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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Interesting question about DOAS and the current fan power allowance for system types 1 & 2. I think we very much need an update to Appendix G to account for
the fan power requirements of the dedicated outdoor air systems that are (in my opinion) required for unitary type systems such as PTACs as well as the PSZ-ACs.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I’m in the south, and so we cannot count on simply opening the windows to meet our ASHRAE ventilation requirements, at least not anymore
</span><span style="font-size:11.0pt;font-family:Wingdings;color:#1F497D">J</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> (we did exactly that through until ~ 1988 at the school in Louisiana I attending while growing
up, at which point we finally got air conditioning and promptly shut the windows).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I would argue that a DOAS is necessary in the south to properly provide outside air, while maintaining acceptable building humidity conditions, for unitary
type systems. Anything less is negligent design, in our opinion. However, at the present time, Appendix G assumes that PTACs (or PSZ-ACs) will bring outside air continuously into the zones and cycle the compressor to control room temp while ignoring humidity.
You can’t do that in real life. Where we have seen that done, you get condensation and eventually mold, and eventually you get sued.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I think you have run into a gray area for which there is no good answer currently. Assuming that you are working on a LEED project, you’ll have to hope that
you run up against a LEED reviewer that will exercise good judgment and common sense, and understand that this area is not covered by Appendix G currently and that a reasonable allowance for DOAS fan power should work and should be allowed, since it can be
argued that DOAS are required to meet the ASHRAE 62 ventilation requirements.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The issue is that the 0.3 watts/CFM is only enough fan power allowance to account for a motel “thru the wall” type unit. No external ductwork (supply or return),
barely a filter, and certainly no allowance for a DOAS.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">My recommended solution would be to model the DOAS with the same fan power in the Baseline as in the Proposed.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">That’s conservative in my opinion. You aren’t taking credit for any fan energy savings associated with the DOAS, but neither are you unnecessarily penalizing
yourself either for something that is required for the Proposed Design.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Regarding AHRI fan power assumptions, I’m not sure about that question. But I did a quick test in eQuest. I built a quick sample model in the DD wizard, selected
PTAC, and entered 11 EER for cooling efficiency. I then went to the detailed mode and the EIR conversion was the exact same that eQuest does for any system
</span><span style="font-size:11.0pt;font-family:Wingdings;color:#1F497D">à</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> EIR = 0.2580 for EER =11.0. Consequently, we know that eQuest is using the 365 watts/KCFM conversion.
But that’s eQuest. I don’t know what AHRI 310 uses for fan power assumption, if anything. I looked into this a while back and I don’t think that eQuest is on the same page with the AHRI fan power assumptions used in the ratings. I could be incorrect, however.
Another thing is that the fan power assumptions used in the AHRI ratings have absolutely nothing to do with the Appendix G fan power requirements. I do know that. I think we need to let eQuest do its thing in the wizard/detailed interface transition, and
then go to the detailed interface and change the EIR ourselves to whatever is appropriate, if we can figure out what AHRI is doing regarding fan power assumptions.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hope this helps!
</span><span style="font-size:11.0pt;font-family:Wingdings;color:#1F497D">J</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:8.0pt;font-family:"Calibri","sans-serif";color:#339966"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#339966">JAH<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:8.0pt;font-family:"Calibri","sans-serif";color:#339966"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><i><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#339966">James A. Hess, PE, CEM, BEMP</span></i></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><br>
Energy Engineer<br>
TME, Inc.<br>
Little Rock, AR<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Mobile: (501) 351-4667<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> equest-users-bounces@lists.onebuilding.org [mailto:equest-users-bounces@lists.onebuilding.org]
<b>On Behalf Of </b>Kathryn Kerns<br>
<b>Sent:</b> Monday, February 25, 2013 5:57 PM<br>
<b>To:</b> equest-users@lists.onebuilding.org<br>
<b>Subject:</b> [Equest-users] Baseline PTAC Fan Energy for a Proposed Merv13 + Return Duct System<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">Everyone, I have been modeling some dormitories with a proposed HVAC system involving a DOA with a full exhaust air HX and MERV 13 filters. The puzzle is what to do about the
baseline PTAC fan power energy? If I use 0.3 w/cfm as Appendix G suggests, my PTAC baseline system does not account for a fully ducted return\exhaust or MERV 13 filters. The commercial fan power equation for systems 3-8 accounts for this, but I am not supposed
to use that formula for System 1 and 2.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">Another puzzle is if I develop an cooling EIR value for my baseline PTAC using the 365 w/kCFM conversion rule and equate that with 0.3 w/cfm, what happened to the other 65
w/kCFM? <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">Maybe ARI 310/380 doesn’t use 365 w/cfm fan power? I read it and didn’t find any statement regarding fan power requirements, but I assume it works the same as ARI 210/240?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">I am wondering if a compromise of
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif""> PTAC fan power = CFM<i>s</i> *0.000365 + A where A= PD*CFM<i>s</i> /4131 and PD = 1.4<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">might be a reasonable solution?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif""> PTAC fan power = 0.00063 kw/cfm<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">Does anyone else have experience with this puzzle?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="section1" style="margin:0in;margin-bottom:.0001pt"><strong><span style="font-family:"Arial","sans-serif";color:black">Kathryn Kerns</span></strong><o:p></o:p></p>
<p class="section1" style="margin:0in;margin-bottom:.0001pt"><em><b><span style="font-size:11.0pt;font-family:"Arial","sans-serif";font-style:normal">Systems Specialist</span></b></em><o:p></o:p></p>
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</span><span style="font-variant:small-caps;color:teal">Engineers, Inc.<o:p></o:p></span></strong></p>
<p class="section1" style="margin:0in;margin-bottom:.0001pt"><strong><span style="font-size:9.0pt;color:black">| Ph: 253.922.0446 | Fx: 253.922.0896 |</span></strong><span style="font-size:7.0pt;color:black">
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