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boiler insulation

Oddly in a way and compared to European boilers, US boilers tend to have 1.0 to 1.5 inch fiberglass on their boilers. European high mass boilers, invariably hot water, have 3 to 4 inches thickness. So here, with steam, we have a lot less with more losses.

I suppose if you have any insulation now it probably fills the jacket. I cannot see a real advantage to adding more insulation the outside of the metal jacket because it will likely obscure clean-out ports or combustion air and interfere with servicing or will be torn asunder with the first service call.

If the outer jacket temperature is much over 90 degrees, I would investigate what might be underneath the insulation. If the jacket temperature is that or below, I see no thermal advantage really.

Do you have an IR thermometer or accurate way to take a quick surface temperature reading?

My $0.02



  • jason_35
    jason_35 Member Posts: 1
    boiler insulation

    I have an old American Standard A34M oil fired steam boiler
    What are your thoughts on insulating the boiler itself with fiberglass to decrease the standby losses ??

    Great sit been reading posts here for a long time!!
  • jason_36
    jason_36 Member Posts: 1

    there is some insulations under the jacket
    temp in some areas is on the order of 120 F
    when i have time i will tear it apart and add more
    can i use normal fiberglass that i would use in a wall or something else? what i was thinking of using is 2'X4' fiberglass ceiling panels with the plastic removed on the outside of the steel jacket
  • Brad White_184
    Brad White_184 Member Posts: 135
    I think that

    the use of face-less batt insulation makes sense. I suppose some compression but not too much, will be OK. Ideally a rigid fiberglass board would work and be neater but would not conform to the boiler itself. It would "fit the jacket" well, though. By the time you locate that and order it, you could be enjoying some savings.

    Yes, I think that a 120F jacket temperature says that you have room for improvement.

    Our industry standard is 95 degrees in a 75 degree ambient, for personnel protection as a criteria. Enough safety (no one would be burned at 95F) but not so great on efficiency. Still, one has to choose your fights.
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