Brian,<br><br>Hard to say without knowing more e.g. building type, internal loads, etc., but in general, although Paul may disagree, that's pretty high. I do not disagree with using that methodology, as long as the cfm/sf stays within reason. <br>
<br>If I were you I would start with looking at the internal loads, like w/sf for equipment and process, etc. If they can be raised or lowered reasonable, do so. The rule is, in general, that they be the same in both cases, so make sure you pick the changes up in your other model. Also look at your temperatures entered in the zones/systems and associated schedules.<br>
<br>Otherwise, you can always send the .pd2 and .inp files to us.<br><br>Carol<br><br><div class="gmail_quote">On Fri, Apr 8, 2011 at 10:00 AM, Brian Goldsmith <span dir="ltr"><<a href="mailto:Brian.Goldsmith@atce.com">Brian.Goldsmith@atce.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div link="blue" vlink="purple" lang="EN-US">
<div>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span style="font-size:10.0pt;font-family:Arial;color:navy">So if I force the cfm/sqft to 2, it brings
the unmet load hours down to about 80, which is good. But of course the fan
energy spikes. Each zone has its own unit. Is it good practice to force the
cfm/sqft? Especially considering what this does to the fan energy?</span></font></p><div class="im">
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span style="font-size:10.0pt;font-family:Arial;color:navy"> </span></font></p>
<div>
<p class="MsoNormal" style="margin-bottom:3.0pt"><b><i><font color="#333399" face="Times New Roman" size="3"><span style="font-size:12.0pt;color:#333399;letter-spacing:1.2pt;font-weight:bold;font-style:italic">Brian
Goldsmith</span></font></i></b><font color="navy"><span style="color:navy"></span></font></p>
<p class="MsoNormal"><b><b><font color="green" face="Gill Sans MT" size="1"><span style="font-size:7.5pt;font-family:"Gill Sans MT";color:green;letter-spacing:1.0pt;font-weight:normal"><a href="mailto:Brian.Goldsmith@atce.com" title="blocked::mailto:Brian.Goldsmith@atce.com" target="_blank">Brian.Goldsmith@atce.com</a></span></font></b></b><span><u><font color="blue"></font></u></span></p>
<p class="MsoNormal"><b><b><font color="green" face="Gill Sans MT" size="1"><span style="font-size:7.5pt;font-family:"Gill Sans MT";color:green;letter-spacing:1.0pt;font-weight:normal">direct</span></font></b></b><font color="green" face="Gill Sans MT" size="1"><span style="font-size:7.5pt;font-family:"Gill Sans MT";color:green;letter-spacing:1.0pt"> <a href="tel:408.487.1217" value="+14084871217" target="_blank">408.487.1217</a></span></font></p>
</div>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span style="font-size:10.0pt;font-family:Arial;color:navy"> </span></font></p>
</div><div>
<div class="MsoNormal" style="text-align:center" align="center"><font face="Times New Roman" size="3"><span style="font-size:12.0pt">
<hr align="center" size="2" width="100%">
</span></font></div>
<p class="MsoNormal"><b><font face="Tahoma" size="2"><span style="font-size:10.0pt;font-family:Tahoma;font-weight:bold">From:</span></font></b><font face="Tahoma" size="2"><span style="font-size:10.0pt;font-family:Tahoma"> Joe Fleming
[mailto:<a href="mailto:joe@thespinnakergroupinc.com" target="_blank">joe@thespinnakergroupinc.com</a>] <br>
<b><span style="font-weight:bold">Sent:</span></b> Thursday, April 07, 2011
1:55 PM</span></font></p><div><div><font face="Tahoma" size="2"></font></div><div class="h5"><font face="Tahoma" size="2"><br>
<b><span style="font-weight:bold">To:</span></b> Brian Goldsmith;
<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> RE: [Equest-users] Heat
Pump Heating Undersized</font></div></div><p></p>
</div><div><div></div><div class="h5">
<p class="MsoNormal"><font face="Times New Roman" size="3"><span style="font-size:12.0pt"> </span></font></p>
<p class="MsoNormal"><font color="#1f497d" face="Calibri" size="2"><span style="font-size:11.0pt;font-family:Calibri;color:#1F497D">Check the minimum
flow ratio and the minimum design flow cfm/sqft for the trouble zones.
