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<DIV><FONT face=Arial size=2><SPAN class=875500421-06082008>I've been getting
some warnings in a model I'm currently working on, and I haven't been able to
find a way to fix them.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=875500421-06082008></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=875500421-06082008>The warnings are as
follows:</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=875500421-06082008></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN
class=875500421-06082008> **WARNING**********************************************************************<BR>
PREHEAT/HEATING-CAPACITY in SYSTEM M AHU-26
(VAV)
<BR> is
too low to provide the requested supply temperature
for<BR>
the calculated mixed air temperature using total ZONE
loads<BR>
(on LS-A/B) and SYSTEM design parameters, plus outside
air<BR>
conditions (on LS-C), and specified capacities & air
flows.<BR>
Requested temperature is 55.00 calculated is
10.37<BR>
Check HEATING-CAPACITY, HEAT-SET-T, PRE-HEAT-T,
MAX-SUPPLY-T,<BR>
DESIGN-HEAT-T, and ZONE loads for consistency.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=875500421-06082008>AHU-26 is a PIU
system (series boxes). Zone outside airflow is set up at 20 CFM / person,
the # of people is accurate, and the system is set up to size the minimum OA
based on the sum of the zone OA.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=875500421-06082008></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=875500421-06082008>I can't figure out
what's going on....it almost seems like the system is not returning any air, and
is at 100% OA. But my OA is set to a fixed fraction, and inputing an
arbitrary supply CFM doesn't change the mixed air temp warning at all (still
10.37).</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=875500421-06082008></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=875500421-06082008>I know it's hard to
diagnose a problem without being able to open the file (I'm happy to send
someone the .inp and .pd2 files), but has anyone run into this problem
before?</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=875500421-06082008></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN
class=875500421-06082008>Thanks!</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV align=left>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; mso-layout-grid-align: none"
align=left><B><SPAN style="COLOR: teal; FONT-FAMILY: Arial">GHT
Limited<BR></SPAN></B><?xml:namespace prefix = st1 ns =
"urn:schemas-microsoft-com:office:smarttags" /><st1:PersonName><B><SPAN
style="FONT-SIZE: 11pt; FONT-FAMILY: Arial">James
Hansen</SPAN></B></st1:PersonName><B><SPAN
style="FONT-SIZE: 11pt; FONT-FAMILY: Arial">, <FONT size=2>PE, LEED
AP</FONT></SPAN></B></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; mso-layout-grid-align: none"
align=left><B><SPAN style="FONT-SIZE: 11pt; FONT-FAMILY: Arial"><FONT
size=2>Senior Associate</FONT></SPAN></B></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; mso-layout-grid-align: none"
align=left><SPAN style="FONT-SIZE: 11pt; FONT-FAMILY: Arial"><FONT size=1>1010
N. Glebe Rd, Suite 200</FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; mso-layout-grid-align: none"
align=left><SPAN style="FONT-SIZE: 11pt; FONT-FAMILY: Arial"><FONT
size=1>Arlington, VA 22201-4749</FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; mso-layout-grid-align: none"
align=left><SPAN style="FONT-SIZE: 11pt; FONT-FAMILY: Arial"><FONT
size=1>703-338-5754 (Direct)</FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; mso-layout-grid-align: none"
align=left><SPAN style="FONT-SIZE: 11pt; FONT-FAMILY: Arial"><FONT
size=1>703-243-1200 (Office)</FONT></SPAN></P>
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align=left><SPAN style="FONT-SIZE: 11pt; FONT-FAMILY: Arial"><FONT
size=1>703-276-1376 (Fax)</FONT></SPAN></P>
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align=left><SPAN style="FONT-SIZE: 11pt; FONT-FAMILY: Arial"><A
href="http://www.ghtltd.com/"><FONT
size=2>www.ghtltd.com</FONT></A></SPAN></P></DIV>
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