I'd leave it this way; You would be recovering heat from your exhaust and maybe a bit from your return air, It's all good. Just be sure to add the extra sp in at the return level to account for the ERV.<br><br>Carol<br>
<br><div class="gmail_quote">On Wed, Mar 17, 2010 at 7:43 AM, Nick Caton <span dir="ltr"><<a href="mailto:ncaton@smithboucher.com">ncaton@smithboucher.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">Brian/Carol, thanks very much
for your replies!</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">I’d like to spell out a simple
example to both illustrate the concept and verify my understanding:</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><u><span style="color: rgb(31, 73, 125);">Starting System Flows (CFM):</span></u></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">1,000 Supply Air</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">300 Outside Air</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">200 Exhaust Air, specified at a the
zone(s) level.</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">800 Return Air</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">To correctly model energy
recovery with this system, we need to remove the 200 CFM zonal-specified
exhaust, and add it to the return air stream.</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><u><span style="color: rgb(31, 73, 125);">Energy-recovering System,
corrected:</span></u></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">1,000 Supply Air</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">300 Outside Air</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">1000 Return Air</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">Am I understanding this
correctly?</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">Thanks again!</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"><br>
~Nick</span></p><div class="im">
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"> </span></p>
<div>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"><img src="cid:image001.jpg@01CAC5B5.94ADA1C0" alt="cid:489575314@22072009-0ABB" width="119" height="37"></span><b><span style="color: rgb(45, 77, 94);"></span></b></p>
<p class="MsoNormal"><b><span style="color: rgb(45, 77, 94);"> </span></b></p>
<p class="MsoNormal"><b><span style="color: rgb(45, 77, 94);">NICK CATON, E.I.T.</span></b><b><span style="font-size: 12pt; color: rgb(45, 77, 94);"></span></b></p>
<p class="MsoNormal"><span style="font-size: 7.5pt; color: rgb(204, 153, 0);">PROJECT ENGINEER</span><span style="font-size: 7.5pt; font-family: "Times New Roman","serif"; color: rgb(204, 153, 0);"></span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">25501 west
valley parkway</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">olathe ks 66061</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">direct 913
344.0036</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">fax 913
345.0617</span></p>
<p class="MsoNormal"><i><span style="font-size: 10pt; color: rgb(45, 77, 94);">Check out
our new web-site @ </span></i><span style="color: rgb(31, 73, 125);"><a href="http://www.smithboucher.com" title="blocked::www.smithboucher.com" target="_blank"><span style="font-size: 10pt;">www.smithboucher.com</span></a></span><u><span style="font-size: 10pt; color: blue;"> </span></u><span style="color: rgb(31, 73, 125);"></span></p>
</div>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"> </span></p>
</div><div>
<div style="border-style: solid none none; border-color: rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color; border-width: 1pt medium medium; padding: 3pt 0in 0in;">
<p class="MsoNormal"><b><span style="font-size: 10pt; color: windowtext;">From:</span></b><span style="font-size: 10pt; color: windowtext;"> Brian Fountain
[mailto:<a href="mailto:bfountain@greensim.com" target="_blank">bfountain@greensim.com</a>] <br>
<b>Sent:</b> Tuesday, March 16, 2010 10:10 PM<br>
<b>To:</b> Nick Caton<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] System-Level Exhaust??? How?</span></p>
</div>
</div><div><div></div><div class="h5">
<p class="MsoNormal"> </p>
<p class="MsoNormal">Nick,<br>
<br>
DOE-2 enforces a mass balance at the system level. Whatever OA that is
not exhausted at the zone level must be returned to the central system and
exhausted through your heat recovery device. By defining the OA volume flow
rate, you are also defining the exhaust volume flow rate.<br>
<br>
Nick Caton wrote: </p>
<p class="MsoNormal">I need have an ERV which moves all the exhaust and supplies