</span></font></p>
<p class="MsoNormal"><font color="#1f497d" face="Calibri" size="2"><span style="font-size:11.0pt;font-family:Calibri;color:#1F497D">In the VAV system
equest distributes a percentage of the supply airflow to each zone. But
cfm/sqft is a priority in the hierarchy and if you bump it up for the trouble <u>zones</u>
you will get higher cooling and heating airflows at your given SAT. The
energy you provide to the room is equal to CFM*(Tsupply-Troom)*</span></font><font color="#1f497d" face="Calibri" size="2"><span style="font-size:10.0pt;font-family:Calibri;color:#1F497D">(1.085 or another conversion factor depending on units
and air density). </span></font><font color="#1f497d" face="Calibri" size="2"><span style="font-size:11.0pt;font-family:Calibri;color:#1F497D">So
if your schedules and equipment are set up correctly you should override the
equest defaults for airflows or SAT.</span></font></p>
<p class="MsoNormal"><font color="#1f497d" face="Calibri" size="2"><span style="font-size:11.0pt;font-family:Calibri;color:#1F497D"> </span></font></p>
<div>
<p class="MsoNormal"><font color="#52b230" face="Trebuchet MS" size="2"><span style="font-size:11.0pt;font-family:"Trebuchet MS";color:#52B230"> </span></font></p>
<p class="MsoNormal"><font color="#52b230" face="Trebuchet MS" size="2"><span style="font-size:10.0pt;font-family:"Trebuchet MS";color:#52B230">Joe Fleming,
E.I., LEED AP BD+C, BEMP</span></font></p>
<p class="MsoNormal"><font color="#52b230" face="Trebuchet MS" size="2"><span style="font-size:10.0pt;font-family:"Trebuchet MS";color:#52B230">Commissioning
Agent</span></font></p>
<p class="MsoNormal"><font color="#52b230" face="Trebuchet MS" size="2"><span style="font-size:10.0pt;font-family:"Trebuchet MS";color:#52B230"><a href="tel:561-602-3132" value="+15616023132" target="_blank">561-602-3132</a></span></font></p>
<p class="MsoNormal"><font color="#52b230" face="Trebuchet MS" size="2"><span style="font-size:10.0pt;font-family:"Trebuchet MS";color:#52B230"> </span></font></p>
<p class="MsoNormal"><font color="#52b230" face="Trebuchet MS" size="2"><span style="font-size:10.0pt;font-family:"Trebuchet MS";color:#52B230">The Spinnaker
Group</span></font></p>
<p class="MsoNormal"><b><u><font color="#52b230" face="Trebuchet MS" size="2"><span style="font-size:11.0pt;font-family:"Trebuchet MS";color:#52B230;font-weight:bold"><a href="http://www.thespinnakergroupinc.com" target="_blank"><font color="#52b230"><span style="color:#52B230">www.thespinnakergroupinc.com</span></font></a></span></font></u></b></p>
</div>
<p class="MsoNormal"><font color="#1f497d" face="Calibri" size="2"><span style="font-size:11.0pt;font-family:Calibri;color:#1F497D"> </span></font></p>
<div>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><font face="Tahoma" size="2"><span style="font-size:10.0pt;font-family:Tahoma;font-weight:bold">From:</span></font></b><font face="Tahoma" size="2"><span style="font-size:10.0pt;font-family:Tahoma"> Brian Goldsmith
[mailto:<a href="mailto:Brian.Goldsmith@atce.com" target="_blank">Brian.Goldsmith@atce.com</a>] <br>
<b><span style="font-weight:bold">Sent:</span></b> Thursday, April 07, 2011
4:36 PM<br>
<b><span style="font-weight:bold">To:</span></b> Joe Fleming;
<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> RE: [Equest-users] Heat
Pump Heating Undersized</span></font></p>
</div>
</div>
<p class="MsoNormal"><font face="Times New Roman" size="3"><span style="font-size:12.0pt"> </span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span style="font-size:10.0pt;font-family:Arial;color:navy">Ya I looked at all that, seemed to be
fine. It seems like whenever I change my system from single zone package to
variable air volume this problem comes up. I just changed the system type and
left everything else the same.</span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span style="font-size:10.0pt;font-family:Arial;color:navy"> </span></font></p>
<div>
