secondary burn tubes

BAllen83 said:

Thanks Cory. Gonna try and get some plans and im gonna give this a shot. Still tryin to find out if it can be done on a rear exit stove.

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I suppose it 'can' be done, though you will need to leave some offset between the top baffle and the back wall where the flue is. Whereas with a top exit, the only concern is leaving a space between the top of the stove and the top of the baffle/tubes. Depending on how big your firebox was to begin with and if the reduction in size is acceptable. I would say allow at least a couple inches of space in each dimension, plus figuring the back wall and top baffle may be a couple of inches thick additionally, this could mean taking 3-4 inches off each dimension.

If that makes things too small, it's not too hard to convert over to a top exit while you're cutting and welding secondaries anyway. I actually converted from a ~3x14" rectangular hole 'slammer' to a standard 6" flue collar.

I don't know how much top clearance you have but along the lines of what Corey is thinking with the top exit, you could remove the smoke collar you have now and close up the hole. Then weld up a box with the bottom open and a 6' round outlet coming out of the back, cut a hole it the top of the stove and weld (or bolt) this box over it so you would have a top/rear out let or a top outlet that points back. I guess that may ruin the look of the stove but it's and idea. You could also design this top outlet box in a manner that would allow for that addition of a cat and a bypass at a later date if you decided that you needed one.

I'm not sure how long they would last but if the price is rite it's worth a shot in my opinion. Just make them so they are easy to change out.

If it is thick enough, mild steel would work...at least for a moderate amount of time. If you could get 1" sch 40 pipe, it would have a wall thickness just over 1/8 inch. Would probably get you a couple years of use before it burns through. The down side is, ideally you want the tubes to be thin, so they heat up fast and start burning smoke quickly. Having the 'mass' to hold the heat isn't really a factor because the coaling stage of the fire is pretty clean anyway.

If you can hit a scrap yard and find some thin wall stainless, it would be ideal, or even prowl around ebay. You can usually find a 4-6ft stick of 3/4 or 1" dia tubing for under $30. I got some sections of 2"x2"x1/8" wall square stainless to make my frame and some 1" round stainless tube to cut up into burn tubes.

If you know how to spot it (I can show people, but I have no luck writing a text description) stainless is often cheap at a scrap yard (if they even take it.) You may also find that you can pick some up as a manufactured product, cheaper than you can buy the raw stock - tub/bathroom handicap grab bars come to mind. Generally a non-magnetic stainless will hold up better than a magnetic stainless, and if you're sourcing your material this way, that will be about all you know about the alloy in most cases (if you bring a magnet.)

I would think that using the secondary supply tubes (not the thinner burn tubes, if the burn tubes are quite thin - if they'll take the abuse of having wood dumped on them when hot, thick enough) as a grate would be a good approach to at least part of the preheat for the secondary air.

I used .75 x .06 wall 304 stainless tube for my Fisher conversion.
I purchased from here:
http://www.onlinemetals.com/merchant.cfm?pid=471&step=4&showunits=inches&id=19&top_cat=1
I think I got 2 4' lengths, cost about $40, it should last almost forever.

Corey good go! I think adding secondary is the way to go for guy with great old stoves. There are also some nice videos on the net, google and see what you can find. I've seen some quickie jobs and some take your time mods. The all work, some better, some great.

Richard

BAllen23, I'm working on doing the same thing to my Sierra 1000 as well. Currently I'm building a firebrick baffle to replace the old worn out metal one in the stove. I think I now have devised a way of mounting it loosely but securely without welding it specifically though I do need to weld a strip across the bottom of the old baffle where I've cut it off. I figure I can test/modify/move it this way and get it's design ready first before messing with secondary burn tubes. The baffle will be 4 firebricks set in a steel angle holder and will lean toward to where the sloped top plate meets the flat top plate with about a 3 inch gap left. I plan to cap the ends with firebrick as well to even the distances up around the baffle. Also I talked to a customer at work who builds furnace parts and he's going to bring me some scrap ceramic boards they use as liners so I may just end up using that as a baffle instead of the fire bricks. I just need to test it so I know if my baffle will work the way I want it too without smoking up the house or something, then it's secondary time. Luckily I have most of the materials already. We cut some 1 1/2" stainless tubing at work last week and had about 8 pieces around 3 feet long left over. A few of those will make the manifold portion of my secondaries. For the air tubes I can get 1/2" stainless tubing all day long, we go through miles of the stuff at work and I don't need very long lengths. I probably won't get to the secondaries until after the burning season though. I like to sit on an idea for a while and see if it gels in my head. Plus it will be nice to have a comparison between before and after. I really look forward to it. This stove is of an odd design, but it sure fits right. And so far I only have about $200 in the whole thing and need to spend about $100 more for glass and some more fire bricks. I hope it's not a $300 disaster, we'll see.

Greetings Shwammy, Just read your post. I can't picture it well, hope you can post pictures. I used a Sierra Benzel or frame when I put glass in the door of my stove. Good luck with the modification. Talk to you later.

Richard

The stove is a side door rear exit like in the OP's avatar. The new baffle is just an 18'' wide x 9'' tall steel angle frame with 4 firebricks laid in it instead of the old 10'' wide x 10'' tall steel baffle. It will sit up at around a 60 degree angle or so (not sure on that yet its more of an eyeballing thing). The bottom of the baffle will sitting partly against where I cut off the bottom inch of the old baffle plate so it will actually be taller There will be bricks cut into triangles sitting on the ends filling the gap from the main part of the baffle to the back wall. This will look like an 18'' wide upside down dryer vent and cause the fire and smoke to travel a much further path as it exits and provide me room to mount secondaries down the underside of the baffles. Before it was just a rectangular box with a piece of steel mounted in it that more or less just kept the flue from being blocked off by an overzealous loader. Now it will have a baffle/smoke shelf which won't be too much of a space hog but will be effective with the rear exit...in theory. I'll take some pics when I get a chance. I'm trying to have the thing finished this weekend, minus the secondaries.

Sounds great, good for you, get it done.

Richard