conditioned OA to 2 of 3 FPVAV air handlers. I’ve specified the
appropriate enthalpy wheel specifics at the two affected PIU systems, maintaining
identical efficiency properties and breaking down CFM’s and fan/auxiliary
power figures by weighting each by the supplied OA amount.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">I understand from the help files that zonally-specified
exhaust air does not play into heat-recovery, when we specify energy recovery
at the system level (help section is copied below and highlighted for
reference).</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">I take it then I’m supposed to zero out all zonally
entered exhaust air flows, sum up the flows and add at the system level…
but then <u>how/where do I specify system-level exhaust CFM rates</u>? </p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">I’ve tried to enter
EXHAUST-FLOW = #### under the
systems in question in the .inp file, but it introduces the following error: </p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">*13131*
EXHAUST-FLOW = 2550</p>
<p class="MsoNormal">*ERROR********* ============
*****************************************************************UNKNOWN
KEYWORD or PREVIOUS .. MISSING </p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">More errors ensue, and a long string of things appear to be
defaulted/lost when I continue to open the file… something is obviously
wrong with this approach.</p>
<p class="MsoNormal"><b><span style="color: rgb(45, 77, 94);"> </span></b></p>
<p class="MsoNormal"><img src="cid:image001.jpg@01CAC5B5.94ADA1C0" alt="cid:489575314@22072009-0ABB" width="119" border="0" height="37"></p>
<p class="MsoNormal"><b><span style="color: rgb(45, 77, 94);"> </span></b></p>
<p class="MsoNormal"><b><span style="color: rgb(45, 77, 94);">NICK CATON, E.I.T.</span></b></p>
<p class="MsoNormal"><span style="font-size: 7.5pt; color: rgb(204, 153, 0);">PROJECT ENGINEER</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">25501 west
valley parkway</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">olathe ks 66061</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">direct 913
344.0036</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">fax 913 345.0617</span></p>
<p class="MsoNormal"><i><span style="font-size: 10pt; color: rgb(45, 77, 94);">Check out
our new web-site @ </span></i><span style="color: rgb(31, 73, 125);"><a href="http://www.smithboucher.com" title="blocked::www.smithboucher.com" target="_blank"><span style="font-size: 10pt;">www.smithboucher.com</span></a></span><u><span style="font-size: 10pt; color: blue;"> </span></u></p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><b><span style="font-size: 10pt; font-family: "Times New Roman","serif";">EXHAUST-FLOW</span></b></p>
<p class="MsoNormal"><span style="font-size: 12pt; font-family: "Times New Roman","serif";">Flow
rate of the zone's exhaust fan. This entry can be omitted if there is no
exhaust from the zone, if there is only central exhaust by way of the system
return, or if the exhaust tracks the supply flow (see AIRFLOW-TRACKING). If
specified, EXHAUST-STATIC should also be entered. The exhaust fan may be either
constant flow or variable flow. </span></p>
<p class="MsoNormal"><span style="font-size: 12pt; font-family: "Times New Roman","serif";">If
exhaust air make-up is via the air handler (EXHAUST-SOURCE = AIR-HANDLER), then
the exhaust fan can operate only only when the system supply and return fans
operate (see SYSTEM:FAN-SCHEDULE or SYSTEM:EXHAUST-FAN-SCH).</span></p>
<p class="MsoNormal"><span style="font-size: 12pt; font-family: "Times New Roman","serif"; color: red;">The SYSTEMS program simulates heat recovery from central exhaust
only, not from zone exhaust. If heat is to be recovered, zone exhaust should
not be entered but rather allowed to default to the central system. Return fan
static should be adjusted, on a weighted average basis, to reflect zone exhaust
fan conditions. </span></p>
<p class="MsoNormal"><span style="font-size: 12pt; font-family: "Times New Roman","serif";">The
program will not allow SYSTEM:MIN-OUTSIDE-AIR to be less than the sum of
EXHAUST-FLOWs for all zones divided by the sum of supply flows for all zones.
That is, MIN-OUTSIDE-AIR will not restrict the operation of exhaust fans. The
exception is when EXHAUST-SOURCE = INFILTRATION, in which case zonal exhaust
does not affect air handler outside air requirements.</span></p>
<p class="MsoNormal"> </p>
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