1. Welcome Hearth.com Guests and Visitors - Please enjoy our forums!
    Hearth.com GOLD Sponsors who help bring the site content to you:
    Hearthstone Soapstone and Cast-Iron stoves( Wood, Gas or Pellet Stoves and Inserts)

Burning coal in a Buderus boiler

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by sparke, Jul 8, 2006.

Thread Status:
Not open for further replies.
  1. sparke

    sparke Minister of Fire

    Joined:
    Jul 6, 2006
    Messages:
    565
    Loc:
    Maine
    Hello, My first post here. Nice place!!! Ok to my questions, I have a Buderus Logana add on boiler. It is rated to burn wood or coal. The boiler DOES NOT have shaker grates. The manual says that you are supposed to use a riddling tool (which I dont have and Buderus doesnt sell anymore). Everytime I try to burn coal, I fail miserably. At the end of the day the coal never fully ignites and goes out leaving almost full size clunkers. I use a 1/2" tubular shaped tool with a 90* bend on it to riddle. The boiler has holes at the bottom of the coal bed which to insert the tool. I run the tool horizontally on the grates until I see red coals start to drop.

    1. Is it feasible to burn coal in this boiler with out shaker grates.
    2. Possible low draft problem?
    3. Open secondary draft (located above coal bed on the door) more?
    4. Different ridding tool?
    5. Is the poor burn a result of not shaking (which I cant) or ridding wrong??

    Thanks for any suggestions.

    Helpful Sponsor Ads!





  2. Corie

    Corie Minister of Fire

    Joined:
    Nov 18, 2005
    Messages:
    2,430
    Loc:
    Halifax, VA
    It sounds like a combination of problems, at least to me. First off, to rate a furnace or stove as a coal burning unit and then not include any real type of device that will remove the ashes from the coal is a joke. But besides that, if, like you said "At the end of the day the coal never fully ignites and goes out leaving almost full size clunkers" you might be doing something wrong from the get go.

    You shouldn't be adding any coal until the first layer is glowing red and dancing with blue flames. I'm unsure of how the air control on this unit is setup, but if you can't get a bed of coal to glow red with the underfire air fully open (Or the ash pan door open, if such exists) it may be possible that the poor design of the furnace with regard to burning coal may make it impossible to burn with the draft you have.

    If you could take a picture of the grate section and the riddling tool, it would help me immensly to understand the situation better!
  3. RoosterBoy

    RoosterBoy New Member

    Joined:
    Jul 5, 2006
    Messages:
    170
    Loc:
    CT
    sparke i have a buderus g115 oil fired boiler that i installed myself with the lt 160 indirect tank and 2107 odr control buderus is a fine product but i never seen there coal boilers. are you from the united states. have you tried buderus.net
    and call tech support ask for joe kanard

    thanks
    Jason
  4. HarryBack

    HarryBack New Member

    Joined:
    Dec 27, 2005
    Messages:
    990
    Loc:
    Western Massachusetts
    maybe speaking out of hand here, since ive also never run that boiler, but have run ALOT of coal stoves......so, take this post for what its worth.

    I think any real coal stove or boiler worth its salt should have shaker grates. You do need to be careful with these as well, always leaving a layer of ash on the grates to protect them from overheating. If you are shaking till you see glowing embers in the ashpan, youre shaking too much. The riddler is ok at best, if used correctly. Hard to truly shake the fire down with one without ALOT of experience.

    You DO need a pretty good draft to keep the coal running well.....draft numbers would be good here.

    Id say nix the secondary draft and see what happens....the coal is gonna want air from below the fire to fire well....see what happens without the air on top.

    Since you dont have shakable grates, research the tool, have one made, but im not a fan of riddling tools anyways. Sounds like the boiler was made with wood in mind, coal as a marketable afterthought.

    Have you tried a different brand/size of coal? Are you burning nut or stove coal? I reccommend nut to start with, if it burns out too fast, go stove. Stove coal is harder to burn, due to its size. The clinkers could be inadeqaute stirring or shaking, could be a high mineral content in the coal as well....alot of silica and salts. Salts will lower the temp at which silica fuses, thus creating more clinkers.

