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Slammer modifications

Post in 'Classic Wood Stove Forums (prior to approx. 1993)' started by grizzle, Sep 25, 2013.

  1. grizzle

    grizzle New Member

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    I've been searching and reading through the forums, but I'm still looking for some advice and a sanity check as I'm new to wood heating.

    Just moved into a new house in Maryland last year, didn't get anything figured out before last winter so we just ran the heat pump. I've got two large masonry fireplaces above each other in a 1972 rancher. In the basement I'd like to use the old Black Bart II slammer stove insert I've got for a couple years until I can afford a better more efficient stove, but not until I've run a full liner and cleaned the chimney.

    My plan is to cut a round opening and weld on an 8" boot or collar directly onto the top of the stove and close in the remaining area from the old 4"x14" opening with steel plate as thick as the stove, then run an 8" flexible stainless 23-25' liner to connect to the boot and make/install a blockoff plate. There is currently no damper in the stove, and I wasn't planning to add one. Both fireplaces have 11"x11" ID clay liners that look decent, just dirty and for the time being I was going to simply not use the upstairs fireplace. Also, the original damper plate is missing and I don't ever intend to use it without and insert, so I will probably just cut whatever hole I need to run the liner through the old damper plate frame or knock out a few of the bricks from behind the damper plate frame in order to eliminate/minimize ovalizing.

    I also plan to cut some holes in the ceiling above the stove in the basement which would be into a large kitchen and force the hot air to move through gates, and circulate with fan only from air handler unit.

    Long term I would like to be able to upgrade the stove and use the liner I get now(8"). I really don't want to spend much of anything on the old stove itself besides some 1200° black paint, new gaskets, and a very cheap one speed blower that I rig up to the back.....

    Any words of caution or affirmation would be appreciated.

    I can also post some pictures if anyone is interested.


    -Black Bart II
    -Fiskars x27
    -Homelite SuperXL Automatic 20"
    -Craftsman 18"
    Last edited: Sep 25, 2013

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  2. Corey

    Corey Minister of Fire

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    I cut out the square opening in my insert and welded in a round collar for 6" pipe. Assuming you can cut metal and weld with a decent quality, it shouldn't be a problem. My mod was a bit more complex as this is an insert (double walled), so I cut out holes for enough clearance and welded the firebox from both sides, the patched in the outer skin and welded / ground it on the outside. Been running long and hard for many years with no issues. I picked up some scrap stainless and made a secondary air system and air wash for the glass - definitely a huge boost in efficiency.

    The only 'catch' for me was that 6" Sch 40 steel pipe didn't seem to really fit the stove pipe - way too loose. So I had to section out a ~1/2" piece of the collar and weld the ends together, then grind smooth.
  3. Corey

    Corey Minister of Fire

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    PS - someone will likely be along soon to mention the fire hazards associated with cutting air passages through the floor to get hot air upstairs. The holes generally work just as well for smoke and flame as hot air. So use at your own risk.
  4. central_scrutinizer

    central_scrutinizer Member

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    It would be easier to use one of these round insert boots to make the connection than to cut on the stove. The person you sell the stove to in the future (if you sell it) may need to use it as a free-standing stove and cutting it up would lessen your chances of getting rid of it. You can always use the insert boot for your next stove. Just a thought.

    Attached Files:

  5. grizzle

    grizzle New Member

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    Thanx to everyone for the feedback so far!

    I'm sure it would be easier and I do have enough clearance to make it fit. However, given the overall money situation and the fact that I weld decently well, I can make the 4"x14" to 8" round modifications without allotting any more money, just time. I'm already budgeting around $1000 for the 25' flexible stainless 8" liner with insulation and 13x13 terra cotta deluxe flip open rain cap. BTW: If anyone could suggest which liner to go with and the best place to buy these parts that would be great.

