<div dir="ltr">Nick,<div><br></div><div>Small world, I seem to run into this a lot too.</div><div><br></div><div>As for the eQuest side, I'll throw in a futile effort that I tried. It's been a few years since I've tried, so it may be worth another shot with 2.3, and also I may have been doing something wrong. Under the coil options, there is a CHW-Coil-Cap-fFluidFlow. The default looks something like this.</div><div><br></div><div><div><img src="cid:ii_jx6iddt13" alt="image.png" width="249" height="182" style="margin-right: 0px;"><br></div></div><div><br></div><div>DOE2 uses this curve to control the cooling valve to modulate its hourly output to meet a setpoint. In other words, if I need X Btu/hr of chilled water to get Y Deg-F air off the coil, how much water flow is that? My thought was to trick DOE2 with a custom curve which has almost zero capacity except near 100% flow. This would make the controller run nearly 100% flow through the coil regardless of load. This curve would be like the blue one below.</div><div><br></div><div><div><img src="cid:ii_jx6ijvvm4" alt="image.png" width="267" height="196" style="margin-right: 0px;"><br></div></div><div><br></div><div>You are limited to cubic, quadratic, or linear profiles with this curve, so creating this shape can be a little tricky. This should force the valve into nearly 100% flow all the time, but it won't model any space temperature effects.</div><div><br></div><div>To try to model space temperature effects of a stuck valve that isn't modulating, I've tried to create a curve with near constant capacity like the green one below. It needs to be slightly linear, or else you will put the program into a death spiral.</div><div><br></div><div><div><img src="cid:ii_jx6is8565" alt="image.png" width="276" height="197" style="margin-right: 0px;"><br></div></div><div><br></div><div>In theory, this coil should put out near constant cooling output regardless of the "flow" that DOE2 puts through it. Again, last time I went down this rabbit hole, I was unsuccessful, but it may be worth another shot.</div><div><br></div><div>This doesn't quite meet your explicit option, but one 3rd party option is to use the LBL buildings library with something like open modelica. The library has a built-in comfort model (Fanger model), and you could build a hydronic system around it. Downside is the overhead in learning modelica, and you will likely have to create a single-zone pet model to study the problem in general terms.</div><div><br></div><div>Definitely an issue with current state of building modeling tools is the slant towards new construction and fully functioning equipment. I shouldn't say issue because maybe this meets 90% of modeling needs? But those of us who live in the retrofit space run into these things all the time. What about a pneumatic thermostat that is leaking air and so is causing a cooling valve to sit constantly at 80% open? Or VFDs that are put in hand at 40 HZ, or control valves that are manually overridden?</div><div><br></div><div>Aaron</div><div><br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Jun 21, 2019 at 1:37 PM Nicholas Caton via Equest-users <<a href="mailto:equest-users@lists.onebuilding.org">equest-users@lists.onebuilding.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p class="MsoNormal">Apologies for the cross-post, however I wanted to ask this question from 2 angles and I feel both communities may benefit from the discussion (if I can spark one).<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">A common reality I’ve observed with “real-world” hydronic systems is that system coils and baseboard/radiator loops fall into a state coined
<u>wild coils</u>. Rather than modulating flow to maintain a measured supply air or room temperature setpoint, flow is
<u>uncontrolled</u>. A heating or reheat coil for example will end up dumping heat at all times the associated circulation loop is active, independent of its associated system’s fan operation, cooling coil activity, or thermostat signals requesting more/less
heating. Occupants in response to wild coils, when they cay, will end up using windows, propping open doorways, plugging in local space heaters / circ fans, and generally suffering in terms of comfort. In just about every case, this scenario presents a win-win
in terms of improved occupant comfort potential in parallel with energy savings potential for whoever is paying the bills.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Causes for this situation I’ve encountered more than once include:<u></u><u></u></p>
<ul style="margin-top:0in" type="disc">
