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<font face="Times New Roman, Times, serif"> With your air flow and
heat load you need a differential temperature</font> of 23.7F to remove
the 300kW of heat from the room. With a set point in the pump room of
90F your economizer will be at 100% OA at about 66F OA temp, this
approximately the temperature you want for the cooling coil to take
over and Equest will switch it over, you don't need to schedule that.
With your economizer low end temp set to 55 you have nothing happening
below 55F, equest has the economizer shut off. You say you also have
the cooling coil off. This is where you are probably getting the
insufficient cooling warning. You don't need to schedule the
economizer proportions, equest will do that on its own in the
temperature ranges you allow it to operate. Equest will want to supply
around 66F air to the pump room. Your minimum supply temperature won't
do anything in this situation. Take a copy and set the economizer low
end cut-off temperature to 0F. That should get rid of your warning at
least down to 0F anyway. Equest will probably allow you to freeze the
coil, it would assume you have a glycol mix to prevent this. In
reality you don't but the solution may be to drain the coil in the
winter and run the economizer at all temperatures below 66F. Water
loops can be tricky as well judging from some of the difficulties
others have talked about in posts, make sure you have pump flow in the
water loop. You also have to watch your water supply, small ponds will
heat as the summer progresses raising your incoming water temperature.
Now if you are drawing water from Lake Ontario below the thermocline
you should have a consistent EWT to your coil. I have not done a loop
like this in Equest but it seems that it is working in your model.<br>
<font color="black" face="Times New Roman" size="3"><span
style="font-size: 12pt;">Bruce Easterbrook P.Eng.<br>
Abode Engineering</span></font><br>
<br>
On 03/08/2010 10:32 AM, Kevin Kyte wrote:
<blockquote
cite="mid:7F7FF64673C26D4DA4A62094657BD91403F5916933@wattsexch.wattsae.local"
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<div class="Section1">
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;">The current
controls are when outside air is
below 55F the cooling coil shuts down, there is no supplemental cooling
only
lake water. Therefore the outside air and return air must modulate to
maintain 55F supply air temp. With 300 kW of internal gain and 40000
CFM supply
airflow, SS-F shows up to 200F in the space at minimum outside air
below
55F. We considered letting the lake water coil run at all temperatures
though
don’t want to risk freezing the coil. I understand that if we run
the coil in the winter time and just return air it would probably save
on fan
energy. The coil is probably efficient enough and the thought is the
main
water line will have enough pressure to branch off and circulate
through the coil
loop without additional pumping at all times.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;">Considering
the current design strategy, I
think the only way to accuracy model the OA and RA modulation is to
schedule it
in the min-OA schedule. I have set a min-supply-T so the software
should
use that as a minimum supply air temperature but I notice that when
economizing,
at least with no low limit, the min-supply-T entry gets thrown into the
garbage
(yet we still get the warning). Is there any way to program it in
using
expressions? Not sure which entry though, maybe min-air-schedule?
Above 55F, since 100% OA is used, the cooling coil is only used when
lake water
temp is below outside air temp. There is no way to model this however,
except
fiddling with the cool-control range, which is entirely inaccurate. I
think the economizer should be integrated with coil because they are
both used simultaneously,
at least in the current control scheme. You might be able to get away
with the delta T just using return air, I haven’t done the calc though.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;">The model is
pretty much done, I think,
and I was hoping to get some feedback from the board on this warning.
