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<TITLE>VAV airhandler with face and bypass dampers</TITLE>
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<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">Does anyone have any advice on</FONT></SPAN><SPAN LANG="en-us"> <FONT FACE="Calibri">modeling</FONT></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"></FONT></SPAN><SPAN LANG="en-us"> <FONT FACE="Calibri">a VAV air handler with face and bypass dampers? Essentially I have a set of dampers with a heating coil before the cooling coil.</FONT></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"> When in heating only the discharge air temp</FONT></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri">erature is reset based between 55F and 65F. In cooling the DAT is between 55F and 59F.</FONT></SPAN><SPAN LANG="en-us"> <FONT FACE="Calibri">Chillers and CHW loop is set to demand.</FONT></SPAN><SPAN LANG="en-us"> </SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">I had tried</FONT></SPAN><SPAN LANG="en-us"> <FONT FACE="Calibri">modeling</FONT></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"> a preheat coil</FONT></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"> to simulate the heating coil being before the cooling coil</FONT></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri">, but the results were not as expected.</FONT></SPAN><SPAN LANG="en-us"> <FONT FACE="Calibri">When I looked at the hourly reports I found the following: </FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">1) </FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="Calibri">Space temperatures for the unit were above the</FONT></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"> heating set-point and below the cooling set-point. Yet, the cooling coil was activated. I have a suspicion that this is due to equest turning on cooling coil if there is any chance a space may need coo</FONT></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri">ling but have been unable to confirm.</FONT></SPAN><SPAN LANG="en-us"> <FONT FACE="Calibri">In addition, the given RAT, MAT, DAT t</FONT></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri">emperatures due not make sense. For example: </FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"> RAT=67F</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"> <FONT FACE="Calibri">MAT=55F</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"> <FONT FACE="Calibri">DAT (off cooling coil)=48F with cooling coil ru</FONT></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri">nning and OAT below 32F.</FONT></SPAN><SPAN LANG="en-us"> </SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">2) </FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="Calibri">The %OA is constant even at night. Cfm/</FONT></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri">per has been specified at the zone level.</FONT></SPAN><SPAN LANG="en-us"> <FONT FACE="Calibri">Should it be at the system level?</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">Any help would be greatly appreciated.</FONT></SPAN><SPAN LANG="en-us"></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"></SPAN></P>
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<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=5 FACE="Calibri">Andy Szczepaniak</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Calibri">Mechanical Engineer</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><B></B></SPAN><B><SPAN LANG="en-us"></SPAN></B><B><SPAN LANG="en-us"><FONT FACE="Calibri">MICHAELS ENGINEERING INC</FONT></SPAN></B></P>
<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri">400 Main St. Ste 200</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">La Crosse, WI 54601</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">Direct: (608) 785-3323</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">Main: (608) 785-1900</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">Fax: (608) 784-2270</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><B></B></SPAN><B><SPAN LANG="en-us"></SPAN></B><B><SPAN LANG="en-us"><FONT FACE="Calibri">AAS@MichaelsEngineering.com</FONT></SPAN></B></P>
<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"><A HREF="http://www.michaelsengineering.com">http://www.michaelsengineering.com</A></FONT></SPAN></P>
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