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RE: [EnergyPlus_Support] Re: Boiler efficiency according to ASHRAE (e.g. according to CFR)

Dear forum,

I have not followed this thread closely, but I doubt that it’s a simple matter to model a specific boiler’s part-load efficiency without a lot of data.  I think some of the condensing boiler catalogs have enough data to make a decent curve, but I don’t know if it’s common.

For a Baseline boiler, I agree with Francesco – it’s not worth spending a lot of time refining the efficiency of a “fictitious” piece of equipment.  My approach so far is to use the ASHRAE 90.1 required efficiency and also to use a curve that reflects some degradation at low loads.  After I read the AHRI test procedure (and after I wake up the next morning J) I’ll see if that makes sense.

Thanks for the link Francesco!


From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of FrancescoP
Sent: Friday, August 10, 2012 10:02 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: Boiler efficiency according to ASHRAE (e.g. according to CFR)



Thank you Javed,
it seems that the test conditions are indicated here:
During the test the "outlet water temperature" has to be maintained at "180°F" (i.e. 82°C). Unsurprising, 82°C is also the hot-water supply temperature for the baseline model according to G3.1.3.3 (ASHRAE 90.1-2007).

Modeling the thermal efficiency of the baseline model has constant would be a good idea? It doesn't correspond to a real boiler, but to a reference boiler.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Javed Iqbal <eee.javed@...> wrote:
> Hi,
> You can find 10 CFR Part 431 boiler test procedure here. look at page no.
> 461 .
> http://www.gpo.gov/fdsys/pkg/CFR-2011-title10-vol3/pdf/CFR-2011-title10-vol3-part431.pdf
> Check this for Boiler efficiency. ..
> http://www.designbuilder.co.uk/helpv3/Content/Boilers.htm
> On Fri, Aug 10, 2012 at 5:00 PM, FrancescoP <direzionecontraria@...>wrote:
> > **
> >
> >
> > I'm developing a baseline model for LEED certification. The boiler
> > efficiency has to respect Table 6.8.1F of ASHRAE 90.1:2007. The thermal
> > efficiency Et shall be equal to 80% according to the test procedure 10 CGR
> > Part 431. I'm modeling the boiler using the object Boiler:HotWater. I
> > imposed the "nominal thermal efficiency" equal to 0,8 but what about the
> > "normalized boiler efficiency curve"? Any suggestion, please?
> > Do you have any information regarding the conditions of the test procedure
> > 10 CFR Part 431?
> > With Regards
> > Francesco Passerini
> >
> >
> >
> --
> Javed Iqbal, LEED AP, CEA
> Energy Analyst


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