[Equest-users] Simultaneous Heating/Cooling

[Karen Walkerman]

Why are you using a separate lake/well loop and heat pump for the chilled
water loop?  You should be able to have the same piece of machinery attached
to both a chilled water loop and a hot water loop.  This way heat is
transferred from one loop to the other when there are simultaneous loads.
The ground loop is only used when there is net heating or cooling needed.

My beef with this system is that you can only use a loop type of lake/well
using a constant condenser water temperature.  This is usually not the case
with ground loops, unless you are circulating water from an underground
reservoir!

--
Karen


On Wed, Feb 4, 2009 at 11:38 AM, Tim Dion <TimD at hargis.biz> wrote:

>  I'm modeling a ground loop heat exchanger to provide condenser water to a
> large water-to-water heat pump which will be capable of providing
> simultaneous heating and chilled water to AHU coils in the building. The
> Water-to-water Heat Pump being designed around is similar to that
> manufactured by Multistack, Heat-Harvester, Climacool, etc.
>
> I've successfully created a 2-pipe water loop with a water-to-water heat
> pump that gets its' condenser water from a ground loop heat exchanger
> (lake/well). When assigned to Fan Coils in the building this system appears
> to work just fine. However, no simultaneous heating/cooling capability.
>
> So, I've now added a chilled water loop with a second water-to-water heat
> pump that gets its' condenser water from a seperate ground loop heat
> exchanger. I then assigned the cooling coils to the chilled water loop and
> the heating coils to the 2-pipe water loop. Trouble is I get the error that
> reads, "the chilled water loop has no load". If I manage to get this error
> to go away then my zones have 5,000 + hours of unmet heating loads.
>
> I've been searching the archives and I see that this has come up several
> times but with no real solution other than "it should be able to be done".
> I'm posting the question again in hopes that someone who has successfully
> modeled this system can point the rest of us in the right direction. This
> type of system is coming up more and more (I have 4 projects considering
> them now) and as we strive toward greater building efficiency we are going
> to HAVE to be able to successfully model these system types.
>
> Tim Dion, LEED(R) AP
> Mechanical
> *HARGIS ENGINEERS*
> 600 Stewart Street
> Suite 1000
> Seattle, WA 98101
> www.hargis.biz
>
> *d | *206.859.5391
> *o | *206.448.3376
> * f | *206.448.4450
>
>
> _______________________________________________
> Equest-users mailing list
> http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
> To unsubscribe from this mailing list send  a blank message to
> EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20090204/ff5a9e97/attachment-0001.htm>