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Posted by HeatPro on October 14, 2006 at 13:05:26:
In Reply to: Re: Steam Boiler Replacement posted by Newbie Doobie on October 14, 2006 at 12:07:37:
: I looked at the boiler specifications but I don't see mention of BTU outputs, though I probably just don't know how to read these things.
: Is BTU output the same as DOE Heating Capacity MBH?
Yes and No. (How else can 'experts' get paid more?)
It is confusing and I'd bet that half the plumbers don't really know the difference.
Input is the amount of heat in the fuel that enters the burner in the hour.
DOE output is what heat comes out of the boiler in the hour. (Less because the boiler isn't 100% efficient, some heat goes out the chimney and sides of the boiler.)
IBR rating is the DOE output less 25% because you have to heat up the boiler, pipes, and radiators BEFORE you get heat out of the radiators. (That 25% might not be enough in a system with extra large and long pipe runs.)
Thus the OSB-4-125 can input 1.25 gph for a 175,000 input, puts out 145,000 for DOE, and has an IBR rating of 109,000 that could handle 454 square feet of Equivalent Direct Radiation (EDR) radiator size.
The Peerless ECT-05 has 1.75 or 2 gph, 212 or 240M steam DOE output, 160-180,000 IBR for 660-750 sq ft of EDR.
As the Peerless ratings stop at 63-06 with 287,000 input, I have no idea why anyone would specify such a wide range of boilers for one house.
Again, it seems there is no rhyme nor reason to the selection method for your house.