    Generally speaking, live coals in the ashpan is OVER shook, not UNDER shook. Maybe with no shakeable grates you have no choice, but im guessing you are overdoing the riddling.


    Good luck. maybe there are folks here that use coal in a Buderus who can help you better. Im really only experienced with shakeable grates.
  5. sparke

    sparke Minister of Fire

    Joined:
    Jul 6, 2006
    Messages:
    565
    Loc:
    Maine
    Thanks for replies. Here are some pics. I agree that it is a wood boiler with coal as an afterthought. There is a draft door on the bottom (under grates), that is controlled by the aquastat. The draft on top is manual. I dont add coal until the whole layer has blue flame. I can get the whole load going it just does not finish the burn and I know this must me 1. no shaker/bad riddling. or 2. Once the boiler is full there is not enough draft to keep the fire going. Forgot the pic of the riddler but basically it is like a wood stove tool. Picture L turned sideways:) The holes you see at the bottom (located even with the top of the grates) is where you insert the riddling tool. I have always burned wood. I have tried coal in the past but because I have had poor luck I have given up. This year I dont have any wood so I am going to be forced to learn how to burn coal. BTW, I live in Maine and just pre payed oil @ 2.30 a gallon which is a going to be cheap in a few months... OUCH!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
  6. sparke

    sparke Minister of Fire

    Joined:
    Jul 6, 2006
    Messages:
    565
    Loc:
    Maine
    Well the pics didnt post. I attached them... Time to go read the directions...
  7. webbie

    webbie Seasoned Moderator Staff Member

    Joined:
    Nov 17, 2005
    Messages:
    12,382
    Loc:
    Western Mass.
    Well, I was going to delete all the other answers, but I will wait - at least a few minutes!

    This is a GREAT coal boiler, and is in fact designed more for coal than for wood. It is a updraft, cast iron unit very similar to the SIME boilers, which are now imported under another name.

    Many of the best coal stoves in the world, including early Efel and Surdiac models, have no shaker grates. The Buderus has "wet grates", meaning water running through the grates. Not only does this transfer heat best, but it also makes for less clinkers (fused ash) because these form when coal is too hot.

    OK, so we have that out of the way...

    Yes, it is very possible you have a draft problem. Read the sections on Hearth.com about chimneys and also about staring and tending a coal fire. Also read the one about hopper-fed European stoves (for shaking techniques).

    Tell us about your chimney situation.

    I had a SIME in my house and my 2 story chimney was too weak. I installed an Exhausto fan on the top of the chimney and solved that problem. However, you might try the draft basics before this (make sure pipe is tight, chimney clean, etc. etc.).

    If you can easily start the fire and get it going then your problem might be shaking technique. Here is a hint - if that boiler does not smoke out the loading door when loading with wood, chances are your draft is decent!

    So, you start up the fire with some small hardwood, get a good bed of coals and then throw 5-10 pounds of coal on top. Make certain the draft control is full open at this time. When the coal is definitely lit and going, throw another 5-10 pounds on. When that is lit, you can fill the stove with at least another 30+ pounds. If you do not have a deep bed of coal, it WILL NOT WORK.

    Raking is done by using a poker or large flat tool as close to the top of the grates as possible - thru that little gate in the front of the coal fire when the bottom door is open. Rake or knife until a bit of red drops through the grate.

    Remember, the boiler will not work well in warmer weather - wait until below about 40 degrees if possible.
  8. sparke

    sparke Minister of Fire

    Joined:
    Jul 6, 2006
    Messages:
    565
    Loc:
    Maine
    Yes!!! Thanks for the encouragement. I have suspected the draft because the boiler does smoke when I reload with wood. The boiler is attached to an 8' masonry flu.
    I live in a 2 story cape and the boiler is in the basement. That means the chimney is about 25-30' high. It was cleaned by a sweep recently so that is not the problem...
    I have looked thru the chimney section and I am not sure what the best bet is in terms of increasing my draft. I have emailed J Kennard at Buderus to see if I can get the proper riddling tool. I spoke to a tech years ago with no luck... Guess I will check draft increasing gizmos more seriously now and I will look through the sections you suggested. Anyway, thanks again for the reply. It gives me hope.
  9. Corie

