Hi All,<br><br>Thanks for your comments and responses. The system is VAV. I've tried all kinds of controls to model mandatory cooling of supply air to 55 and then reheat to 67. Bottom line is that I can't make eQuest do it. If 55 F air is required to cool a space, it won't reheat to 67, and if 67 is all that's needed, it won't first cool to 55. Mandatory cooling and reheat simply doesn't make any sense to the program. It doesn't make much sense in reality either, except that it is the least expensive way to provide 55 F air to some zones and 67 to others. 67 is required for some zones as the air will be blown directly on people, and 55 is extremely uncomfortable for humans, thus the required reheat.<br>
<br>The system is VAV, which complicates things as the volume of air, and thus the energy needed to condition it, is constantly changing. I have finally decided to go with the spreadsheet method to develop a rough estimate, as this is all that is needed in this case. However, this foray has led me to desire some additonal controls capabilitys for airside systems in eQuest.<br>
<br>Actually, I've thought that it might make sense for some cases to run eQuest to output hourly zone loads, Then you could input these loads into another program that could handle more complex heating and cooling delivery systems, not necessarily do this for all projects, just the extra-special ones. Does anyone know if trnsys can handle this type of thing? Are there any other programs that can handle this type of thing?<br>
<br>Thanks again,<br><br>--<br>Karen<br><br><br><br><div class="gmail_quote">On Tue, Nov 25, 2008 at 8:46 AM, Doug Maddox <span dir="ltr"><<a href="mailto:DougM@twgi.com">DougM@twgi.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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<p><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">Karen,</span></font></p>
<p><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">Is this VAV or constant volume? </span></font></p>
<p><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">If it's constant volume, and if the
system is actually able to meet loads with 67 F supply air, then I would think
you could set the MIN-SUPPLY-T to 55 F and COOL-CONTROL = CONSTANT, and it
should reheat to at least 67 F for all hours.</span></font></p>
<p><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;"><br>
If it's VAV, I'm not so sure. Possibly you could tweak the
MIN-CFM-RATIO or use MIN-CFM-SCHEDULE so that the zones generally want 67 F air
to meet cooling loads. This could be tricky since loads will vary, but
maybe you could get it close.</span></font></p>
<p><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">Good luck,</span></font></p>
<p><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">Doug Maddox</span></font></p><div class="Ih2E3d">
<p><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
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<p><b><font size="2" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma; font-weight: bold;">From:</span></font></b><font size="2" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma;">
<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">equest-users-bounces@lists.onebuilding.org</a> [mailto:<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">equest-users-bounces@lists.onebuilding.org</a>]
<b><span style="font-weight: bold;">On Behalf Of </span></b>Karen Walkerman<br>
<b><span style="font-weight: bold;">Sent:</span></b> Monday, November 24, 2008
4:43 PM<br>
<b><span style="font-weight: bold;">To:</span></b>
<a href="mailto:equest-users@lists.onebuilding.org" target="_blank">equest-users@lists.onebuilding.org</a><br>
<b><span style="font-weight: bold;">Subject:</span></b> [Equest-users] reheat in
eQuest</span></font></p>
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<p><font size="3" face="Times New Roman"><span style="font-size: 12pt;"> </span></font></p>
</div><p><font size="3" face="Times New Roman"><span style="font-size: 12pt;">Hi All,<div><div></div><div class="Wj3C7c"><br>
<br>
I'm modeling a building that uses a single air handler to serve multiple
zones. One set of zones ("A zones") require 55F supply air
temperature for cooling, the other set of zones ("B zones") require
67F supply air temperature. This can be accomplished either by cooling
all the air to 55, then reheating the air sent to "B zones" to
67. The other way to accomplish this is to heat some air to 55, supply 55
to "A zones" and mix some return air with the 55F air to create 67F
air for "B zones."<br>
<br>
The question is: can eQuest do such a thing? I have loosely approximated
the second option by modeling two different air handlers for the "A"
and "B" zones, one having a MIN-SUPPLY-T of 55 and the other of
67. Is there a better way to model this?<br>
<br>
How can I model the first option? If I use a reheat coil, it only comes
on if the spaces need heat, and thus doesn't accurately model the constant
reheat required to heat the supply air from 55 to 67.<br>
<br>
Any input/ideas are really appreciated.<br>
<br>
Thanks,<br>
<br>
--<br>
Karen Walkerman</div></div></span></font></p>
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