<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Zone exhaust is presumed to exhaust directly to the outside without going back to the system, i.e. it is assumed that you are specifying a separate zonal exhaust fan that is not connected to the main VAV system. If you remove the zone exhaust, the system level exhaust will be determined by the outdoor air fraction of the supply air. This outdoor air fraction will depend on the demand for outdoor air from the zones. i.e. the outdoor air is specified at the zone level, and determines the outdoor air supply at the system level. <div class=""><br class=""></div><div class="">Hope that helps,</div><div class="">Dan</div><div class=""><br class=""><div class="">—<br class="">Daniel Knapp PhD, P Phys, LEED AP O+M<br class=""><a href="mailto:danielk@arborus.ca" class="">danielk@arborus.ca</a><br class=""><br class="">Energy Efficiency Expert<br class="">Arborus Consulting<br class="">76 Chamberlain Ave<br class="">Ottawa ON K1S 1V9<br class="">(613) 234-7178</div></div><div class="">
—<br class="">Daniel Knapp PhD, P Phys, LEED AP O+M<br class=""><a href="mailto:danielk@arborus.ca" class="">danielk@arborus.ca</a><br class=""><br class="">Energy Efficiency Expert<br class="">Arborus Consulting<br class="">76 Chamberlain Ave<br class="">Ottawa ON K1S 1V9<br class="">(613) 234-7178
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<br class=""><div><blockquote type="cite" class=""><div class="">On Feb 1, 2016, at 11:28 AM, Miles H. Martschink <<a href="mailto:miles.martschink@rmf.com" class="">miles.martschink@rmf.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="WordSection1" style="page: WordSection1; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Hello All,<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">I am trying to model an enthalpy energy recovery wheel on a VAV air handler serving multiple zones, and I cannot seem to get any exhaust air to pass through the wheel. I have specified the design exhaust loads at the Zonal Level and I have also setup the wheel control sequence using values that others on this forum have posted:<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in;" class=""><span style="font-family: Symbol;" class=""><span class="">·<span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman';" class=""> <span class="Apple-converted-space"> </span></span></span></span>Operation = OA Exhaust DT<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt 1in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in;" class=""><span style="font-family: 'Courier New';" class=""><span class="">o<span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman';" class=""> <span class="Apple-converted-space"> </span></span></span></span>DT = 5 degree F<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in;" class=""><span style="font-family: Symbol;" class=""><span class="">·<span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman';" class=""> <span class="Apple-converted-space"> </span></span></span></span>Operating Mode = OA Heat/Cool<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in;" class=""><span style="font-family: Symbol;" class=""><span class="">·<span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman';" class=""> <span class="Apple-converted-space"> </span></span></span></span>Make up Air Temp Cntrl = Mixed Air Reset<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in;" class=""><span style="font-family: Symbol;" class=""><span class="">·<span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman';" class=""> <span class="Apple-converted-space"> </span></span></span></span>Capacity Control = Bypass OA<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Whenever I run the model I get an error stating, “Energy Recovery ventilator: S1 Sys (VAVS) has an exhaust flow 50% of the supply flow. Performance may be compromised. OA & Exhaust: 7313. 0.” The total sum of all the Zonal Exhaust Loads in 5505 CFM, and none of this is making it to the wheel. Does anyone have any insight as to what I might be doing wrong here? My end goal is to have the wheel modulate the return airflow in order to match the Outside Air CFM demand by the VAV system. Any input is greatly appreciated.<span class="Apple-converted-space"> </span><o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Thanks,<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class=""><span style="font-size: 12pt; color: rgb(20, 76, 92);" class="">Miles Martschink, Jr<o:p class=""></o:p></span></b></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 12pt; color: rgb(20, 76, 92);" class="">Mechanical Design Engineer<o:p class=""></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 9pt; color: rgb(20, 76, 92);" class="">______________________________<br class=""></span><span style="font-size: 5pt; color: rgb(20, 76, 92);" class=""><br class=""></span><b class=""><span style="font-size: 12pt; color: rgb(20, 76, 92);" class="">RMF Engineering<br class=""></span></b><span style="font-size: 10.5pt; color: rgb(71, 77, 79);" class="">Reliability. 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