Jason,<br><br>I searched the archives to find this explanation of throttling range written by Steve Gates. He explains how it works and how eQUEST counts hours outside of the throttling range. This should help.<br><br>Carol<br>
<br><pre>Throttling range is the temperature band between no output and full output, <br>with the setpoint in the middle of the range. If the VAV cooling setpoint <br>is 76F with a throttling range of 2F, then the VAV box is at minimum position<br>
at75F, and at maximum at 77F.<br><br>The BEPS and BEPU reports count hours as outside the throttling range if the<br>zone temperature is more than 1F outside the temperature band. In the above<br>example, a zone greater than 78F or less than 74F would be considered out of<br>
control.<br><br><font style="font-family: courier new,monospace;" size="2"><br></font><br style="font-family: courier new,monospace;"></pre><br style="font-family: courier new,monospace;"><br style="font-family: courier new,monospace;">
<div class="gmail_quote">On Thu, Mar 10, 2011 at 9:45 AM, Jason Kirchhoff <span dir="ltr"><<a href="mailto:Jason@ibece.net">Jason@ibece.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
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<p class="MsoNormal"><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">Dear all,</span></font></p>
<p class="MsoNormal"><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p class="MsoNormal"><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">I’d like to ask for a clarification
of the throttling range in eQuest. I had been working under the assumption that
your zone setpoint is at the middle of your throttling range, meaning the conditioned
space temp drifts by +/- 0.5*TR (modifying the example from Greg’s email…with
a 75F set point and a throttling range of 8F, the system will begin cooling
when the space hits 79 and turn off when it hits 71). This seems to be somewhat
supported by the DOE-2 description which reads:</span></font></p>
<p class="MsoNormal"><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">“</span></font>The zone temperature
heating or cooling set point is assumed to be at the midpoint of the throttling
range.”</p>
<p class="MsoNormal"><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">In this case, you get an unmet hour when
the space gets above 79F.</span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;"> </span></font></p>
<p class="MsoNormal"><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">However, that same DOE-2 description
continues with this statement: </span></font></p>
<p class="MsoNormal"><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">“</span></font>If the zone
temperature is more than one THROTTLING-RANGE above the cooling set point, the
zone for that hour is considered to be undercooled.” </p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;"> </span></font></p>
<p class="MsoNormal"><font size="2" color="navy" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">That would suggest that Greg’s example
was correct – for a 75F setpoint, you get an unmet hour when the space
hits 75+8=83F. I did a google and archive search and found statements supporting
both interpretations. Can anyone clarify this with any sort of authority?</span></font></p>
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<p class="MsoNormal"><b><font size="2" color="black" face="Calibri"><span style="font-size: 11pt; color: black; font-weight: bold;">Jason Kirchhoff </span></font></b><font size="2" color="gray" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: gray;"><br>
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Oaks, CA 91423 <br>
d: (818) 305-3228 o: (818) 377-8220 f: (818) 377-8230<br>
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</span></font></b><b><i><font size="2" color="gray"><span style="font-size: 10pt; color: gray; font-weight: bold; font-style: italic;">Ideas for the built environment</span></font></i></b><font color="navy"><span style="color: navy;"></span></font></p>
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<p class="MsoNormal"><b><font size="2" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma; font-weight: bold;">From:</span></font></b><font size="2" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma;"> Greg Collins
[mailto:<a href="mailto:GCollins@glumac.com" target="_blank">GCollins@glumac.com</a>] <br>
<b><span style="font-weight: bold;">Sent:</span></b> Tuesday, March 08, 2011
11:58 AM<br>
<b><span style="font-weight: bold;">To:</span></b> Travis Miller;
<a href="mailto:equest-users@lists.onebuilding.org" target="_blank">equest-users@lists.onebuilding.org</a><br>
<b><span style="font-weight: bold;">Subject:</span></b> Re: [Equest-users] High
throttling setting and KW/CFM calc</span></font><font size="3" face="Times New Roman"><span style="font-size: 12pt; font-family: "Times New Roman";"></span></font></p>
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<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;"> </span></font></p>
