and revealing things you wished you hadn't. "Say it forget it. Write it regret it." Posting on an international forum that does NOT delete anything isn't a good way to keep something quiet.

Frosty The Lucky.

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I've found that there is nothing quite so permanent as a "temporary" solution.   I think my first experience of it was Washington DC where in the 1960's there were still temporary buildings on the Mall from the war, (we joked that it was the War of 1812...)  Lady Bird Johnson managed to get rid of them!

I am guilty of it too; which is why I try to do permanent solutions instead of a temporary ones when I can.  I was once working on paining my 100 year old house's eaves, a neighbor was having theirs done by Pro's and the professionals were watching me do mine:  scraping down to bare wood, two coats oil based primer, two coats final colour. all about 30' off the ground.  They came over and talked to me at one point. Told me that had discussed making me an offer to paint my eaves; but after seeing how I did it; they decided I wouldn't like their job.  You see I hated the painting so much that I was determined that I would NEVER have to do it again!  (Next owner covered all the wood with vinyl...)

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Once I acquired the infrared heaters, I haven't even used the stove.  So my temporary setup will be changing, just need to remove the pipe (as you suggested Thomas).

Frosty, No attempt was made to quiet what I did.  I explained my actions and thanked you all for the input.  I wasn't looking for "Oos and aaws of admiration"!  I was merely posting to show what has worked for me.  Ideally, no, it's not the best and whether or not it is to code or acceptable by others, doesn't bother me.  I was being very polite in my replies so your reply seems unprovoked (in my opinion).  Again, I appreciate the information and accept all comments. 

This forum is about learning and doing something different.  I built my entire setup from reading threads on this forum (minus the wood stove).  Just trying to show a different approach. That is all.

Kind regards, Adam.

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Not to beat a dead dog, but what caught my eye is never downsize your pipe. You can go from smaller to bigger, but not the opposite.

For what it's worth, the reason for the negative critiques is not necessary directed at you, but to make sure others don't follow your design.

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Kiddcaprix, can you provide the dimensions of your hood. I’m soon going to be building one for my new shop, what you built is what I have had in mind, and it looks to be performing well.

David

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Yes David, to Frazers point, just did a search and I pulled the dimensions from the drawing and info on the internet in their "plans" section for the "Super Sucker Side Draft" hood.  I may have tweaked a few of the dimensions to fit my needs, but it was pretty much exact. The one thing I have noticed that makes a difference in the hood design is the intake hole size based on the "expansion box" size.  There is some low pressure/high pressure difference that aids in the draw of the hood.  I have played a bit with, for lack of better words, adjustable shudders that I can choke down or open the size of the intake to speed up or slow down the draft.  I believe I read some discussions on the intake size vs chamber size.  This hood works really well.  My other option was to make a big hood that hung over the forge.  I wanted the space available  above and did the side draft hood.   Glad I did. 

To add to anvils comments, the pipe is 10" all the way from hood to vent.  The homemade "thimble" is a 12" to 10" reducer to give me air space around the 10" that passes through the center.  I agree that sharing the single pass through between the 2 different heat sources is/was not a good idea and have since change it (I now have propane infrared heaters instead of the wood burner). 

Thanks twistedwillow. 

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That's one of the area's that had me a little concerned. At your discretion, at some point you may want to replace just that section where you're going through the wall with some double walled stove pipe and then add your "thimble" around that. When I put my chimney in I needed 2" clearance to combustibles at the penetration and that was with blanket insulated double walled stove pipe, not single walled spiral duct.. 

Just thinking out loud here. 

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Frazer, I had the same concerns with the 12” thimble… It basically creates a double wall flue, that by code still requires additional clearance. Personally, I’ve got way too much money tied up in this not to have everything up to code.

Frazer/kiddcaprix, it took a little digging, but I believe I found the plans you followed on another site… Thanks!

David

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I defiantly want to have as much air space as I can around the 10" pass thru.  When I was "building" the thimble in the big box duct isle, I wasn't sure the space claim I had and what I could actually fit between the studs.  I was looking at it last night and realized I have a few more inches of space on each side so I may be able to to a 14" reducer in there with the 10" down the center.  I have a big roll of ceramic insulation I was gonna wrap the 10" with.  Essentially creating a double wall.  After looking at some store bought thimbles, I was thinking of drilling some big(ish) holes (~1" space axially) in the reducer section of the step down (inside and outside) to allow any "trapped" hot air to escape.  I would need to cover the holes with mesh to stop bug intrusion. 

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David, doing it to code is expensive and time consuming... Parts permits, inspections etc. I ended up putting in a 10" DuraVent system. . Galvalume up to the penetration and SS after.

I did a modified super sucker design to compensate for the shape of my particular forge. I cover it (in minor detail) in my thread "Frazer's Corner of the Internet".

