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I Modified My Buck Stove 27000 Insert for Secondary Burn. Now Have Questions

Post in 'Classic Wood Stove Forums (prior to approx. 1993)' started by boatboy63, Dec 19, 2010.

  1. boatboy63

    boatboy63 Member

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    We have an old 27000 model Buck Stove insert mounted in the fireplace opening. It has been there for years and was probably built in the early 80's. After reading on here for the last couple of years, I decided to try something with the old stove. I know this isn't an EPA model and isn't very efficient, but it is here and not costing anything to use. I started reading about secondary burn and gasifiers and got my mind to working. I started looking at the stove and trying to get something going in my head that would work.

    I finally ended up with a game plan of drilling a 1 1/4" hole on each side of the doors just above the floor level of the inside of the stove. I then used a total of about 9' of 1" black pipe and elbows and couplers to connect inside of the stove. I laid all this out from the outside of the stove and tightened all fittings. I drilled a total of about 32 1/8" holes (3 rows) along the bottom side of the 18" section of pipe on the top front of the stove. I stuck the pipe thru the holes at the base and used 1" conduit nuts to secure to outside frame. The piping ran about 15" to the rear on each inside corner, connected an elbow, then went about 15" up to another elbow, and then about 10" forward. This was done on each side of the stove. At this point on each side, I installed an elbow on each end and connected about 18" of pipe. If anyone has ever dealt with this specific model of stove, you know it has a large firebox, a damper at the top of the stove with 5 positions ranging from wide open to totally shut. It has a slide on the lower part of each door to adjust primary air flow coming in.

    After completing all this, it was time to build a fire. After the kindling took off, I put about 4 medium sized splits into the stove, pulled the top damper to about the 2nd notch from being fully open and opened both bottom slides all the way to get it going. About 15 minutes later, the fire was raging so I pulled the top damper lever out to the 4th notch and slid both bottom slides to about 1/3 - 1/4 of the way open. By leaning down and looking up thru the glass doors (I cleaned them while they were out for the install), I could see flames dancing at the top right side of the piping from around where the holes were. I continued keeping an eye on this thru the day. I only saw flames near the left holes a couple of times all day, but saw them around the right side thru about 1/3 - 1/2 of the burn. I did notice that if I allowed the actual flame tips from the flaming wood to reduce, I had no flames at the top of the stove. I would open the lower slides some and when the flames got tall enough (from the splits) to touch near the pipe holes, the fire would again dance around the holes.

    I did this modification a week ago tomorrow and my results are hard to judge. I think we have been using about the same amount of wood, but it has been colder this week compared to last week. For the most part, the blower has been running on high just about all day due to the cold outside. The stove is currently used about 12 hours a day because it will not supply heat to rear side of the house so we have to let it die down so heat can come on and warm that side of house. Prior to doing the mod, we would empty ashes about every 3 days. We have now had a fire for 6 days and have slightly less than we used to after 3 days. The fire seems to be burning hotter, but I am still only seeing fire at the top holes when flames from the wood come up and ignite it. The left side of holes are still not firing like the right side are. I have an idea why but am not sure. When I put the pipe in during the install, I noticed the pipe holes on the left side were facing more forward than I wanted so I took a pipe wrench and turned the left nipple about 15* toward the back. By turning it this way, it would have loosened the pipe slightly from the top left elbow. I didn't think it would have been enough to bother anything, but I am seldom getting any burn from the left side. I thought I would give it a week so it could heat up, expand, and fill any minor leaks with ash that would get in there. We had plans on leaving for awhile today, so I filled the stove about 80% full and it was running on high when we left. We returned 5 hours later and still had at least an hour of hot coals left and fan was running on medium. I was happy with that.

    Since the week will be over tomorrow, I am open to suggestions on what to try. I am thinking about taking some small screws and filling about 8 of the 32 holes to see if it will help any. As I said before, if I can keep flame tips from wood high enough to touch near these holes, the gasses will light. In order to do this, I either have to fill the stove full or leave the slides open more which results in the wood burning faster. I can fill the stove half full and get it hot enough for fan to stay on high so any additional wood is just wasted heat. Any suggestions would be appreciated. Thanks. BTW, I am building a gasification boiler to go outside and run to an hx in my forced air system. The problem is that I got off to a later start than planned and winter has actually struck a month earlier than normal.

    Edit/ added pics of piping and holes.