    Corie Minister of Fire

    Joined:
    Nov 18, 2005
    Messages:
    2,430
    Loc:
    Halifax, VA
    1) Open mouth

    2) Insert foot


    OOPS!! Sorry for the misinformation.
  10. webbie

    webbie Seasoned Moderator Staff Member

    Joined:
    Nov 17, 2005
    Messages:
    12,382
    Loc:
    Western Mass.
    At first glance the chimney would seem tall enough.....but mine was that tall also, and it didn't work well. In terms of your chimney, try the following

    make certain interior black pipe has as few bends as possible and furnace cement between section.
    Boiler should have a barometric damper on pipe.
    Bends should be changed to 45 from 90 if possible for best smoke flow
    Pipe should be sealed well where it goes into wall
    check chimney clean out door for tightness
    If chimney extends below where pipe enters, try sealing that with a wad of insulation.


    Also, you can:
    1. Line chimney with ss pipe
    2. Extend Chimney (I'll give you a great deal on an extendaflue)
    3. Use chimney top fan..
  11. elkimmeg

    elkimmeg Guest

    Adding to craigs list it would help if you provided a description of your current setup with connector piping is the chimney located on an outside wall. This is the only appliance using this flue line? Describe the existing chimney configurations other flues and ash cleanouts . Many times the ash cleanouts are just doors below your flues with a wide open area underneath meaning the other assh doors can leak other flues provide air to adjacent flues Lots of things to consider we need more info
  12. HarryBack

    HarryBack New Member

    Joined:
    Dec 27, 2005
    Messages:
    990
    Loc:
    Western Massachusetts
    LOL! me too, Corie, except I still stand by coal burning stoves having shakable grates being better than non-shakeable, generally speaking!
  13. Corie

    Corie Minister of Fire

    Joined:
    Nov 18, 2005
    Messages:
    2,430
    Loc:
    Halifax, VA
    Yeah I agree. I'm not familiar with coal furnaces and these alleged "wet grates". However as far as stoves go, I wouldn't consider one without shakeable grates and the one I am building does in fact have shakeable grates, 6 to be exact.
  14. webbie

    webbie Seasoned Moderator Staff Member

    Joined:
    Nov 17, 2005
    Messages:
    12,382
    Loc:
    Western Mass.
    There are good shaking grates and there are bad ones.

    The best type I have used are the ones that were originally in Colebrookdale stoves and were copied by VC for the new Vigilant. They alternate (every other grate goes a different direction) front to back and do not "wave" or "rock". They also have small round tabs sticking up into the coal bed.
  15. HarryBack

    HarryBack New Member

    Joined:
    Dec 27, 2005
    Messages:
    990
    Loc:
    Western Massachusetts
    give me ANY shakeable grate over a non-shakeable for coal anyday.

    Ever see the old Warm Morning Grates? Now THAT was a great grate! :cheese:
  16. webbie

    webbie Seasoned Moderator Staff Member

    Joined:
    Nov 17, 2005
    Messages:
    12,382
    Loc:
    Western Mass.
    They aren't "alleged" - they actually exist!

    And, in the case of boilers, consider this - the grates add a tremendous amount of square inches of heating surface (the grates are round and also have fins and tabs on them). A boiler with "dry" grates is wasting a lot of that heat as downward radiation which ends up getting lost one way or another if the boiler does not have enough heat exchange area.

    Here is the model I used to sell:

    Coal Boiler

    If you look closely at the pic on the left, you will see the very thick area at the bottom which are the grates with water running through them. You can also see baffles up in the firebox which are what the grates also look like. That is A LOT OF HEAT EXCHANGE AREA and will outperform most any steel boiler due to this.

    You can poke or knife it in the little "smile" at the bottom of the front grate.
  17. Corie

    Corie Minister of Fire

    Joined:
    Nov 18, 2005
    Messages:
    2,430
    Loc:
    Halifax, VA
    hehe thanks Craig! Learn something knew every day :)

    And I agree about the Vigilant system. When I start designing the casting for my own grates if I ever make it that far, they will absolutely be of the same type.
Thread Status:
Not open for further replies.

Share This Page