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Improve Old Boiler Efficiency?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by scottinkn, Jan 1, 2013.

  1. scottinkn

    scottinkn Member

    Joined:
    Oct 12, 2008
    Messages:
    47
    Loc:
    Monson, MA
    Hello,

    I needed to clean my flue & boiler tubes, and as I was mindlessly brushing the tubes, I wondered if there were any things that I could do to improve my boilers efficiency, when I hook up my tank, later on this week.

    SO

    Assuming well seasoned & dry wood :

    1 - Wood size - what would my optimum wood size be? would real small be better? 2x4 size?

    2 - Tubes - my boiler tubes go straight up & out the flue & no damper (just barometric damper)
    Could I space a thick baffle plate (divide chamber) over the tubes to slow down flue gas or recirc somehow?
    (I noticed that the tubes at the 4 corners clog with ash)

    3 - Pressurize it - remove barometric damper and add 2nd combustion fan for more air.

    Any Suggestions?
    DSC03406.JPG DSC03407.JPG DSC03408.JPG

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  2. BoilerMan

    BoilerMan Minister of Fire

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    Northern Maine
    Forgive me, but what kind of boiler is that? A conventional boiler with firetubes?

    I had a NewYorker and welded in a baffel and secondary stailess air tubes. My stack temps lowered but it still smoked a lot. Your setup is not lacking for surface area as the NY was so I'd saw some kind of seconadry air above the fire and preheated as well. You need to burn the volitile gasses (smoke) to really improve a wood burning appliance's efficiency.

    TS
  3. scottinkn

    scottinkn Member

    Joined:
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    Loc:
    Monson, MA
    I have a New Yorker WC 130. So if I could recirc some flue gas it would be good?
  4. BoilerMan

    BoilerMan Minister of Fire

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    Are those pics of the WC? Mine looked nothing like that. Just a water-jacked box design.

    TS
  5. Hansson

    Hansson Feeling the Heat

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    Sweden,Leksand
    Whats the flu gas temp?
    Maybe u can try to make turbulators for the tubes.
    U can make them of corrugated iron plates.

    Attached Files:

  6. jebatty

    jebatty Minister of Fire

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    Regular brushing of the tubes would help - estimate an efficiency increase of 2-3% for each 100F drop in flue temperature. I brush the tubes in my boiler about 2 x month. Turbulators also would help, likely a 2-3% increase in efficiency.
  7. scottinkn

    scottinkn Member

    Joined:
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    Loc:
    Monson, MA
    I don't have flue temp gauge, I just ordered one.

    Turbulators - if they just slow/mix the flue gas , I could probably just hang some chains in the tubes...
    (Since I will be cleaning the tubes more frequently.)
  8. Nofossil

    Nofossil Moderator Emeritus

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    One avenue to pursue is the ideal fire. Should be hot with plenty of air so that it's burning 'flat out' with lots of flames and virtually no smoke.

    Big logs smoldering for long periods of time is not what you want, but wood that's too small with too much surface area will need more air than your inlet can supply. There's a happy medium in there somewhere. Once you have a good coal bed, you can add a couple pieces at a time and get decent results. Visible smoke is a clue that you're not at the optimum operating point.

    It's an art more than a science.
    Taylor Sutherland and scottinkn like this.
  9. scottinkn

    scottinkn Member

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    Thanks Nofossil! I like that idea! It is the simple things that make a big difference....
  10. maple1

    maple1 Minister of Fire

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    If you just ordered a new flue temp guage, be aware of the difference in readings between a magnetic type & a probe type. I've got both side by side & the magnetic always reads 100c less than the probe, at full burn. If you've got hot stack temps, I'd try some chains in the tubes as mentioned - that would be the easiest. And also as mentioned, burning procedures play a big part. Reducing idling time is key - which may require more frequent smaller fires. Whenever the damper is closed, efficiency goes south in a hurry - and the dirty increases. Unfortunately though, there is only so much efficiency to be gained in an appliance that has water cooling a fire almost directly through the steel that separates them.
  11. scottinkn

    scottinkn Member

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    I ordered probe type, I guess that will be the first step to see where I can make gains with this.

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