Centrally Produced Steam for Domestic Hot Water

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Hi All

I am trying to put together a model for a building on a University
campus that uses centrally generated steam to create domestic hot water.
As there is no direct way to model this using eQuest, I was hoping
somebody might have some guidance for me.

My initial idea was to use a steam meter connected directly to the DHW
loop, and modify the efficiency to account for the heat exchanger, but
this doesn't seem to work as there are no options for adding a storage
tank to the loop in this setup. There may be other issues as well that
I'm not thinking of.

The trial I'm working on now is to use an electric DW boiler in
combination with a steam turbine generator. The steam turbine generator
would be connected to the district steam hot water loop, and the
electricity generated would be put to a new, dedicated electric meter
for this specific purpose, which is the assigned to the electric DW
heater. The waste heat of the turbine would not be set up to just
dissipate rather than be used. The issue I'm having with this, is that
I can't figure out how to size the kW of the steam turbine generator,
and I can't let eQuest autosize it. I'm basically creating an imaginary
electrical load. Would I just convert the BTU/hr of the actual unit
into kW, and set the EIR of the generator to reflect the efficiency of
the HX and other losses in the actual system? Or is this method
blatantly wrong for some reason I'm overlooking?

Thanks all for you help!!

Adam A. Gonthier

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I am actually having the same problem. When you put a steam meter onto
the DHW loop, it still charges (in my case) natural gas. There is no
option to setup the DHW heater with any fuel except electricity or
natural gas. I was hoping not to go through converting steam into
electricity. Is it possible to take the MBTU from the BEPS report and
convert it into steam somehow?

Amanda E. Martz, EIT, LEED AP

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