    Also, I don't plan to ever sell the stove to anyone else. When it does come time to replace it with something nicer I'd probably just move it upstairs into the fireplace directly above. (Note: the two fireplaces share the same masonry, but have two separate 11x11 ID clay lined chimneys that run roughly parallel)
  6. Corey

    Corey Minister of Fire

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    Also something to note: With that tall of chimney AND insulation AND a stove without a damper AND on old stove with minimal or no baffle - all these things combined will make it draft like a jet engine. ... the jet engine where that guy got sucked off his feet and pulled right inside.

    If it were me, I 'd seriously consider making a 6" flue collar. I would suspect you're still going to have plenty of draft, the 6" is very common if you buy a newer stove, it would fit right up and you would not have to replace the entire liner and insulation at a later date, and it's likely much cheaper than the 8" liner.
  7. grizzle

    grizzle New Member

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    Let me start over. I guess I was of the impression that draft was good. Didn't know you could have too much.

    Please let me understand this right. You are suggesting that I convert the insert to a 6" flue collar/boot and running a 6" liner vice the 8" I had been thinking of getting?

    Please also take a look at these pictures as I may not be explaining things just right. From the floor of the fireplace in the basement is 25' as the tapemeasure hangs. The chimney in question is all masonry which is shared by the upstairs chimney which is 17' to the floor of that fireplace. Both are 11"x11" clay lined with only small stress/age cracks. The basement chimney is also staggered or offset to the right at least 12" to the point it was a little tricky pushing down a tapemeasure from the top. I plan on running an insulated flexible stainless liner to the basement to attach to a slammer style Black Bart II. The house is a 1972 rancher with a full unfinished basement. I new to wood burning for heat, but I am quite handy and I weld decently well.

    Note: The insert has had very little use and seems very solid (no cracking, warping, or signs of repairs) it was however somewhat rusty from sitting in a barn so I've wire brushed and painted with 1200° paint the exterior and doors. I also need to figure out a new blower fan, and I have about 12" behind the insert, so that shouldn't be a problem to rig up.

    Thanx again for all the advice.

    Attached Files:

  8. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    What you run into is draft that the guys that designed those inserts never dreamed would happen. I did the same thing with my big insert I had burned in for twenty years. With a six inch 21 foot liner and cast iron adapter boot. And right off the bat that sucker was out of control. Went through sheer terror the first two nights in a row when it ran away on me and the stove came out of the fireplace and was replaced with a new one.

    It may work fine. But be careful.
  9. gzecc

    gzecc Minister of Fire

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    Weld a damper into it. If you don't you'll have no control and use wood like crazy.
  10. Corey

    Corey Minister of Fire

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    You understand correctly. Obviously this is pretty far from an exact science. Possibly you selected 8" pipe by looking at the area of the pipe and found it's close to the area of the 4x14" stove opening? The thing to consider is the stove originally exhausted through that square opening into the firebox of a fireplace, smoke then entered a chamber and large fireplace flue. There would have likely been some leaks in the stove-to-fireplace seal and possibly other ways for air to get in the fireplace...ash doors, cracked brick, etc. All of this combines for a relatively low draft situation, hence the big opening.

    When you install the pipe, you're basically making an airtight seal and creating a smooth, uniform tube for the smoke to travel through. This is a very high draft situation. Additionally, more air = more heat = more draft and you get into a runaway situation.

    So while I can't say exactly what to do - and knowing every situation is different - I can only give some insight as to what worked for my case, which I believe is relatively similar. I burnt my stove as a slammer for a year. It had a similar sized square opening and a small steel plate about 12" wide which acted as a baffle. Though under operation, you could clearly see flames swirling around the baffle and out the hole. This is in a '73 ranch house with the chimney on a hip roof, so total height of flue is only about 13 feet.

    The first mod was to install the 6" flue collar, make a basic firebrick baffle, weld up all the leaky slide air vents and replace with a pair of tight fitting gates, and I installed one 'burn tube' at the back of the firebox. This vented into 13 foot of uninsulated stainless steel liner which ran up the old 12x12 terra cotta flue in the masonry chimney. It worked well, though there were a few tense moments under full fire on cold winter nights when slight leaks in the ashpan door would keep it firing into the 950ºF range. Conversely, I would get just a tiny amount of smoke spillage on those 'warm/humid' shoulder season burns... ie raining and 45ºF in the spring time where the warmth and humidity both reduce draft.