<p class="MsoNormal"><font size="2" color="#1f497d" face="Calibri"><span style="font-size: 11pt; color: rgb(31, 73, 125);">Travis,</span></font></p>
<p class="MsoNormal"><font size="2" color="#1f497d" face="Calibri"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></font></p>
<p class="MsoNormal"><font size="2" color="#1f497d" face="Calibri"><span style="font-size: 11pt; color: rgb(31, 73, 125);">Bumping your throttling range up will
definitely reduce your unmet cooling/heating hours, but it's not usually the
correct approach to do so. You're basically saying that the system is
trying to maintain 75°F in cooling (hypothetically), but the cooling demand is
met as long as it's less than 75 + 8°F = 83°F. Is 83°F a comfortable
temperature for your occupants? Probably not.</span></font></p>
<p class="MsoNormal"><font size="2" color="#1f497d" face="Calibri"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></font></p>
<p class="MsoNormal"><font size="2" color="#1f497d" face="Calibri"><span style="font-size: 11pt; color: rgb(31, 73, 125);">I'd check to make sure you have adequate
zoning by looking at the SS-R report and seeing if the unmet hours are similar
between the spaces in your zone. What can happen is your system will
maintain temperature in the control zone (where the thermostat is) and the
other spaces can suffer. If all of the spaces have unmet hours, your
system capacity might off. There are lots of things that could be wrong,
but the reports are your best friend while troubleshooting..</span></font></p>
<p class="MsoNormal"><font size="2" color="#1f497d" face="Calibri"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></font></p>
<p class="MsoNormal"><font size="2" color="#1f497d" face="Calibri"><span style="font-size: 11pt; color: rgb(31, 73, 125);">Regarding your kw/cfm calc - I didn't
look at it, but the number looks reasonable if you're modeling a 90.1 baseline
system. If you're modeling an actual design, you want to use the kW (from
bhp) your fan is operating at during the design condition.</span></font></p>
<p class="MsoNormal"><font size="2" color="#1f497d" face="Calibri"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></font></p>
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<p class="MsoNormal"><b><font size="2" color="#1f497d" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: rgb(31, 73, 125); font-weight: bold;">Greg
Collins</span></font></b><font size="3" color="#1f497d" face="Times New Roman"><span style="font-size: 12pt; font-family: "Times New Roman"; color: rgb(31, 73, 125);"><br>
</span></font><font size="2" color="#1f497d" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: rgb(31, 73, 125);">GLUMAC | (949) 833-8190</span></font></p>
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<p class="MsoNormal"><b><font size="2" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma; font-weight: bold;">From:</span></font></b><font size="2" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma;"> Travis Miller
[mailto:<a href="mailto:tmiller@dcengineering.net" target="_blank">tmiller@dcengineering.net</a>] <br>
<b><span style="font-weight: bold;">Sent:</span></b> Tuesday, March 08, 2011
11:14 AM<br>
<b><span style="font-weight: bold;">To:</span></b>
<a href="mailto:equest-users@lists.onebuilding.org" target="_blank">equest-users@lists.onebuilding.org</a><br>
<b><span style="font-weight: bold;">Subject:</span></b> [Equest-users] High
throttling setting and KW/CFM calc</span></font></p>
</div>
</div>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;">I
am looking for a little help in trouble shooting a couple of setpoints on the
attached model. </span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;">The
first concern I have is my throttling setpoint. I have it 8 degrees right now.
The reason for that was to eliminate unmet cooling hours. Is this a feasible
approach? Is there something else that I should be looking at?</span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;">Second
– Fan design KW/CFM – after reading through the archives I have
figured out that I just need to restore the defaults in the static in WG box to
allow the KW/CFM box to become active. Is the next step just to calculate the
bhp for each unit per table G3.1.2.9, then calculate fan power from section
G3.1.2.9? </span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;">I
did this for my first unit and got a value of .000768318 KW/CFM. This was for
system S1 with a baseline “design” (from the air side summary
report) CFM of 1,986 CFM. Does that seem like a reasonable #? I have
attached my calc spreadsheet for reference, it is a little crude but I think it
is correct. </span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;">Thanks
again in advance.</span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;">Travis</span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size: 11pt;"> </span></font></p>
</div></div></div>
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<br></blockquote></div><br><br clear="all"><br>-- <br>Carol Gardner PE<br>
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