If you have heavy heating loads in the space, then should try to replicate that by putting in a heat load in the internal energy tab of the spaces. This will force the higher return temperatures and make it unnecessary to have re-heat coils. <div>
<br></div><div>This may work for you, because it seems like in reality, the spaces don't require the reheat coils and the spaces are kept to temperature.</div><div><br></div><div>Hope this is helpful,</div><div><br></div>
<div>Rob<br><br><div class="gmail_quote">On Fri, May 4, 2012 at 11:00 AM, R B <span dir="ltr"><<a href="mailto:slv3sat@gmail.com" target="_blank">slv3sat@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>I am assuming this is an existing building. I have always had this issue. I do all the stuff that you have and use the reheat also, if the unmet hours are too many. I also look at the SS-F report to see how low the temps are and when (hourly report) - if they are acceptable, then I leave the reheat out. You could also widen the throttling range - there might be unmet hours in the actual building - people just don't complain if it is a few degrees less/more than the thermostat. You should look at the hourly report to see if the heating coil is coming on (these reports are not very clean - since it is not clear for what point in the air stream eQuest is reporting the temps). Do you have VAV boxes - sometimes I have seen that a constant volume system has a VFD added to the fan, without VAV boxes in the space. You could reduce the min flows to zero and see if that helps. I haven't dug deeper into it, but I think the VAV system is going to set the supply temps low when even one zone needs cooling/less heating and so others will need reheat. If things are working smoothly in the existing building, then the zones must be similar and may not need too much variation in supply temps for different zones. I haven't used MZ - but that would probably work - what is the difference in energy consumption between the two options? I have not been comfortable with the economizer and MZ together.</div>
<div> </div><div>I will be curious to know what you find.</div><div>-Rohini<br><br></div><div class="gmail_quote"><div><div class="h5">On Fri, May 4, 2012 at 8:48 AM, Dana Etherington <span dir="ltr"><<a href="mailto:Dana.Etherington@crbusa.com" target="_blank">Dana.Etherington@crbusa.com</a>></span> wrote:<br>
</div></div><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><div class="h5"><div lang="EN-US" vlink="purple" link="blue">
<div><p class="MsoNormal">
Hi folks,<u></u><u></u></p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">We are modeling a large facility operating with multiple VAV AHUs with central heating and cooling coils, but no re-heat at the zones. There are high heat loads in the spaces and therefore higher return air temperatures than the norm. <u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">When I remove the re-heat from the systems I have excessive unmet load hours (heating). I have specified “HEAT-SET-T” to activate the central heating coil. I also have cooling control set to “warmest” and heat control set to “coldest”. If I do not set the coil capacity it is still not meeting the loads. The only way I have been able to eliminate these unmet hours is by adding the re-heat back in or changing it to a multi-zone (MZS) system with all the same parameters. <u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">If I model this scenario using the multi-zone system in eQuest to get around this would that be vastly different than VAV with no re-heat? Has anyone had this issue before? Any insight is appreciated. Thanks!<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">-Dana<u></u><u></u></p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal"><b><span style="color:rgb(89,89,89);font-family:"Arial","sans-serif";font-size:9pt">Mr. Dana Etherington, E.I.T., LEED AP BD+C </span></b><span style="color:rgb(89,89,89);font-family:"Arial","sans-serif";font-size:9pt">| <b>CRB </b>| One Kendall Square Ste B2202 | Cambridge, MA 02139</span><span style="color:rgb(31,73,125)"><u></u><u></u></span></p>
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