<li class="gmail-m_-2354524181500603354MsoListParagraph" style="margin-left:0in">Manual Control valves left in an open state, with dusty cobwebs suggesting their presence is unknown to the occupants/building operators<u></u><u></u></li><li class="gmail-m_-2354524181500603354MsoListParagraph" style="margin-left:0in">Automated valves (electric or pneumatic) which have become mechanically stuck in an open, or partially open position<u></u><u></u></li><li class="gmail-m_-2354524181500603354MsoListParagraph" style="margin-left:0in">Automated valves (electric or pneumatic) which are otherwise busted due to upstream pneumatic line/system issues or mechanical failures of the moving parts at the valve<u></u><u></u></li><li class="gmail-m_-2354524181500603354MsoListParagraph" style="margin-left:0in">A valve was never designed and/or installed and/or wired up for control in the first place<u></u><u></u></li></ul>
<p class="gmail-m_-2354524181500603354MsoListParagraph"><u></u> <u></u></p>
<p class="MsoNormal">For all of this however, I have always struggled in approximating the energy and comfort impacts of “wild” coils in my building energy simulations. Quantifying this impact with some degree of confidence is difficult, but desirable in cases
where I am calibrating to existing utility bills (read: always) and/or asserting the utility savings and comfort improvement impact for fixing/addressing such situations.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><b>For the [bldg-sim] family:</b> Are there any 3<sup>rd</sup> party tools, models, or other energy simulation platforms with explicit options for evaluating the comfort and energy impacts of wild coil situations? Is there any research
I could be pointed towards exploring this topic?<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><b>For the [eQuest-users] crowd:</b> Can anyone share a best practice or recommendation for simulating this sort of problem-state within a doe2/eQuest model? As far as I know, the native input options are essentially limited to a pair
of “working” coil modulation states: TWO-WAY and THREE-WAY. Here’s an example doe2 reference entry, with language that repeats a couple times over for different scenarios:<u></u><u></u></p>
<p class="MsoNormal" style="margin-left:0.5in"><img width="639" height="253" style="width: 6.6562in; height: 2.6354in;" id="gmail-m_-2354524181500603354Picture_x0020_3" src="cid:16b7b8dc778692e333"><u></u><u></u></p>
<p class="MsoNormal">I personally have taken different approaches, with none being particularly satisfactory. These have included introducing process loads onto the loops concurrently with “free” internal energy source definitions to get those losses dumped
into the spaces experiencing discomfort. I have also played with artificially bumping the thermostat schedules around to reflect measured, uncomfortable temperature states…<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Any solutions/experiences/shared-commiseration would be very welcome!
<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">~Nick<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><span style="font-family:Arial,sans-serif;color:rgb(58,122,70)"><img width="726" height="9" style="width: 7.5625in; height: 0.0937in;" id="gmail-m_-2354524181500603354Picture_x0020_1" src="cid:16b7b8dc7784cff311" alt="cid:image005.png@01D515A3.47EDD880"><u></u><u></u></span></p>
<p class="MsoNormal"><b><span style="font-family:Arial,sans-serif;color:rgb(58,122,70)">Nick Caton, P.E., BEMP</span></b><span style="color:rgb(58,122,70)"><u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(98,100,105)"> Senior Energy Engineer</span><span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(31,73,125)"><br>
</span><span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(98,100,105)"> Regional Energy Engineering Manager<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(98,100,105)"> Energy and Sustainability Services</span><span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(31,73,125)"><br>
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<p class="MsoNormal"><span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(98,100,105)">913 . 564 . 6361<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(98,100,105)">785 . 410 . 3317<u></u><u></u></span></p>
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<p class="MsoNormal"><u><span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(98,100,105)"><a href="mailto:nicholas.caton@se.com" target="_blank"><span style="font-family:Calibri,sans-serif;color:rgb(98,100,105)">nicholas.caton@se.com</span></a></span></u><span style="font-size:9pt;color:rgb(31,73,125)"><u></u><u></u></span></p>
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