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PB 105 burnpot bubble issue update

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by wil lanfear, Oct 6, 2012.

  1. wil lanfear

    wil lanfear Feeling the Heat

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    The new burnpot with the fins DIDNOT resolve the issue. About 6 weeks ago I had a group of three including a engineer from Harman along with the local Harman dealer visit checking out my boiler. After checking everything one of the harman reps (not the engineer) thought the reason for the bubble was not enough air passing through the burnpot. I wasn't to impressed with the engineer when he mentioned that " nothing jumped out at him " as reasoning why this bubble occurs. The rep adjusted the draft (white screw) on the controller for the combustion blower so it gets full voltage for maximim RPM all the time, so much for this being used as a draft adjustment per owners manual. It had been adjusted to spec from the owners manual. I should be receiving another burnpot with a different grade stainless (more heat resistant) burning surface plus the burning surface will be a heavier guage in a couple weeks to try. I have noticed that the bubble that had started to form on the present burnpot, it hasn't got any worse since the tech adjusted the controller for maximum RPM. Could it be not enough air going through the burnpot created by adjusting the draft to spec, I'm thinking it is, the reason that some owners of the PB 105's and PF100's are not having the burnpot bubble issue.​

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  2. exoilburner

    exoilburner Feeling the Heat

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    Interesting observation. Makes sense. The PB105 and PF100 folks on here have been trying to figure that one out for quite a while.

    Looking forward to hearing how their next burnpot design works in your rig. Kind of funny; you told them to try a hi-temp steel over a year ago.
  3. Alain S. Prevost

    Alain S. Prevost Member

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    I wonder if it is the brand of pellets....the resin they use during the production process...or even softwood with the sap....or even any pellet mixed with bark as a binder have different levels of acids and products we don't know the effects it has directly introduced on metals at high temp. also sugars and starches from specific trees will have a factor in its chemical composition as well. I am unsure of the specifics through the production process, how they bleach the product or remove anything at all while keeping high BTU content.

    An incorrect, abnormal or higher/lower acid/alkaline balance on any stainless steel would be catastrophic, especially with increased tempuratures....
    Also the oxides and hydrogen/nitrogen generated from burning the pellets, while introducing moist air (salts) (from your outside air kit, or even your basement air) will have water vapors flashing to superheated temperatures on the stainless and may cause premature failure of any/all metals regardless of stainless steel's supreme metallurgy.
    Probably have to change the burnpot to a corrosion resistant alloy...see the chart below with credits to an offshore drilling supply/specialty company dealing with super alloys for nasty corrosive and sour gas wells...

    Just a thought.


    1.gif
  4. wil lanfear

    wil lanfear Feeling the Heat

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    I've burned several brands of pellets over past 5+ years, the bubble forms with whatever pellet that is used. I've already mentioned to the Harman folks to try using a alloy with a high nickel content to manufacture the burnpots. It hasn't happened, maybe it would be to costly, I don't know.
  5. wil lanfear

    wil lanfear Feeling the Heat

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    The photos are of the newly designed burnpot for the pb105 and pf100 which Harman has been testing for the past 2 months in an effort to resolve the burnpot bubble issue. I have it installed, time will tell. My dealer told me that this will be the burnpot used in both new central heating units manufactured from now on.The burning surface is 3/16 stainless plus notice the fact that the burning surface is not solid welded to the sides to allow for expansion.

    [​IMG]
    http://i153.photobucket.com/albums/s216/vtreloader/DSC00037.jpg[/IMG
    [IMG]http://i153.photobucket.com/albums/s216/vtreloader/DSC00036.jpg
    [​IMG]
  6. Lousyweather

    Lousyweather Guest

    interesting ventilated sides as well....
  7. wil lanfear

    wil lanfear Feeling the Heat

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    Here are a couple more photos.
    [​IMG]
    [​IMG]
  8. exoilburner

    exoilburner Feeling the Heat

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    Great update Wil, thanks. This looks promising.

    Is this a prototype or a production burn-pot? I am wondering about mounting the electric igniter for the older model furnaces. Should be two screw holes located above the burn pot cleanout plate. I did not see holes or knock-outs for them in your pictures. Did you hear if an electric igniter could be installed in this new pot?
    .
    [​IMG]
  9. wil lanfear

    wil lanfear Feeling the Heat

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    My understanding from my dealer, this design burnpot is going to be the burnpot installed in all new pb105's and pf100's. The burnpot that I have doesn't have any holes or knockouts to mount the finned igniter. It looks like all that would be needed to do is to layout and drill these holes, wouldn't be hard to do.
  10. Lousyweather

