<div dir="ltr">Thanks for the input Nathan. Since I do have an ERV, I am trying to deal with that more complicated issue. I actually ended up using a Powered Induction Unit as suggested by Elizabeth and that seems to be working well.<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Apr 21, 2016 at 10:04 AM, Nathan Miller <span dir="ltr"><<a href="mailto:nathanm@rushingco.com" target="_blank">nathanm@rushingco.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">I’m just getting back from a vacation, so sorry for the delayed response on this, but there is a way to force a PSZ system to have discharge air temp control.
I’m ignoring the ERV portion of your system right now because that complicates matters.
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">We use this methodology frequently to model corridor/DOAS systems for multifamily projects. Note that this is only accounting for the energy use of the ventilation
air. I’m assuming you will model separate systems for the dwelling units to meet the space conditioning demands (basically it looks like you are supplying neutral vent air, which won’t have much impact on how much load shows up on the in-unit VRF).
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<p><u></u><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><span>1)<span style="font:7.0pt "Times New Roman"">
</span></span></span><u></u><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Create a new space (call it “DOAS Dummy space” or something). Make the size minimal- 1’x1’x1’ works well. Make sure there are no internal loads or walls/roofs/floors
assigned to it. <u></u><u></u></span></p>
<p><u></u><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><span>2)<span style="font:7.0pt "Times New Roman"">
</span></span></span><u></u><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Create a new zone (call it “DOAS Dummy zone” or something). Assign the dummy space to the zone. Give the zone Heating/Cooling t-stat schedules that
are equivalent to the discharge air temp range you want to control to. In your example you’d have a 24/7 heating schedule at 73 deg F and 24/7 cooling schedule at 75 deg.
<u></u><u></u></span></p>
<p><u></u><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><span>3)<span style="font:7.0pt "Times New Roman"">
</span></span></span><u></u><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Give this dummy zone control of your PSZ unit. Because there are no loads in the space, the PSZ unit should discharge air between 73-75 Deg to keep
that 1 cubic foot space at the desired temp range. You can confirm this by looking at hourly reports.
<u></u><u></u></span></p>
<p><u></u><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><span>4)<span style="font:7.0pt "Times New Roman"">
</span></span></span><u></u><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">If you have multiple conditioned zones assigned to the unit, they will “come along for the ride” meaning they will get the same supply air temp, with
no consideration for their space temps. You may have to assign a realistic “relaxed” t-stat schedule to those space to avoid lots of unmet load hours.<u></u><u></u></span></p>
<p><u></u><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><span>5)<span style="font:7.0pt "Times New Roman"">
</span></span></span><u></u><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Depending on how the vent air is being distributed in the dwelling units, you might have to play around with how the fan power is assigned. For example-
do the in unit fans have to run 24/7 to distribute the vent air, or do they only cycle to meet the loads in the space?
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Having an ERV can significantly complicate this modeling method depending on where the return air is coming from (and the expected temperature of that return
air) for the heat-recovery. <u></u><u></u></span></p>
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<b><span style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#6f1200">Nathan Miller, PE, LEED AP BD+C</span></b><b><span style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#632423"> –
</span></b><i><span style="font-size:8.0pt;font-family:"Verdana",sans-serif;color:black">Mechanical Engineer/Senior Energy Analyst</span></i><b><span style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#632423"><u></u><u></u></span></b></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Equest-users [mailto:<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">equest-users-bounces@lists.onebuilding.org</a>]
<b>On Behalf Of </b>Michael Campbell via Equest-users<br>
<b>Sent:</b> Monday, April 18, 2016 4:07 PM<br>
<b>To:</b> Elizabeth Gillmor <<a href="mailto:elizabeth@energetics-eng.com" target="_blank">elizabeth@energetics-eng.com</a>><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] Using PSZ as DOAS?<u></u><u></u></span></p><div><div class="h5">
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<p class="MsoNormal">Thank you Elizabeth!<u></u><u></u></p>
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<p class="MsoNormal">On Mon, Apr 18, 2016 at 3:30 PM, Elizabeth Gillmor <<a href="mailto:elizabeth@energetics-eng.com" target="_blank">elizabeth@energetics-eng.com</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal">Hi Michael,<u></u><u></u></p>
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<p class="MsoNormal">I have always used a Powered Induction Unit system type for DOAS systems. (Or standard Induction Unit system if CHW instead of DX.) This should give you the control and heat source capability that you need.<u></u><u></u></p>
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<p class="MsoNormal">Good luck!<u></u><u></u></p>
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<p class="MsoNormal">Elizabeth<u></u><u></u></p>
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<p class="MsoNormal"><b>Elizabeth Gillmor </b><b><span style="font-size:7.5pt">PE, BEMP, LC, LEED AP</span></b><u></u><u></u></p>
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<p class="MsoNormal"><b><span style="font-size:18.0pt;font-family:"Arial",sans-serif;color:#38761d;background:white">e n e r g e t i c s </span></b><b><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#38761d">consulting engineers, llc</span></b><u></u><u></u></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;color:#666666;background:white"><a href="http://energetics-eng.com" target="_blank">energetics-eng.com</a> |</span><span style="color:#666666"> <a href="tel:303.619.0091" target="_blank">303.619.0091</a></span><u></u><u></u></p>
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<p class="MsoNormal">On Mon, Apr 18, 2016 at 12:52 PM, Michael Campbell via Equest-users <<a href="mailto:equest-users@lists.onebuilding.org" target="_blank">equest-users@lists.onebuilding.org</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal">I also have a follow up question. Is there any system type that I can use which will allow me to select heat pump as the heating source and also be controlled by the supply air temperature? It appears that constant temp control would
be available for PMZS but I cannot use heat pump heat with this type of system.<u></u><u></u></p>
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<p class="MsoNormal">On Mon, Apr 18, 2016 at 9:37 AM, Michael Campbell <<a href="mailto:mcamp1206@gmail.com" target="_blank">mcamp1206@gmail.com</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Hello,<u></u><u></u></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">I'm trying to use a PSZ system as a DOAS. The system I'm trying to model uses and ERV tied to a heat pump to supply fresh air to common areas and dwelling units. There are then separate VRF systems for space
conditioning. The DOAS is designed to supply a constant temperature outside air (73F when heating, 75F when cooling). How can I make the PSZ system in equest supply a constant temperature supply air?<u></u><u></u></p>
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<p class="MsoNormal">Thank you<u></u><u></u></p>
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