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[EnergyPlus_Support] Re: Manually sizing baseboards and plant loops

An object Pump:ConstantSpeed (Flow Rate: autosize) is used for the HW
loop. The object Boiler:HotWater has a variable flow mode. I am not sure
if this variable flow inflicts the HW loop or is just an internal aspect
of the boiler.

The model is run in E+ v.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad
<RRaustad@...> wrote:
> Are you using a variable-speed or constant-speed pump?
> avdbree wrote:
> >
> > I am investigating an existing building. The idea is to add
> > and keep the existing baseboards. So, the (new) heating can work
> > a lower supply temperature.
> >
> > When I autosize maximum (water) flow rates and/or UA-factors in the
> > objects ZoneHVAC:Baseboard:Convective:Water, Boiler:HotWater and
> > PlantLoop, I get a Delta T of the HW-loop up to 15 °K (which is
> >
> > Then I set myself maximum water flow rates for the baseboards (based
> > on the maximum heating rates from a simulation), while keeping the
> > flows of Boiler:HotWater and PlantLoop autosized. Delta T of the
> > HW-loop dropped to about 3 °K (which is to small). The results
for the
> > Zone Mean Air Temperatures and Baseboard Heating Rates are still
> > (and similar to the autosized situation). Apparently, the flow in
> > HW-loop is quite big now and most of the flow during most of the
> > is going through the bypass on the demand-side of the HW-loop. This
> > increases the return temperature and decreases Delta T. A small
> > T is not economic.
> >
> > The occuring maximum loop flow in the HW-loop is exactly the sum of
> > all maximum water flows of all the baseboards (as specified in the
> > object ZoneHVAC:Baseboard:Convective:Water). So, I tried to set
> > a lower Maximum Loop Flow Rate of the Plant:Loop (in order to lower
> > the bypassed flow and thus increasing Delta T). I choose the maximum
> > sum of all the baseboards water flows AT ANY GIVEN MOMENT. This
> > maximum is -- in my case-- less then half of the sum of all
> > (non-simultaneously) maximum water flows. And, by the way, about
> > as much as for the completely autosized situation.
> >
> > But even when I manually set the Maximum Loop Flow Rate of the
> > Plant:Loop, the occuring flow in the HW-loop is still the (much
> > higher) sum of all (non-simultaneously) maximum flows of all
> >
> > Did I forgot to change another object too or is this a bug?
> >
> > PS. I tried to attach the idf-file but could not find the way to do
> >
> >
> --
> Richard A. Raustad
> Senior Research Engineer
> Florida Solar Energy Center
> University of Central Florida
> 1679 Clearlake Road
> Cocoa, FL  32922-5703
> Phone:   (321) 638-1454
> Fax:     (321) 638-1439 or 1010
> Visit our web site at: http://www.fsec.ucf.edu
> UCF - From Promise to Prominence: Celebrating 40 Years


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