<p class="MsoNormal" style="margin-bottom:3.0pt"><b><i><font color="#333399" face="Times New Roman" size="3"><span style="font-size:12.0pt;color:#333399;letter-spacing:1.2pt;font-weight:bold;font-style:italic">Brian
Goldsmith</span></font></i></b><font color="navy"><span style="color:navy"></span></font></p>
<p class="MsoNormal"><b><b><font color="green" face="Gill Sans MT" size="1"><span style="font-size:7.5pt;font-family:"Gill Sans MT";color:green;letter-spacing:1.0pt;font-weight:normal"><a href="mailto:Brian.Goldsmith@atce.com" title="blocked::mailto:Brian.Goldsmith@atce.com" target="_blank">Brian.Goldsmith@atce.com</a></span></font></b></b><span><u><font color="blue"></font></u></span></p>
<p class="MsoNormal"><b><b><font color="green" face="Gill Sans MT" size="1"><span style="font-size:7.5pt;font-family:"Gill Sans MT";color:green;letter-spacing:1.0pt;font-weight:normal">direct</span></font></b></b><font color="green" face="Gill Sans MT" size="1"><span style="font-size:7.5pt;font-family:"Gill Sans MT";color:green;letter-spacing:1.0pt"> <a href="tel:408.487.1217" value="+14084871217" target="_blank">408.487.1217</a></span></font></p>
</div>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span style="font-size:10.0pt;font-family:Arial;color:navy"> </span></font></p>
<div>
<div class="MsoNormal" style="text-align:center" align="center"><font face="Times New Roman" size="3"><span style="font-size:12.0pt">
<hr align="center" size="2" width="100%">
</span></font></div>
<p class="MsoNormal"><b><font face="Tahoma" size="2"><span style="font-size:10.0pt;font-family:Tahoma;font-weight:bold">From:</span></font></b><font face="Tahoma" size="2"><span style="font-size:10.0pt;font-family:Tahoma"> Joe Fleming
[mailto:<a href="mailto:joe@thespinnakergroupinc.com" target="_blank">joe@thespinnakergroupinc.com</a>] <br>
<b><span style="font-weight:bold">Sent:</span></b> Thursday, April 07, 2011
12:14 PM<br>
<b><span style="font-weight:bold">To:</span></b> Brian Goldsmith;
<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> RE: [Equest-users] Heat
Pump Heating Undersized</span></font></p>
</div>
<p class="MsoNormal"><font face="Times New Roman" size="3"><span style="font-size:12.0pt"> </span></font></p>
<p class="MsoNormal"><font color="#1f497d" face="Calibri" size="2"><span style="font-size:11.0pt;font-family:Calibri;color:#1F497D">Usually scheduling
(fan, available heating and t-stat don’t coincide every hour of every day),
airflow (too low), SAT (too low), or multiple zones on one unit.</span></font></p>
<p class="MsoNormal"><font color="#1f497d" face="Calibri" size="2"><span style="font-size:11.0pt;font-family:Calibri;color:#1F497D">Usually…</span></font><b><u><font color="#52b230" face="Trebuchet MS" size="2"><span style="font-size:11.0pt;font-family:"Trebuchet MS";color:#52B230;font-weight:bold"></span></font></u></b></p>
<p class="MsoNormal"><font color="#1f497d" face="Calibri" size="2"><span style="font-size:11.0pt;font-family:Calibri;color:#1F497D"> </span></font></p>
<div>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><font face="Tahoma" size="2"><span style="font-size:10.0pt;font-family:Tahoma;font-weight:bold">From:</span></font></b><font face="Tahoma" size="2"><span style="font-size:10.0pt;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>Brian Goldsmith<br>
<b><span style="font-weight:bold">Sent:</span></b> Thursday, April 07, 2011
2:24 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] Heat Pump
Heating Undersized</span></font></p>
</div>
</div>
<p class="MsoNormal"><font face="Times New Roman" size="3"><span style="font-size:12.0pt"> </span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;font-family:Arial">I’m having trouble with the heating in my heat pump. I
modeled a Packaged VAV (PVAVS) with HEAT-SOURCE= Heat Pump and ZONE-HEAT-SOURCE=
Not Installed. Set HEAT-SET-T to 120F, DESIGN-HEAT-T to 70F, and did not
specify auxiliary heat. I get the message that my zone has insufficient heating
capability. Looking at SS-A, is says the maximum heating load is only -10.1
KBTU/HR. Looking at SS-P, the report says my heating capacity is -47.8 KBTU/HR.
