Clarity boiler sizing

Discussion in 'Boiler Forum' started by netmouse, Oct 8, 2013.

  1. netmouse

    netmouse Member

    Aug 7, 2012
    In sizing, how big is "too big" and how small is "too small". Assuming everything else is perfect (ha!)

    Example, vendor EDRs for a new steam boiler range from 260 to 285. The 285 is my own with a form from here (reduced from 291 due to gaps in the chart and I took the next higher figure). I did not factor in the pipes, I am told manufacturer sizes factor that in to their sq ft.

    Boiler A (Burnham) is 271 sq ft and AFUE 82.0 (next size up is 358, next size down is 158). Boiler B (Peerless) is 308 sq ft and AFUE 82.6 (next size up is 383, next down is 233).

    One steam guy said the numbers between boiler choices of 271 or 308 are so close it does not matter which I choose. There is a fudge factor and either can be adjusted 10% or 15%.

    Given that a manufacturer's next boiler size up or down is quite a difference, I'd have to think the manufacture would be able to accommodate any EDR by picking the closest and making adjustments. Right, or?
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