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Ultra Boiler efficiency

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icy78
icy78 Member Posts: 404
in THE MAIN WALL
Hey all, havent been around in a while, and hope everyone's well.
  Got a question on rating conditions on Weil McClain ultra boilers. I thought I'd read a couple years ago that the efficiency rating was, in part, based on an EWT of 60 degrees F.
      Well I can't find that spec anywhere. 
Anyone know what the rating points are?
  I see the ratings in the manual but not specifics.
   Thanks!

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  • Ironman
    Ironman Member Posts: 7,376
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    The EPA requires that all hot water boiler AFUE ratings be done with 120* return water and 140* supply water. The brand makes no difference. Like MPG ratings for a car.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    HVACNUTicy78knotgrumpy
  • icy78
    icy78 Member Posts: 404
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    Ironman said:
    The EPA requires that all hot water boiler AFUE ratings be done with 120* return water and 140* supply water. The brand makes no difference. Like MPG ratings for a car.

    Hmm. So that's true for condensing and non-condensing then.
         I ment to type 80F RWT not 60 but still that's far below 120.
       Wondering if the 120 is from back before condensing boilers were a thing?
       Maybe the 80F was European.  Dont they size for 130-140 SWT and 40-50 emitter delta ?


  • Jamie Hall
    Jamie Hall Member Posts: 23,280
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    I think the point to remember is sort of a twist on @Ironman 's comment: the AFUE rating is a means of comparing various designs. In order to make the comparison valid, it is done under a tightly prescribed set of conditions. One can say that under those specific conditions with the specified installation and perfectly tuned a new boiler will have such and such an efficiency. Beyond that, no. Changing the conditions will change the efficiency -- obviously -- but it won't change them in the same way for different designs. Even relatively minor changes in installation have an effect. And, as we know, setting the combustion off -- even by a relatively small amount -- can have major changes on efficiency.

    What is it for,then? As I say, mostly to provide a comparison point -- and also to demonstrate compliance with various legislative or regulatory diktats. No more, and no less.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    icy78Ironman
  • icy78
    icy78 Member Posts: 404
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    While waiting in the Chiropractors office today, I was reading the Ultra manual  and I found the  testing is based on AHRI BTS-2000.
        It states that for condensing boilers, EWT is to be 80° F plus or min 5°F and LWT to be 180.
       Interesting that's a 100 degree delta and the Ultra allows 58 delta max. ( before faulting) 
  • icy78
    icy78 Member Posts: 404
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    icy78 said:
    While waiting in the Chiropractors office today, I was reading the Ultra manual  and I found the  testing is based on AHRI BTS-2000.
        It states that for condensing boilers, EWT is to be 80° F plus or min 5°F and LWT to be 180.
       Interesting that's a 100 degree delta and the Ultra allows 58 delta max. ( before faulting) 

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