Something that I am not seeing? <o:p></o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;">Thank you.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;">Kevin<o:p></o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"><o:p> </o:p></span></font></p>
<div>
<div class="MsoNormal" style="text-align: center;" align="center"><font
color="black" face="Times New Roman" size="3"><span
style="font-size: 12pt; color: windowtext;">
<hr tabindex="-1" align="center" size="2" width="100%"></span></font></div>
<p class="MsoNormal"><b><font color="black" face="Tahoma" size="2"><span
style="font-size: 10pt; font-family: Tahoma; color: windowtext; font-weight: bold;">From:</span></font></b><font
color="black" face="Tahoma" size="2"><span
style="font-size: 10pt; font-family: Tahoma; color: windowtext;">
Bruce Easterbrook [<a class="moz-txt-link-freetext" href="mailto:bruce5@bellnet.ca">mailto:bruce5@bellnet.ca</a>] <br>
<b><span style="font-weight: bold;">Sent:</span></b> Monday, August
02, 2010 4:47
PM<br>
<b><span style="font-weight: bold;">To:</span></b> <st1:personname
w:st="on">Kevin Kyte</st1:personname><br>
<b><span style="font-weight: bold;">Cc:</span></b> <st1:personname
w:st="on">'eQUEST Users List'</st1:personname><br>
<b><span style="font-weight: bold;">Subject:</span></b> Re:
[Equest-users] an
inadequate cooling capability warning</span></font><font color="black"><span
style="color: windowtext;"><o:p></o:p></span></font></p>
</div>
<p class="MsoNormal"><font color="black" face="Times New Roman"
size="3"><span style="font-size: 12pt;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font color="black" face="Times New Roman"
size="3"><span style="font-size: 12pt;"> I think your control
strategy is
not right or you are misinterpreting how equest works. You say your
room
requires cooling at all times of the year and you want to keep your
maximum
temperature below 104F. You have selected 90F as your control point
which
is the setting of your room t-stat. Your 55F temperature only matters
if
you have potentially freezing temperatures in the winter because you
have a
water coil which you don't want to freeze. Below 55 your economizer is
shut off and you should be on minimum fresh air which with no personnel
in the
pump room should be at .06 cfm/SF, you will be almost at 100% return
air.
You should have a differential temperature or enthalpy controller to
control
the economizer. Your system will remain like this, considering std
equest
defaults until the room temperature reaches 92 F. If the outside air
temperature is above 55 the system will use the economizer to control
the
temperature. If that fails it will use the cooling coil. You don't
want both the economizer and the cooling cool running at the same
time.
Basically you don't want to use water pumping energy if you don't have
to as it
is additional energy on top of the fan. Practically you could have 2
temperature controllers controlling part of the same air stream and the
system
will hunt. The only other variable here is the water temperature in
the
summer. Basically your peak heat generation in the pump room and your
peak water temperature in the summer will set your system CFM, coil
size, coil
flow, pump size. This is a basic explanation, there are more things to
play with to fine tune the system further.<br>
Bruce Easterbrook P.Eng.<br>
Abode Engineering<br>
<br>
On 02/08/2010 03:09 PM, <st1:personname w:st="on">Kevin Kyte</st1:personname>
wrote: <o:p></o:p></span></font></p>
<p class="MsoNormal"><font color="black" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><u1:smarttagtype
namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="PostalCode"><u1:smarttagtype
namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="State"><u1:smarttagtype
namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="City"><u1:smarttagtype
namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="Street"><u1:smarttagtype
namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="address"><u1:smarttagtype
namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place">I
have
been struggling with this scenario. A pump room does not need to
exceed 104F. <st1:place u2:st="on"><st1:place w:st="on">Lake</st1:place></st1:place>
water is used for cooling. The room is expected to contain internal
loads
requiring cooling at almost all times. Below 55F the OA and RA
modulate
to provide 55F supply air. Above 55F, 100% OA and the cooling coil
turns
on. I have the cooling Tstat set to 90F and cooling coil available at
55F. I am unsure how to even model Below 55F except for economizing
which
is not really exact but when I set the economizing low limit to 55F I
get 200F
in the space. I have set economizing to 90F integrated with the coil
and
no low limit. The cooling coil is rarely used and not needed in its
full
capacity yet I am getting inadequate cooling warnings. <u1:p></u1:p></u1:smarttagtype></u1:smarttagtype></u1:smarttagtype></u1:smarttagtype></u1:smarttagtype></u1:smarttagtype></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">The Min-Supply-T is set
to 55F because supply should
not be less than this and hourly reports show acceptable supply
temperatures
into the mid 70s (I don’t know if this is acceptable to the
program?) I am not using a lake water chiller because I am not trying
to
use the same coil temperature. I am using a simple packaged single
zone
with the cool-control range set to max and EIR zero’d because there is
enough force off the main header to not need any pumping through the
loop.<u1:p></u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">This is only for energy
code compliance and I need an
explanation on the warnings. Other than stating several obvious
limitations I don’t really understand why this warning is occurring.
