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<P><FONT SIZE=2 FACE="Courier New">Hi All,</FONT>
<BR><FONT SIZE=2 FACE="Courier New">I am trying to model a residential unit served by a Fan coil unit (FCU). It has a separate outside air fan and exhaust fan operating 24/7. The fan coil unit is available to operate for all hours but should operate intermittently depending on the room load.</FONT></P>
<P><FONT SIZE=2 FACE="Courier New">I tried modeling this by selecting a 4-pipe FCU and specified the exhaust and outside air at the thermal zone level. I made the FCU to operate intermittently by making the “Fan on mode” to be intermittent. By doing this, what I observed in the hourly report was:</FONT></P>
<P><FONT SIZE=2 FACE="Courier New">1. FCU unit cycles intermittently as intended.</FONT>
<BR><FONT SIZE=2 FACE="Courier New">2. Exhaust fan operates continuously (24/7) (with the specified cfm) as intended.</FONT>
<BR><FONT SIZE=2 FACE="Courier New">3. However, the outside air cycles per the FCU. </FONT>
<BR><FONT SIZE=2 FACE="Courier New">•If the FCU is off, then OA cfm is zero</FONT>
<BR><FONT SIZE=2 FACE="Courier New">•If FCU supply air cfm < the OSA cfm specified at the zone level, then hourly OSA cfm matches the FCU supply air cfm •If FCU supply air cfm > the OSA cfm specified at the zone level, then hourly OSA cfm matches the cfm specified at the zone level.</FONT></P>
<P><FONT SIZE=2 FACE="Courier New">As mentioned before, I want my outside air to operate continuously with constant flow-rate. Can anyone suggest me a way to model this system?</FONT></P>
<P><FONT SIZE=2 FACE="Courier New">Thanks in advance for your help!</FONT>
<BR><FONT SIZE=2 FACE="Courier New">Regards,</FONT>
<BR><FONT SIZE=2 FACE="Courier New">Yuvaraj</FONT>
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<P><FONT SIZE=2 FACE="Arial">_</FONT><FONT COLOR="#000000" SIZE=2 FACE="Arial">_____________________________________________</FONT>
<BR><FONT COLOR="#000000" SIZE=2 FACE="Arial">Yuvaraj Saravanan, PE</FONT>
<BR><FONT COLOR="#000000" SIZE=2 FACE="Arial">Engineer</FONT>
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<P><FONT COLOR="#000000" SIZE=2 FACE="Arial">Arup </FONT>
<BR><FONT COLOR="#000000" SIZE=2 FACE="Arial">12777 West Jefferson Boulevard Suite 200</FONT>
<BR><FONT COLOR="#000000" SIZE=2 FACE="Arial">Los Angeles CA 90066</FONT>
<BR><FONT COLOR="#000000" SIZE=1 FACE="Arial">tel: 1 310 578 4400</FONT>
<BR><FONT COLOR="#000000" SIZE=1 FACE="Arial">dir: 1 310 578 4521</FONT>
<BR><FONT COLOR="#000000" SIZE=1 FACE="Arial">fax: 1 310 577 7011</FONT>
<BR><FONT COLOR="#000000" SIZE=1 FACE="Arial">internal freecall: x20521</FONT>
<BR><FONT COLOR="#000000" SIZE=1 FACE="Arial">yuvaraj.saravanan@arup.com</FONT><BR>
<A HREF="file://www.arup.com"><U></U><U><FONT COLOR="#0000FF" SIZE=2 FACE="Arial">www.arup.com</FONT></U></A>
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