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[EnergyPlus_Support] Re: Two AirloopHVAC serving the same zones



can one put a fan on a bypass branch? can one bypass an entire AHU?

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Karen Walkerman <kwalkerman@...> wrote:
>
> Hi Martin,
> 
> This approach is used in the file DDAutoSize.idf to simulate a dual-duct
> system.  This model has the supply fan before the splitter.  I don't know
> how well it would work to have two supply fans, one on each main branch...
>  It's always a little dangerous trying to make software do something it
> wasn't designed to do...  Good luck!
> 
> --
> Karen
> 
> On Tue, Jul 12, 2011 at 1:53 PM, Jim Dirkes <jim@...
> > wrote:
> 
> >
> >
> > I think I may have known that what Karen suggests is possible, but never
> > actually considered that approach.  Great suggestion!
> >
> >
> >
> > *The Building Performance Team
> > **James V. Dirkes II, P.E., BEMP , LEED AP
> > *1631 Acacia Drive NW
> > Grand Rapids, MI 49504
> > 616 450 8653
> >
> >
> >
> > *From:* EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:
> > EnergyPlus_Support@xxxxxxxxxxxxxxx] *On Behalf Of *Martin Gogov
> > *Sent:* Tuesday, July 12, 2011 12:13 PM
> > *To:* EnergyPlus_Support@xxxxxxxxxxxxxxx
> > *Subject:* Re: [EnergyPlus_Support] Two AirloopHVAC serving the same zones
> >
> >
> >
> >
> >
> > Thank you so much for this idea, Karen! I didn't know that!
> >
> > I think this scenario might work if it is possible to assign different fan
> > types and ADUs to each main branch of the Air loop since I need constant air
> > volume for the ventilation and variable air volume for the cooling.
> >
> > Could I kindly ask you to give me a short IDF example how to set two
> > branches on the same loop? I'm struggling to find one in the example files..
> >
> > Thanks!
> > Martin
> >
> > On Tue, Jul 12, 2011 at 5:34 PM, Karen Walkerman <kwalkerman@...>
> > wrote:
> >
> >
> >
> > Is there any way to add the packaged VAV with Reheat to your existing
> > outdoor air system airloop?  You can't have two airloops, but the airloop
> > itself can have more than one main supply branch, and unlike a plantloop can
> > have more than one outlet node and zone distribution.  You could set up one
> > branch of the airloop with the as-designed outdoor air system serving your
> > terminal boxes in the zones, and another branch of the airloop (with a
> > separate exit node) serving a different terminal reheat box.
> >
> >
> >
> > Good luck!
> >
> >
> >
> > --
> >
> > Karen
> >
> >
> >
> > On Tue, Jul 12, 2011 at 11:10 AM, Martin Gogov <mgogov@...> wrote:
> >
> >
> >
> > Dear EnergyPlus experts,
> >
> > I'm preparing a model for LEED for a building with multiple zones which has
> > ventilation system for fresh air and a separate heating system.
> >
> > By design, there's no cooling system in the building.
> >
> > I've used a single AirLoopHVAC to model the system for fresh air since it
> > serves more than one zones.
> >
> > I think that the ERV and Outdoor Air Unit systems are not applicable for my
> > case since this would be a major difference with the project docs.
> >
> > Since by design the building doesn't have a cooling system, it's necessary
> > that in the Proposed and Baseline cooling systems are the same: a Packaged
> > VAV with Reheat.
> >
> > And here is the problem!
> >
> > In order to model a Packaged VAV with Reheat, I need to use one more
> > AirLoopHVAC, correct?
> > This shouldn't work since each zone has only a single Return Air Node and
> > in the zones which have a ventilation system for fresh air, this Return Air
> > Node is already used by its AirLoopHVAC!
> >
> > And I don't know how to handle Two AirloopHVAC serving the same zones...
> >
> > I've already spent a few days on this problem but yet I cannot find of a
> > suitable solution.
> > Any ideas on how to proceed greatly appreciated!
> >
> > Thank you very much,
> > Martin
> >
> >
> >
> >
> >  
> >
>




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