Does anyone have suggestions on how I may model this system?<u1:p></u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">I understand that
electronic files would help and I
will work on that.<u1:p></u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">Thank you.<u1:p></u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class="MsoAutoSig"><st1:personname w:st="on"><font color="black"
face="Times New Roman" size="3"><span style="font-size: 12pt;">Kevin
Kyte</span></font></st1:personname>,
<font size="2"><span style="font-size: 10pt;">LEED</span></font><sup><font
face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"> </span></font></sup><sup><font
size="2"><span style="font-size: 10pt;">®</span></font></sup><font
size="2"><span style="font-size: 10pt;"> AP<u1:p></u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><st1:place u2:st="on"><st1:place w:st="on"><b><font
color="black" face="Times New Roman" size="3"><span
style="font-size: 12pt; font-weight: bold;">Watts</span></font></b></st1:place></st1:place><b><span
style="font-weight: bold;"> Architecture & Engineering, P.C.<u1:p></u1:p></span></b><o:p></o:p></p>
<p class="MsoNormal"><st1:street u2:st="on"><st1:address u2:st="on"><st1:street
w:st="on"><st1:address w:st="on"><font color="black" face="Shruti"
size="2"><span style="font-size: 10.5pt; font-family: Shruti;">95
Perry Street, Suite 300</span></font></st1:address></st1:street></st1:address></st1:street><o:p></o:p></p>
<u1:p></u1:p>
<p class="MsoNormal"><st1:place u2:st="on"><st1:city u2:st="on"><st1:place
w:st="on"><st1:city w:st="on"><font color="black" face="Shruti"
size="2"><span style="font-size: 10.5pt; font-family: Shruti;">Buffalo</span></font></st1:city><font
face="Shruti" size="2"><span
style="font-size: 10.5pt; font-family: Shruti;"></span></font></st1:place><font
face="Shruti" size="2">, <st1:state u2:st="on"><st1:state w:st="on">NY</st1:state></st1:state>
<st1:postalcode u2:st="on"><st1:postalcode w:st="on">14203</st1:postalcode></st1:postalcode></font></st1:city></st1:place><o:p></o:p></p>
<u1:p></u1:p>
<p class="MsoNormal"><font color="black" face="Shruti" size="2"><span
style="font-size: 10.5pt; font-family: Shruti;">p: 716.206.5174<u1:p></u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Shruti" size="2"><span
style="font-size: 10.5pt; font-family: Shruti;">f.: 716.206.5199<u1:p></u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Times New Roman"
size="2"><span style="font-size: 11pt;">e: <a
href="mailto:kkyte@watts-ae.com" moz-do-not-send="true">kkyte@watts-ae.com</a><u1:p></u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Times New Roman"
size="2"><span style="font-size: 11pt;"><a
href="http://www.watts-ae.com/" moz-do-not-send="true">http://www.watts-ae.com</a><u1:p></u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Times New Roman"
size="2"><span style="font-size: 11pt;"><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class="MsoNormal"><font color="black" face="Times New Roman"
size="3"><span style="font-size: 12pt;"><u1:p> </u1:p><o:p></o:p></span></font></p>
<p class="MsoNormal"><font color="black" face="Times New Roman"
size="3"><span style="font-size: 12pt;"><u1:p> </u1:p><o:p></o:p></span></font></p>
<pre wrap=""><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;"><o:p> </o:p></span></font></pre>
<pre><fieldset class="mimeAttachmentHeader"></fieldset><font
color="black" face="Courier New" size="2"><span
style="font-size: 10pt;"><o:p> </o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;">_______________________________________________<o:p></o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;">Equest-users mailing list<o:p></o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;"><a moz-do-not-send="true"
href="http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org">http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org</a><o:p></o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;">To unsubscribe from this mailing list send a blank message to <a
moz-do-not-send="true"
href="mailto:EQUEST-USERS-UNSUBSCRIBE@ONEBUILDING.ORG">EQUEST-USERS-UNSUBSCRIBE@ONEBUILDING.ORG</a><o:p></o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;"> <o:p></o:p></span></font></pre>
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