    Attached Files:

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  2. gzecc

    gzecc Minister of Fire

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    How about a picture of this mod?
  3. boatboy63

    boatboy63 Member

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    I am going to take a few in the morning when it cools and I clean the ash out. I know a pic is worth 1000 words and I guess I nearly used that many.
  4. gzecc

    gzecc Minister of Fire

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    Measure the front door opening, Ill tell you the model #.
  5. boatboy63

    boatboy63 Member

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    14" tall and 19 3/4" wide
  6. gzecc

    gzecc Minister of Fire

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  7. boatboy63

    boatboy63 Member

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    Ok, pics posted in original post before plugging some holes. New pics in this post. As you can see, I plugged a whole row of 11 holes with 1/8" steel rivets. There are still 21 holes remaining but they are aimed toward the damper and diagonally toward the back. Can't really tell much difference so far, but have seen gasses ignite a few times. Don't know if it will make any difference or not, but the 1 1/4" holes coming thru the front of the stove are not sealed. I am sure there is some leakage around them, but will have to get some caulk suitable for high temps.

    Attached Files:

  8. gzecc

    gzecc Minister of Fire

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    Very interesting. What is the objective in theory? Is there a way to gauge the results?
  9. WES999

    WES999 Minister of Fire

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    I added a secondary air tubes and baffle on my Fisher stove.
    I will post some pics later.
    I think the reason you are not seeing good secondary burn is two reasons,
    It looks like there is not an insulated baffle above the air tubes, I think you need a baffle to increase the heat at the top of the stove to achieve good secondary burn.

    Also you may not have enough secondary air volume. On my conversion I have 3 1.25" holes feeding into a 3" x 3" x 23" chamber that feeds the 4 air tubes.

    Attached Files:

  10. boatboy63

    boatboy63 Member

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    The objective was to redesign the wheel. Actually, as everyone knows, these old stoves love to eat and did wonders during their time. Efficiency was no issue back then.

    I wanted to try and make it burn more efficiently and use less wood. I know it burns hotter and it has cut the amount of ash in half. In theory, when the stove gets to temp, it would heat the air in the pipe causing it to rise and pull fresh from the outside holes. As the heated air is "sucked" out of the holes in the top of the pipe, it would do a secondary burn at the top of the stove, reducing the smoke and creating hotter burn temps. Over in "The Boiler Room", some members had done this mod to a Clayton/HotBlast furnace and it has been very successful. As I said previously, I am building an outdoor gasification boiler but it is on hold for now due to the weather. This was just a cheap mod I could do to see what would happen. I had the time, but didn't have the money to replace the stove. I know many people who own older stoves have wondered about doing something like this, but they just aren't as crazy as I am to go thru with it.
  11. boatboy63

    boatboy63 Member

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    Thanks Wes. Do you have any pics of it doing a secondary burn? What kind of temp/efficiency difference did you find? I do have plenty of 1/4" plate (about 15,000 pounds) just laying around. I may take a piece and cut it to fit above the piping. I will have to be careful and not get into the damper linkage and bind it's operation. Am trying to install new ductwork throughout the house right now so guess the old stove project will go on hold until ductwork is done.
  12. gzecc

    gzecc Minister of Fire

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    Boatboy, Its very interesting. I have a 28000 buck. Didn't even know it was possible to try something like this. Keep us updated. Thanks.
  13. WES999

    WES999 Minister of Fire

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    I installed a 3" X 3" window in the door of the stove, it is a bit small to take a decent pic through.
    When you look in you can definitely see a good secondary burn. BTW my baffle is made form 1/4 stainless steel covered with 2 layers of 1/4" kaowool. I also added 2 layers of kaowool behind/underneath the original fire brick.

    It is hard to make a exact determination of the improvement but it does seem to heat the stove more( higher stove top temps) and the flue less ( lower flue temps).

    Attached Files:

  14. valley ranch

    valley ranch Feeling the Heat

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    Greetings boatboy, I'm wondering why you haven't a tube or two more, at least one close to the back of the firebox where the hot gasses are headed on their way out of the stove. The size of your tubing should be good, some guys on this forum have done well with that size. I would put holes on the side pipes coming forward. Good luck with it, I think what you're doing will improve the burn.
    Last edited: Jan 7, 2014
  15. Kevin Okes

    Kevin Okes New Member

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    I have both a 2700 insert and a 28000 free standing stove. I burn quite a bit of wood. Keeping new ropes and tight seals works pretty well to make them "efficient." I don't want to invest the money in a new stove. Buck says they will not modify old stoves (big surprise). Yours is the only post I've found, believe me I've been doing my homework, of doing a retrofit on a Buck Stove. None of the other stoves have the air jackets of a Buck. Your idea seams to have worked and I'm wondering if you've done more to the stove since your original post and it worked better. I would like to try something when I'm not burning wood if I thought it could make the stoves more efficient and not need to clean chimney as often.

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