    After a few years, I decided I wanted a better baffle, so I made a trip to the scrap yard for some stainless, and picked up some refractory board off ebay. $40 and some cutting/welding later, I had a new 4-burn tube baffle system based on the NC-30 design. I also added liner insulation to the top 10' of liner thinking maybe I could stop the late season smoke spillage.

    The new baffle made a huge difference in burn efficiency. After a bit of learning, I could easily get the thing to light off and have an orange-hot baffle zapping every last smoke particle and extracting maximum heat energy.

    http://www.hearth.com/talk/threads/burnin-orange-tonight.106714/

    The new baffle did seem to increase smoke spillage a bit more. It was a tighter fit and the stove pipe is offset very far to the back of the firebox. But as it made more heat, it also made the runaway problem worse. So I installed a gasket on the ashpan door and added a 5' stovepipe to the top of the flue. The pipe was enough to cure the smoke spillage (now at 18 feet of flue) and the gasket cured the runaway issues. On the cold nights, a good hard burn generally kicks in with one gate open to allow an opening about the size of a quarter or a bit less and the air wash has 4 holes about 3/8" in diameter. So overall about 0.75 square inches of air inlet opening, plus a few very slight leaks

    So, going back to your mod, switching to the stainless pipe with insulation and maybe 23 feet of actual flue pipe, but just minimal baffling in the stove (do you have a good pic of it's insides?) I strongly suspect you'll have plenty of draft in a 6" pipe. Though this is free advice over the internet, so take it for what it's worth!

    PS - if you just painted the stove, hook up some pipe and fire it outside or on a warm day when you can open the house windows. Fresh paint will outgas quite a bit. If it's cold and the house shut up, you will get a headache...or worse from the fumes.
    Last edited: Sep 28, 2013
  11. grizzle

    grizzle New Member

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    I'm feeling better about going 6" for everything(collar/liner)... And it will cost a bit less too. I was also planning to fire it up out in the yard before bringing it inside, but thanxs for looking out.

    Still not sure if I need a damper or not, I could easily cut a round piece of 1/4" or 3/8" plate and weld it onto a rod but if I don't need to I'd rather not waste the time... the front air inlets look like they should close up decently tight as well. I've also put new gasket around the steel plate "windows" and the doors. The half inch rope gasket actually fits so nicely in the grooves on the doors I don't think I'll even need to use any furnace cement...

    Concerning baffles, the only thing it had was a 3" wide piece of steel tacked in at a 45° angle up by the doors... Nothing back by the flue opening. Any science behind baffle placement or design? Could I just weld in a small piece of angle iron along each side and then rest some pieces across across? btw, the fire box is 19" tall, 25" wife in the front, 18" wide in the back and 14" deep. There is no ash door, just a 1/4" thick U shaped (shovel sized) piece that sits on the bottom to keep the logs off the floor I'm assuming.

    I'm basically just looking to create whatever heat I can in the basment and circulate that around the house with my heat pump's air handler blower, thinking of using the small fan like in the picture mounted to the back of the stove where the old fan was with a three speed switch that I control manually.

    Attached Files:

  12. Corey

    Corey Minister of Fire

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    Again, this isn't science fact, but IMHO there are a couple of ideas behind a baffle:

    1) Keep fire, flame and sparks from going directly up the flue. If you see flame going directly up the flue, that is also heat going directly up the flue. This is not necessarily a bad thing if you need the draft, but if you don't need the draft, you are just wasting heat literally up the flue.

    2) If you do have any creosote build-up, there is nothing like raw flames and sparks going up the flue to really light it off. So ideally, the baffle directs flame / sparks to a route where they can't go directly up the flue.

    3) If you have burn tubes.the baffle provides a place to gather heat and help light off any smoke for a cleaner burn. It also makes the smoke take a longer route which allows more time for combustion further increasing efficiency..