    Lousyweather Guest

    I beleive subsequent models used the pressure ignition system
  11. iceguy4

    iceguy4 Minister of Fire

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    Well I just picked up my new boiler today11/29/12 and I am impressed. my burnpot has no holes on the sides and i took off the plate and no igniter to be seen! It looks like it is hidden on the right side behind the burn pot. I'll take some pictures as soon as its installed. Kinda an easy install...took out wooden stairs in bilco doors and lowered into basement with backhoe. plan to have it up by saturday noon-ish. vent done, plumbing tie-ins done ...all that is needed is 10 0r 15 foot of pipe and the electric..:p
  12. Ejectr

    Ejectr Minister of Fire

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    I'm on my second season with my PF100 and so far, no issues with the burn pot (knock on pellets). My draft control has been wide open since day 1 because that is where I got the closest results to spec.
  13. stephenmoore

    stephenmoore Member

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    Wil are you using the new ignition system or the old one in your 105 ?
  14. Former Farmer

    Former Farmer Feeling the Heat

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    I believe that Wil had upgraded his boiler from the old finned igniter to the new pressurized igniter system.

    I have the old finned igniter and have had to replace my burnpot once each season. I had to replace it 3 weeks ago, so this heating season, it may have to be replaced twice.
  15. wil lanfear

    wil lanfear Feeling the Heat

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    I have the new pressure ignition that was installed to stop the burnpot bubble, it didn't happen. My advice, take it for whatever its worth, if you have had the burnpot bubble issue, adjust the draft so the combustion blower runs at full speed all the time plus when you have to replace the burnpot, ask your dealer to get the newest designed burnpot that I've posted the photo of.
  16. iceguy4

    iceguy4 Minister of Fire

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    How do you adjust the draft? I checked it with my oil boiler draft checker and it pegs it so its WAY higher then .25 in water...
  17. wil lanfear

    wil lanfear Feeling the Heat

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    It's the small white adustment screw on the controller, my advice to you is, leave it alone per the three Harman reps that came to inspect why I was having the burnpot bubble issue. The controller from the factory is adjusted for maximum RPM of the combustion blower. Mine had been adjusted to spec but one of the Harman reps felt that not enough air was passing through the burnpot which in turn caused the burnpot bubble.
    iceguy4 likes this.
  18. iceguy4

    iceguy4 Minister of Fire

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    Will do (leave it alone)and thanks...I WILL be adding a outside air intake as this sucker moves some air.. Is that gonna cool down my boiler big time?? what is the general census on outside air...My house is FAR..VERY FAR from tight.;ex
  19. ScotL

    ScotL Feeling the Heat

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    I've tried outside air on my PB105. It's quite a long run for me (it's in the cellar) so it's constricting the airflow a little bit. I necked it up to a 4" line right at the connector on the boiler and that helped to eliminate the helicopter sound - mostly. It does help for those times when I don't have the free time to clean it for a really long time and it makes that nice little "kaboom" on startup. It keeps the smoke from the concussion from blowing back into the cellar.
    Has anyone found something that works well for brushing out the heat exchanger tubes in the PB105? I'm using a stovepipe brush now but it's too big.
  20. iceguy4

    iceguy4 Minister of Fire

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    I'm going to put a 6" pipe around my pellet chimney and feed the outside air around it to pre-heat the outsise air. when I get it put together I will post pictures. I'm still waiting for the kit
  21. SmokeyTheBear

    SmokeyTheBear Minister of Fire

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    You might want to visit a brew shop and see what they have in the way of brushes and then there are gun cleaning kits that might come in handy.
    iceguy4 likes this.
  22. iceguy4

    iceguy4 Minister of Fire

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    Go to a plumbing supply place and pick up a brush for cleaning an oil boiler. they will have an assortment.
    SmokeyTheBear likes this.
  23. wil lanfear

    wil lanfear Feeling the Heat

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    I just finished my weekly cleaning of my boiler this morning,it has been a couple months now since the newly designed burnpot was installed. This is the longest period of time without the bubble starting to form since the boiler was installed nearly 6 years ago, this burnpot hasn't developed any bubble, it looks the same as when it was installed. I believe that it's a combination of two things, the draft adjustment that was adjusted so the combustion blower is running at maximum RPM when a fire is in the burnpot plus the design of the new burnpot. I'm thinking that for those that own the pf100's or the pb105's having "the burnpot bubble issue", talk to your dealer, asking if these burnpots are available, hopefully under the warranty.
    Mr._Graybeard and SmokeyTheBear like this.
  24. SmokeyTheBear

    SmokeyTheBear Minister of Fire

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    Sounds encouraging Wil.
  25. Mr._Graybeard

    Mr._Graybeard Member

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    Thanks very much for the update, Wil. When my dealer comes over to service my boiler at the end of the season I'll have him look at the little bump that has formed in the burnpot. Bet he'll OK a warranty replacement with the new design.

    I appreciate your dedication to this thread. I might not have even considered it an issue if not for your diligence.

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