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the wall

That 42,400 SF corresponds to 10,200,000 BTUH while 15,057,000 input at say, 80% efficiency (probably high) nets 12,045,600 output which corresponds to 50,190 SF. Keep in mind that the burner may be <i>rated</i> for the 15 MMBH but is possibly set up for less.

A current project I am involved with has a 1956-1957 vintage Fitzgibbons with an under-fired burner by a similar percentage. And yes, we are about to replace it! (The whole thing.)

I cannot tell you what the ratings are, whether net or gross. What we did in our case I will recommend to you:

Calculate a heat loss and take a radiation/emitter survey. Compare them. If steam, size by EDR. If water, by BTUH. It is more work up-front but yields a responsible selection.

My $0.02



  • Jim Dowiat
    Jim Dowiat Member Posts: 2
    Fitzgibbons boiler rating

    I'm to replace some Fitzgibbons model DM-425 boilers (circa 1958-60). In an old copy from their catalog the boiler has an EDR rating-SBI of 42,400 sq. ft. and a net rating-SBI of 35,000 sq. ft. Can it be assumed that the EDR rating is the gross output rating? I've never seen gross output presented with an EDR rating.
    This bothers me because the burners (15-20 years old) are sized for an input of 15,057,000 BTUH. They seem WAY oversized.
  • Jim Dowiat
    Jim Dowiat Member Posts: 2

    Thanks Brad, I'm sure you are right, the burner output is reduced. If the burner had been undersized by a similar percentage like yours, that would have really thrown me.
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