So why do I have 563 underheated hours? Does it have something to do with the
system type? I tried ZONE-HEAT-SOURCE= Heat pump and tried HEAT-SIZING-RATIO=
5, just to see if either one would do anything, although I didn’t really expect
them to. Also tried electric supplemental heat, which comes out to -31.715
KBTU/HR. My design supply flow is 1913 CFM, and the outside air flow is 252
CFM. The design supply flow is the same for both the heating and cooling
performance summaries. Should this be the case? Thanks for any help.</span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;font-family:Arial"> </span></font></p>
<p class="MsoNormal"><i><b><i><font color="#333399" face="Times New Roman" size="3"><span style="font-size:12.0pt;color:#333399;letter-spacing:1.2pt;font-weight:bold">Brian
Goldsmith, LEED</span></font></i></b></i><b><sup><font color="#333399" face="Gill Sans MT" size="2"><span style="font-size:10.0pt;font-family:"Gill Sans MT";color:#333399;letter-spacing:1.2pt;font-weight:bold">®</span></font></sup><i><i><font color="#333399" face="Times New Roman"><span style="color:#333399;letter-spacing:1.2pt"> AP</span></font></i></i></b></p>
<p class="MsoNormal"><font color="#333399" face="Times New Roman" size="2"><span style="font-size:11.0pt;color:#333399">Design Engineer</span></font></p>
<p class="MsoNormal"><font color="green" face="Gill Sans MT" size="1"><span style="font-size:7.5pt;font-family:"Gill Sans MT";color:green;letter-spacing:1.0pt"><img src="" border="0" height="30" width="149"></span></font></p>
<p class="MsoNormal"><font color="green" face="Gill Sans MT" size="1"><span style="font-size:7.5pt;font-family:"Gill Sans MT";color:green;letter-spacing:1.0pt">97 E. Brokaw Road</span></font><font color="green" face="Gill Sans MT" size="1"><span style="font-size:7.5pt;font-family:"Gill Sans MT";color:green;letter-spacing:1.0pt">, No 300</span></font></p>
<p class="MsoNormal"><font color="green" face="Gill Sans MT" size="1"><span style="font-size:7.5pt;font-family:"Gill Sans MT";color:green;letter-spacing:1.0pt">San Jose</span></font><font color="green" face="Gill Sans MT" size="1"><span style="font-size:7.5pt;font-family:"Gill Sans MT";color:green;letter-spacing:1.0pt">, CA 95112</span></font><font color="green" face="Gill Sans MT" size="1"><span style="font-size:7.5pt;font-family:"Gill Sans MT";color:green;letter-spacing:1.0pt"></span></font></p>
<p class="MsoNormal"><b><b><font color="green" face="Gill Sans MT" size="1"><span style="font-size:7.5pt;font-family:"Gill Sans MT";color:green;letter-spacing:1.0pt;font-weight:normal">main </span></font></b></b><font color="green" face="Gill Sans MT" size="1"><span style="font-size:7.5pt;font-family:"Gill Sans MT";color:green;letter-spacing:1.0pt"><a href="tel:408.487.1200" value="+14084871200" target="_blank">408.487.1200</a></span></font></p>
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