<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<font size="+1"><tt>I haven't done a VRF system so my remarks apply
to trying to get multiple zones under control using a single
thermostat. The biggest problem is you probably do not have
enough airflow to begin with to carry the heat required. The
eQuest default is 0.5 chm/SF. Once you get into heating
dominated climates this is not nearly enough air to accomplish
your heating with the air handler. eQuest will size your
airflow to handle the cooling demand which it has done in your
case but leaves you with some pretty extreme under heated
hours. Start bringing up your cfm/SF up in 5% increments
starting at 1.0 cfm/SF. Monitor your heating capacity of your
air handler(s) on the SV-A page. The SS-J heating peaks will
also start to increase. Once you aren't getting any change in
your heating capacity of the system air handler you have gone
far enough and may need to backtrack a bit. You can adjust your
throttling range a bit say to 4 deg instead of 2. You can
adjust your control zone, or the location of your T-stat to see
if you can find a better location. Your main tool is the
cfm/SF. In my area, much colder than Oregon I get into the 1.2
to 1.25 cfm/SF range. On one I just did the under heated hours
per zone went from the 900-1000 hour range down to 40 to 180
hours for some of the trouble zones with a majority in the 0 to
10 hour range. Then I added in the baseboards and all the under
heat hours vanished. You don't want to use the baseboards for
control too fast as you want to have your AHU carry the majority
of the load because your AHU will typically use gas to heat and
your baseboards will use electricity. I think this will work
with either work around for VRF. You have a heat coil and a
cooling coil each at a specific temperature. The only other
variable you have to heat or remove heat from your zone is your
airflow. So eQuest has provided your maximum airflow required
for cooling at around 0.5 cfm/SF, it will adjust the flows to
different zones, your increased airflow for heating will give
you the approximate maximum flows required for heating. So you
have basically sized your terminal unit flow. With your maximum
heating and cooling effects all on the AHU you will get a better
picture of what your work around system will have to handle.
Excessive heating with the baseboards could give you a false
picture if you are not careful, you just want them for trimming
to get your errors to disappear and hopefully most of your
warnings. They do provide the heating differentials from the
control zone. The SV-A will also give you a good picture of
what is happening in each zone. Other reports will help you
track down trouble zones, what is happening and hopefully why.<br>
Bruce Easterbrook P.Eng.<br>
Abode Engineering<br>
</tt></font><br>
On 12/01/2012 04:21 PM, Neil Bulger wrote:
<blockquote
cite="mid:E9AD575374574E439EA4C93EC054103A80F65493E9@vesuvius2.rumseyengineers.com"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=ISO-8859-1">
<meta name="Generator" content="Microsoft Word 12 (filtered
medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:"Bradley Hand ITC";
panose-1:3 7 4 2 5 3 2 3 2 3;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p.MsoAcetate, li.MsoAcetate, div.MsoAcetate
{mso-style-priority:99;
mso-style-link:"Balloon Text Char";
margin:0in;
margin-bottom:.0001pt;
font-size:8.0pt;
font-family:"Tahoma","sans-serif";}
span.EmailStyle17
{mso-style-type:personal;
font-family:"Calibri","sans-serif";
color:windowtext;}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
span.BalloonTextChar
{mso-style-name:"Balloon Text Char";
mso-style-priority:99;
mso-style-link:"Balloon Text";
font-family:"Tahoma","sans-serif";}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
<div class="WordSection1">
<p class="MsoNormal"><span style="color:#1F497D">Hi Loi,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I have run
across this as well with trying to model VRV in eQuest. PVVT
is a difficult system to work with because it requires
specifying 1 zone as the thermostat that drives the whole
system. Therefore, 1 zone will drive what supply air
temperature the central AHU delivers to each zone. This can
make hours out of range on cooling difficult but, if heating
is the issue you may have more flexibility with zone-level
heating options (reheat or baseboards). However, that can
start to look strange when in reality, these features do not
exist. But, the hours out of range typically stem from this
single-zone-thermostat issue with PVVT.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Another
approach I have not perfected yet that I thought of was to
try using the eQuest Water Heat Pump system. The Water Heat
Pump ties to a WLHP water-loop (it appears yellow in the
Water-Side tab). If you were to place a dry-cooling tower on
this loop, effectively, the dry cooling tower would be (in
my mind) the same as an air-source condenser, like we would
see in reality with a VRV system (typically).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">This may be
good or bad on the airside in eQuest (I am hoping good) in
that it provides another set of options and heat flow
control at each system. Again, I have not dug into how this
would go together best and I would imagine some post
