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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>If the chiller you are using is the “well-water-to-water
HP” type (CHILLER:HEAT-PUMP), I have successfully been able to run
a simulation with this chiller connected to a CHW loop. However, it was
only connected to a loop with a process chilled water load, and not connected
to coils.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>The loop-to-loop HP (CHILLER:LOOP-TO-LOOP-HP), which I believe
Karen is referring to, is intended to be attached to both a HW and CHW
circulation loops. As I understand the DOE-2 help, there is an important
difference between these chillers in that the LOOP-TO-LOOP-HP chiller allows
for exchange of heat between the HW and CHW circulation loops, where as the
HEAT-PUMP chiller only moves heat to-and-from the CW loop (LAKE/WELL
type). You can connect multiple HEAT-PUMP or LOOP-TO-LOOP chillers to a
single LAKE/WELL loop and heat exchanger, so you could potentially have one
chiller supply your HW and one chiller supply CHW by adjusting the controls of
the 2-PIPE loop. Having them connected to the same CW loop, the total CW
load should be equal to the sum of the energy pulled out by the chiller in
heating, the energy put in by the chiller in cooling, and the loop pump heat
(plus loop thermal losses if simulated). However, this is somewhat
irrelevant because no matter what the CW loop return temperature is, the LAKE/WELL
loop and heat exchanger will always provide the scheduled supply temperature (or
by default, the hourly ground temperature in the weather file).<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>To get around this, we have developed an approach that takes the
building loads from the LAKE/WELL loop and applies them to a DOE-2 well-field model,
and in turn, takes the resulting well-field temperatures for use in the
building hourly simulation. It requires post-processing and some
iteration, but I think this type of approach could be as good as we can do with
the existing tool.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Any other approaches out there?</span><span style='font-size:
11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Tahoma","sans-serif";
color:#1F497D'>David Reddy<o:p></o:p></span></b></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Tahoma","sans-serif";
color:#1F497D'>Madison Engineering, PS<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Tahoma","sans-serif";
color:#1F497D'>444 NE Ravenna Blvd, Suite 406<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Tahoma","sans-serif";
color:#1F497D'>Seattle, WA 98115<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Tahoma","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
equest-users-bounces@lists.onebuilding.org
[mailto:equest-users-bounces@lists.onebuilding.org] <b>On Behalf Of </b>Karen
Walkerman<br>
<b>Sent:</b> Wednesday, February 04, 2009 8:58 AM<br>
<b>To:</b> Tim Dion<br>
<b>Cc:</b> equest-users@lists.onebuilding.org<br>
<b>Subject:</b> Re: [Equest-users] Simultaneous Heating/Cooling<o:p></o:p></span></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'>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.<br>
<br>
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!<br>
<br>
--<br>
Karen<br>
<br>
<o:p></o:p></p>
<div>
<p class=MsoNormal>On Wed, Feb 4, 2009 at 11:38 AM, Tim Dion <<a
href="mailto:TimD@hargis.biz">TimD@hargis.biz</a>> wrote:<o:p></o:p></p>
<div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>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.</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
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<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>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.</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>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. </span><o:p></o:p></p>
</div>
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<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>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. </span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Tim
Dion, LEED® AP <br>
Mechanical<br>
<b><span style='color:navy'>HARGIS ENGINEERS</span></b> <br>
600 Stewart Street <br>
Suite 1000 <br>
Seattle, WA 98101 <br>
<a href="http://www.hargis.biz/" target="_blank"><span style='color:gray;
text-decoration:none'>www.hargis.biz</span></a> <br>
<br>
<b><span style='color:gray'>d | </span></b><span style='color:gray'>206.859.5391</span>
<br>
<b><span style='color:gray'>o | </span></b><span style='color:gray'>206.448.3376
</span><br>
<b><span style='color:gray'> f | </span></b><span
style='color:gray'>206.448.4450</span> </span><o:p></o:p></p>
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<p class=MsoNormal> <o:p></o:p></p>
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<p class=MsoNormal style='margin-bottom:12.0pt'><br>
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