    4) The baffle directs the fire/flame to the front of the stove. This means the majority of the heat comes out the front which is generally a good thing for stoves and a really good thing for inserts.

    5) Hitting the front of the stove, the heat then has to take a long path back to the flue, giving it the maximum amount of time and distance to transfer heat to the metal. Again extracting more heat and allowing more efficiency.

    Just eyeballing your stove, it kind of reminds me of an old freestanding 'fireplace' I used to have. The thing was a steel box like a stove, but with bi-fold 'fireplace' doors. It had a small 'baffle' sticking out about 6" from the back wall and running the width of the firebox. It went up through about 16 ft of flue. Pretty fire, but absolutely no heat...unless I closed the damper about 2/3, then it would settle down and make some decent heat.

    Depending on how tight you think your stove seals, you may or may not need the damper. Though going back to my stove as a reference, it needs to be sealed pretty tight! I'm actually considering adding a damper for this fall - just to add a little more control over the burn when it's really cold and drafting hard. If I were in your position, I'd probably put one in as it looks like that stove has a really straight shot up the flue. My old 'fireplace' flue almost felt like it had a 'detent' or a 'notch' about 2/3 closed - it would easily swing to that position, then required just a bit more force to push closed. Worked out really well and kept it from going all the way closed on accident.
  13. mellow

    mellow Resident Stove Connoisseur

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    Adding a baffle to the BB is going to be tricky as it has no firebrick to support a free standing baffle, not to mention it has a crazy angle to it (not square like a fisher). You would need to weld up a piece of plate steel to act as a baffle, what concerns me about this is how light those BB stoves are, not thick steel like the other stoves, they were designed to have no damper and run as hard as the draft would allow. Since this is an insert install putting an inline damper will be a challenge, it can be done however, I have seen some guys just put 5" key damper IN the liner to help slow down the draft.

    Don't count on the air handler dispersing the heat, a lot of heat will be lost to the ducts.
  14. grizzle

    grizzle New Member

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    So I finally found some 3/16" thick steel (well casing?) pipe to use for a damper housing/boot. Had to cut out about 7/8" of the side and weld the ring back together to get a 6" interior diameter and 6.5" tall piece. I plan to cut another piece and do the same only about 1" tall to weld onto the insert to be the actual boot. Then I'll cut another piece about 3" long and widen it to act as a female coupler. Which would bring me up to about 3/8" thick for the first 3" off the top of the insert. All that is to say, how thick of a damper plate should I make? I have everything up to 1/2" thick plate on hand already.

    Concerning baffles I'm still not sure what exactly I'll do, but I'm thinking of adding fire brick to the walls and sand to the floor. Might just do a simple angle iron frame/shelf to hold more fire brick about 3" from the top loosely suspended from more angle iron on the sides.
  15. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    Along the way some fool, I guess it has to be me, has to chime in and say for around a grand you could buy a new efficient insert that heats better, uses less wood and makes a cruded up chimney a non-worry.

    <ducking under my desk>
  16. webby3650

    webby3650 Master of Fire

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    This happened to my Fisher. Everything was fine until one night I woke to a hot smell. Came in the front room to find a see-thru stove! The entire thing was glowing!!!!!
    I didn't have a pipe damper or gasket on the door. Everyone says that a Fisher shouldn't have a gasket, but they do if they are worn at all! I will gasket them all now. If it wasn't on cement and surrounded by stone I don't know what I would have done.
  17. webby3650

    webby3650 Master of Fire

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    By the way, it went away shortly after that! Now it's got a shiny new stove there!
  18. grizzle

    grizzle New Member

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    No need to hide, I won't take offense at any constructive advice. The long term goal is to eventually get a very efficient big insert/stove to go in the basement and move my frankenstein black bart II upstairs into the kitchen as a backup/conversation piece. I'm going to get the liner purchased and installed before the snow starts falling... if everything works out right, but buying another stove isn't really an option for me this year. I picked up the black bart II for less than the cost of a tank of gas and I've got access to plenty of scrap steel and welding equipment...I also enjoy tinkering with things that most people see as lost causes (just because I can)....