processing would be needed to understand the results.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Would love to
hear any other creative ideas out there for VRV
work-arounds.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<div>
<p class="MsoNormal"><b><span
style="font-size:8.5pt;font-family:"Arial","sans-serif";color:gray">Neil
Bulger</span></b><span style="color:gray"><br>
</span><span
style="font-size:8.5pt;font-family:"Arial","sans-serif";color:gray">Project
Engineer<o:p></o:p></span></p>
<p class="MsoNormal"><b><span
style="font-size:8.5pt;font-family:"Arial","sans-serif";color:#99CC00">________________________________</span></b><span
style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-family:"Arial","sans-serif";color:#999999">I
N T E G R A L<o:p></o:p></span></p>
<p class="MsoNormal"><b><span
style="font-size:8.5pt;font-family:"Arial","sans-serif";color:#999999">
</span></b><b><span
style="font-size:8.5pt;font-family:"Arial","sans-serif";color:gray"> </span></b><b><span
style="font-size:8.0pt;font-family:"Arial","sans-serif";color:gray">GROUP</span></b><span
style="font-size:8.0pt;font-family:"Times New
Roman","serif";color:gray"><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:8.5pt;font-family:"Arial","sans-serif";color:#999999"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-bottom:6.0pt"><span
style="font-size:8.5pt;font-family:"Arial","sans-serif";color:gray">427 13th Street,
Oakland CA 94612</span><span style="color:gray"><br>
</span><span
style="font-size:8.5pt;font-family:"Arial","sans-serif";color:gray">510
663 2070 x 235<br>
</span><span style="color:#1F497D"><a moz-do-not-send="true"
href="mailto:nbulger@integralgroup.com"><span
style="font-size:8.5pt;font-family:"Arial","sans-serif"">nbulger@integralgroup.com</span></a></span><span
style="font-size:8.5pt;font-family:"Arial","sans-serif";color:gray"><br>
</span><span style="color:#1F497D"><a moz-do-not-send="true"
href="http://www.integralgroup.com/"><span
style="font-size:8.5pt;font-family:"Arial","sans-serif"">www.integralgroup.com</span></a></span><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif";color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><b><span
style="font-size:8.0pt;color:#99CC00">DEEP GREEN
Engineering.<o:p></o:p></span></b></p>
<p class="MsoNormal" style="margin-bottom:6.0pt"><b><span
style="font-size:8.5pt;font-family:"Arial","sans-serif";color:#99CC00">________________________________<o:p></o:p></span></b></p>
</div>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0in 0in 0in">
<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"">
<a class="moz-txt-link-abbreviated" href="mailto:equest-users-bounces@lists.onebuilding.org">equest-users-bounces@lists.onebuilding.org</a>
[<a class="moz-txt-link-freetext" href="mailto:equest-users-bounces@lists.onebuilding.org">mailto:equest-users-bounces@lists.onebuilding.org</a>] <b>On
Behalf Of </b>Loi Ng<br>
<b>Sent:</b> Thursday, January 12, 2012 9:38 AM<br>
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:equest-users@onebuilding.org">equest-users@onebuilding.org</a><br>
<b>Subject:</b> [Equest-users] Help - Modeling VRV-VRF
System with eQuest<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am modeling VRV system based on a “Energy
Trust of Oregon, Inc.” guidance document (attached) posted by
Mathew Larson of Colorado dated 12/12/2011. The document
recommends using a PVVT system to simulate a VRV system. I
used an air cooled PVVT system to model a VRV system.
However, the unmet hours on the heating is very high. The
cooling part is okay. Does anyone has experience on bringing
down the unmet hours?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks! <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><b><span
style="font-size:14.0pt;font-family:"Bradley Hand
ITC"">Loi Ng<o:p></o:p></span></b></p>
<p class="MsoNormal"><span
style="font-size:9.0pt;font-family:"Arial","sans-serif"">Mechanical
Engineer</span><span
style="font-size:12.0pt;font-family:"Arial","sans-serif"">,
</span><span
style="font-size:9.0pt;font-family:"Arial","sans-serif"">LEED<sup>®</sup>
AP</span><span
style="font-size:12.0pt;font-family:"Arial","sans-serif""><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:9.0pt;font-family:"Arial","sans-serif";color:#0070C0">Diversified
Engineering, Inc.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:9.0pt;font-family:"Arial","sans-serif";color:#0070C0">914
Silver Spring Avenue, Suite 208<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:9.0pt;font-family:"Arial","sans-serif";color:#0070C0">Silver
Spring, MD 20190<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:9.0pt;font-family:"Arial","sans-serif";color:#0070C0">Tel:
301-565-2000 x 234<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:9.0pt;font-family:"Arial","sans-serif";color:#0070C0">Fax
301-495-1563 <o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Equest-users mailing list
<a class="moz-txt-link-freetext" href="http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org">http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org</a>
To unsubscribe from this mailing list send a blank message to <a class="moz-txt-link-abbreviated" href="mailto:EQUEST-USERS-UNSUBSCRIBE@ONEBUILDING.ORG">EQUEST-USERS-UNSUBSCRIBE@ONEBUILDING.ORG</a>
</pre>
</blockquote>
</body>
</html>