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Fire box insulation

adasilva Member Posts: 144
So had my boiler serviced last week and the back of my fire box (combustion chamber?) has insulation on the back side that has fallen forward. This keeps the flame from heating the deeper sections of the boiler itself. Thought on how this would affect the efficiency of the boiler? I know that the last season wasn't too cold but my bill was quite high and I believe that it most likely is due to having this kaowool board hindering the flame and it takes longer to heat up? Thoughts?


  • motoguy128
    motoguy128 Member Posts: 394
    IF it’s altering the flow of flue gases, then it’s most likely impacting efficiency and worst would be causing uneven heating of the sections, which can at worst, cause thermal stress and over time metal fatigue.

    IS this a 3 pass boiler with a power burner? IF it’s atmospheric, then combustion might be impacted as well and if it falls further, it could land on the burners and cause rollout.
  • adasilva
    adasilva Member Posts: 144
    @motoguy128 I agree with you about the efficiency, I also have them scheduled to come out and re do the insulation because it is stifling the heating on the third section. I believe by 3 pass boiler you mean 3 sections? If so then yes it is (New Yorker CLS 3P). It has a Carlin EZ heat gas conversion burner which I was told that has a fairly long flame for the short boiler that I have. Not sure of the pertinence of that statement, but it is what it is. The service guy did a combustion test and it passed with good results as well. Prefer to keep it in good working order!
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    If your chamber is failing (crumbling, falling forward), it needs to be replaced. The flame is now impinging on it, inefficient, dirty flame making soot and CO. The boiler will soot up in a short time.
    Should've been replaced at time of servicing. They had the front of the boiler off, correct? Or they should have for proper cleaning.
    The biggest cause of target wall failure is improper, aggressive brushing during a cleaning. The second in impingement.
  • nde
    nde Member Posts: 86
    edited November 2020
    I too had a short/wide wet base boiler that was converted to natural gas burner....and indeed the gas burner had a long flame compared to the firebox design. Within 18 months the firebox collapsed in the back. If you can get the front door off (mine was not swing and was a real bear to remove without breaking cast in bolts) then rebuilding it is a must. I got another 6 years out of the firebox after rebuilding but the fact was the flame was too long for that firebox and would come back towards the blast tube. Has to replace the blast tube once as it had cracked from flame roll back (riello burner).

    The contractor I used for conversion is the one who rebuilt chamber, etc. He stated that he no longer recommends conversions unless the chamber is deep enough for the flame of the conversion burner.

    Having said that I replaced the boiler this fall and used the sgo gold wet base with conversion burner (vs atmospheric). The longer firebox design in the WM pairs well with a conversion burner. I was borderline on EDR between the sgo4 and sgo5 but went with the 5 b/c the extra section gives a bit more length The conversion burner can be fired at the desired EDR, so firing closer to the sgo4 input of 170000 btus but with longer chamber. The combustion test post install was 84% efficiency with this setup.

    So far a nice setup and the contractor has used the gold for years with good results for those wanting wet base steamer on gas connections.
  • adasilva
    adasilva Member Posts: 144
    @STEVEusaPA @nde   They did not have the front open but it does have a swing out door.  I was told that they had to order the insulation and it would be in with in the week.  As for the aggressive brushing it very well could have been the last time it was serviced but they guy who pointed it out didnt want to get into it too much as to avoid more damage.  He did make the statement that it burns really clean by looking at the sections where he was brushing.
  • Steamhead
    Steamhead Member Posts: 16,727
    If the conversion burner is a Carlin EZ-Gas, this burner can be fitted with several different diffusers (heads) that will alter the flame pattern. I'd use the 9-slot diffuser in that boiler, since it duplicates the flame pattern of a flame-retention oil burner.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service