    Any advice on how thick to make the damper plate? I'm kinda leaning towards 3/16" steel plate right now...
  19. Corey

    Corey Minister of Fire

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    Considering my liner is 0.005" thick, I think 3/16" or 0.187" should be WAY more than enough for a simple damper plate.
    grizzle likes this.
  20. grizzle

    grizzle New Member

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    Since I had some time last night as it was raining, I decided to start on some of the boot/collar conversion. So from the piece of 3/16" steel pipe I had already had sized down to 6" I cut a piece 1.5" to be the permanent boot to be welded onto the stove. The remaining 5" long piece I attached a 2.5" tall piece of the original sized pipe which was cut open like a "C". I then welded it all together and filed the 1/2" gap with a small piece from the original downsizing. When I test fit it together it fits so nicely I'm not sure it would need anything added to make an airtight seal. Keep in mind this all started as a piece of 6.5" rusted well casing.
    IMG_20131017_195341.jpg IMG_20131017_235837.jpg
    Planning to have some free time this weekend, so I'll probably weld on the collar, patch the top opening, make the damper and start thinking about baffle designs... more to follow
  21. Corey

    Corey Minister of Fire

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    Having trouble seeing where all these pieces are going to fit, but i guess it will clear up soon enough. Generally, there is the collar coming out of the stove, the liner is fitted with a crimped end and that end goes in the stove collar.

    Also, you are planning to cut out the rectangle so the 6" collar has a full opening into the stove? Having it choked down to the slot might be starting to go a bit far in cutting down the draft.
  22. grizzle

    grizzle New Member

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    So I guess what I did was make a collar that is attached to the stove and then made an inline damper housing that is the same size as the collar for the stainless liner to fit to. I also cut out a 3/16" thick damper plate that I'll attach to a rod of some sort.

    Edit: yes, I'm going to finish grinding the top smooth, and covering the whole thing with paint.

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  23. LeonMSPT

    LeonMSPT Minister of Fire

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    There's that much smoke and fire in the house, it's going to get where it's headed pretty darned fast anyway. I wouldn't sweat unprotected vertical openings in single family residences... Especially if the house, or if the house, is equipped with working smoke detectors... You'll be out of the house and the fire department will be on the way LOOOONG before that's ever an issue. ;)
  24. begreen

    begreen Mooderator Staff Member

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    The damper plate should not be solid. You never want to be able to block off 100% of the flue gases. That could end up with a fatal situation. Take a look at pipe dampers and you will see they fit loosely in the pipe and have holes in them. This is to allow at least some (20%?) of the flue gases to pass even when in the closed position.
    damper.jpg damper2.jpg
    In many jurisdictions fusible link fire dampers are required for between floor register penetrations.

    images.jpg
    Last edited: Oct 21, 2013
  25. tfdchief

    tfdchief Minister of Fire

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    Point of reference. I have a Buck 26000 and my son a Buck 27000. Both were slammer installs for many years. No problems and no chimney fires. However, not the best set up. Chimneys got real dirty. Just the best at the time. Sometime in the 21st century, I did what I wanted to do day one, but at that time was unheard of, direct connect my slammer. So I custom made a rectangular to round boot, installed a 7 in. S/S liner inside my 8 in triple wall chimney and direct connected my old slammer.....perfect. Draw was perfect and the stove became more efficient. Chimney stayed much cleaner. We did the same to my son's. Details....Mine was a Buck 26000 and my son's a 27000. Connected mine to a 7 in S/S liner up my Majestic Zero Clearance Fireplace 8 in triple wall chimney. My son's, we had to go down to a 6 in S/S liner slightly ovaled to get it down his masonry chimney. Mine draws great and as I said is better than ever. Son's, a little low on draw and on start up can smoke a little. Draws and burns great with the doors shut however, and stays much cleaner.
    grizzle likes this.

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