[Bldg-sim] Steam trap leaks

[Julien Marrec]

Hi Rohini,

I had been wondering the same thing: how to quantify these losses. I did
some literature review and only found values such as the FEMP Study
(15%-20%).

I started using my own methodology based on Grashof's equation of steam
discharge, which was later reused by the NYSERDA Multifamily Performance
Program in their simulation guideline so I'm guessing it wasn't that stupid.

My two cents are that failed-closed traps are noticed more (no heat), so I
usually assume the average opening of the failed trap is above 50%.

You'll find in attachment a calc note to see how I use that. Note that for
this specific projects I actually knew for a fact that 17% of the traps
were busted since they were all tested and replaced. Otherwise, you can
assume 10% of traps get busted per year, and cap it out at 40%. Also, I
wouldn't go higher than 15 or 20% in losses (per FEMP)

I'll welcome any constructive feedback on my methodology, or better yet a
smarter and more precise way to calculate those losses.

And like David said, I would also usually include these losses as a load.

Enjoy your weekend folks!

Best,
Julien
--
Julien Marrec, EBCP, BPI MFBA
Energy & Sustainability Engineer
T: +33 6 95 14 42 13
www.julienmarrec.com

DoYouBuzz : www.doyoubuzz.com/julien-marrec_1
LinkedIn (fr) : www.linkedin.com/in/julienmarrec/fr
LinkedIn (en) : www.linkedin.com/in/julienmarrec


2014-05-09 21:13 GMT+02:00 David Eldridge <DEldridge at grummanbutkus.com>:

> Depending on the program the steam losses could be entered as a load...in
> that way it could be tracked separately as an end-use.
>
> This approach might be easier to manage if the part of the system with the
> leaky traps might be scheduled off at times. (In which case you'd be
> scheduling the boiler efficiency instead.)
>
> DSE Mobile
>
> > On May 9, 2014, at 12:51 PM, "R B" <slv3sat at gmail.com> wrote:
> >
> > Hi All,
> > Here is an end-of-week question - I normally model steam trap leaks by
> derating the boiler efficiency. I was wondering is anyone had a
> different/better way of modelling it. Also, when the audit says lots of
> steam traps leaking, I assume 15-20% losses (based on a FEMP document).
> What are typical assumptions that others do?
> > Thanks and have a nice weekend.
> > -Rohini
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