I don't want to hijack Adams thread here.

Adam, that would probably help from a safety perspective, but getting around the lack of UL listing on the pipe is next to impossible without replacing that particular section. In my town, all of the pipe has to be UL listed to UL 103 in order to be used as stove pipe (ie. no spiral duct). But these sorts of things vary depending on the town.

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On 6/23/2021 at 4:29 PM, kiddcaprix said:

I was being very polite in my replies so your reply seems unprovoked (in my opinion). 

What I've heard since that response is rationalizations for ignoring: good building practices, code, law and legal liability, and to the devil with common sense. What you are doing is an illegal and dangerous mess that lacks even basic understanding of draft and smoke behavior. 

All this mess is you choosing cheap over doing it right and what's worse you're posting and defending it on a public forum with a membership of around 56,000 in some 150 countries around the world. You're even defending your lousy build with even worse bad modifications.

I was going to ignore you but I can't. I can NOT in good conscience leave this dangerous call it booby trap fire hazard go un challenged. Nobody, no fire inspector, building inspector, insurance agent let alone adjuster cover that lashup. 

You are NOT smarter than the people who make the fixtures to do wall and roof penetrations safely. Almost anybody can learn to use a rendering program and make flashy drawings in a few days. It does NOT mean it's anything but a disaster in waiting. A disaster you'll find yourself working much harder and paying much MUCH more defending in court than just doing it right in the first place.

So no, you're right I can't remain polite. Your irresponsibility is on your head but you're posting it where someone who doesn't know any more than you do may build a stack system like yours and lose big time. Were this my forum I would've moderated your posts to prevent you from presenting such dangerous misinformation.

Warning the public about dangerous misinformation is never "unprovoked."

Frosty The Lucky.

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38 minutes ago, Frazer said:

David, doing it to code is expensive and time consuming... Parts permits, inspections etc. I ended up putting in a 10" DuraVent system. .

Frazer, this is why I’ve had the professionals doing everything on mine down to a couple feet about the hood. They were lost when I was talking about a side draft design and were thinking 10” was over kill. That’s when I decided to do that part myself, but wanted everything else done professionally with appropriate codes followed and work warrantied. I don’t want roof leaks or fires…

David

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I had mine installed by professionals as well. I made all the drawings that were used for the permit and welded up the hood/support frame that holds up the whole assembly, but I let the professionals handle the majority of the the smokey bits and all of the assembly. Once you get the parts in they're basically legos, but having it done by professions takes some of the liability off your shoulders and they know the ins and outs of the whole process with the code office (or in my case the fire marshal.. the code office passed the buck because they didn't know how to handle a "forge"), where I admittedly do not.

That's funny, my guys were also confused about the side draft. They said, "... So... where does the fire go?" :rolleyes: Needless to say there was a good deal of explanation required to get them on board with the whole concept. 

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Posted (edited)

Well Frosty, thank you for enlightening me on the way a public forum works.  If I am the only one on this forum that has ignored "good building practices, code, law and legal liability, and to the devil with common sense" then I will humbly remove myself from this forum and the internet all together. 

I never stated I was smarter then anyone who makes the fixtures/duct work/thimbles.  I don't see this setup being any worse than a pass thru wall hood with zero clearance right next to the heat.  That is only my opinion, wrong, right, or indifferent!  You may be correct in the fact that I have a "dangerous mess that lacks even basic understanding of draft and smoke behavior" but I sleep fine at night with this setup.  Last time I checked, smoke rises.  I don't believe "smoke behavior" is any different in Michigan as it is in Alaska!  But that could be my "basic understanding" of it in which I seem to lack.  I do this as a hobby with the funds and knowledge to preform it as such.  It may not be what YOU would do and I respect your opinion and will leave it at that.  You seem to have a lot of answers/opinions for this forum and I am surprised you are not a moderator!  I don't apologize for what I posted, and anybody has the right to speak freely on the matter.  Never once did I say to do it this way.  Is it to code? No.  Is it the worst idea ever? Based on your comments one would assume so, but I doubt it.  Is it going to burn up the moment I light a match in it? No.  Slap a "STUPID IDEA" sticker right at the beginning of the post, I am fine with that.  It won't stop me from enjoying this hobby. 

And FWIW, my drawings were done with pens and markers by hand!   Please, by all means, "learn to use a rendering program and make flashy drawings in a few days."  I would love to see your work!  

Regards,

Adam

1 hour ago, Frazer said:

Adam, that would probably help from a safety perspective, but getting around the lack of UL listing on the pipe is next to impossible without replacing that particular section. In my town, all of the pipe has to be UL listed to UL 103 in order to be used as stove pipe (ie. no spiral duct). But these sorts of things vary depending on the town.

I would agree with that, a double wall section would be better than the spiral.  Thanks for the info.

Edited by Mod34
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