I have found the same thing as Maria, increasing the flow increases unmet heating. Another place to check is the min flow - reducing min flow also reduces unmet heating.<br><br><div class="gmail_quote">On Fri, Sep 16, 2011 at 2:59 PM, Maria Karpman <span dir="ltr"><<a href="mailto:maria.karpman@karpmanconsulting.net">maria.karpman@karpmanconsulting.net</a>></span> wrote:<br>
<blockquote style="margin: 0px 0px 0px 0.8ex; padding-left: 1ex; border-left-color: rgb(204, 204, 204); border-left-width: 1px; border-left-style: solid;" class="gmail_quote"><div lang="EN-US" vlink="purple" link="blue"><div>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125); font-size: 11pt;">Pasha and Bill,<u></u><u></u></span></p><p class="MsoNormal"><span style="color: rgb(31, 73, 125); font-size: 11pt;"><u></u> <u></u></span></p><p class="MsoNormal">
<span style="color: rgb(31, 73, 125); font-size: 11pt;">I also often use this keyword, but usually increase the fraction incrementally by 0.1 instead of just setting it to 1, to avoid out-of-control behavior described in DOE2 help. Here is the related quote: <u></u><u></u></span></p>
<p style="margin-left: 0.5in;" class="MsoNormal">Some reverse-acting VAV systems may go out of control if the maximum heating airflow is not restricted . As the zone temperature drops, the box progressively opens to deliver more air. However, since the supply air is usually lower than the zone temperature, more coil energy is required to offset the non-useful reheat (difference between zone temperature and supply air temperature), potentially leaving less coil/boiler capacity available for useful heating. As a result, a terminal at full flow may deliver less useful heating than at lower flow, resulting in an out-of-control situation; the box may go to full flow even though a reduced flow would heat more effectively. The solution is to restrict the maximum flow during reheatng coil and/or boiler is not sized sufficiently large, <u></u><u></u></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125); font-size: 11pt;">I did see this scenario happen in some projects, when adjusting the value of the keyword up beyond certain point increased heating, cooling, and fan power, but did not help much with under-heating. <u></u><u></u></span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125); font-size: 11pt;">Thanks,</span><u></u><u></u></p><p class="MsoNormal"><span style="color: rgb(31, 73, 125); font-size: 11pt;">Maria <u></u><u></u></span></p><p class="MsoNormal">
<span style="color: rgb(31, 73, 125); font-size: 11pt;"><u></u> <u></u></span></p><div style="border-width: 1pt medium medium; border-style: solid none none; border-color: rgb(181, 196, 223) currentColor currentColor; padding: 3pt 0in 0in;">
<p class="MsoNormal"><b><span style="font-size: 10pt;">From:</span></b><span style="font-size: 10pt;"> <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>On Behalf Of </b>Pasha Korber-Gonzalez<br>
<b>Sent:</b> Friday, September 16, 2011 3:23 PM<br><b>To:</b> Bishop, Bill<br><b>Cc:</b> <a href="mailto:equest-users@lists.onebuilding.org" target="_blank">equest-users@lists.onebuilding.org</a><br><b>Subject:</b> Re: [Equest-users] Tip for unmet heating hours in VAV systems<u></u><u></u></span></p>
</div><div><div></div><div class="h5"><p class="MsoNormal"><u></u> <u></u></p><div><p class="MsoNormal">Thanks Bill--I think this will be helpful. I currently have a baseline model with whacked underheated hours and with upsizing ratios and autosized calcs nothing is changing for me. I will try this input adjustment and see if it works.<u></u><u></u></p>
</div><div><p class="MsoNormal"> <u></u><u></u></p></div><div><p class="MsoNormal">Thanks for sharing!<u></u><u></u></p></div><div><p style="margin-bottom: 12pt;" class="MsoNormal">Pasha<u></u><u></u></p></div><div><p class="MsoNormal">
On Fri, Sep 16, 2011 at 8:33 AM, Bishop, Bill <<a href="mailto:wbishop@pathfinder-ea.com" target="_blank">wbishop@pathfinder-ea.com</a>> wrote:<u></u><u></u></p><div><div><p class="MsoNormal">Thought I’d share a tip for addressing unmet heating hours in VAV systems using eQUEST 3.64.<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal">eQUEST 3.64 adds the HMAX-FLOW-RATIO keyword in System -> Fans -> Flow Parameters. The default value is the greater of the fan MIN-FLOW-RATIO and 0.5, but this value is determined by the program and you don’t see it when you look at the Flow Parameters tab. Entering a value of 1.0 corrected an unmet heating hours problem for me that appeared when I opened a model in 3.64 that I originally created in 3.63. This works for both VAVS and PVAVS system types.<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal">Regards,<u></u><u></u></p><p class="MsoNormal">Bill<u></u><u></u></p><p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal"><img border="0" alt="Senior Energy Engineer" src="cid:image001.jpg@01CC7486.7F10F840" width="486" height="116"><u></u><u></u></p>
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