<div>Hi Omar,</div>
<div> </div>
<div>At least your life is normal with having to do some sim runs last minute for your engineers, and they think it is easy for you...</div>
<div> </div>
<div>This is not an easy thing to do with one day notice....based on my one time experience with modeling a VRV system.</div>
<div> </div>
<div>What I learned from modeling my VRV model was this:</div>
<ol>
<li>One it is critical to know the Mfg (or use a sample Mfg as a place holder until they specify which Mfg will be used). I learned from speaking with a Mitsubishi rep that the Mfg will be able to give you the specific performance data that you need for thier equipment. When I used the Mfg data provided to me for the project units that were specified the energy efficiency of the VRV systems could be demonstrated in eQuest better than just using the 90.1 baseline performance #'s.<br>
(The advantage to using VRV systems is that they are SUPER HIGH efficiency compared to other HVAC systems types including hydronic systems. These are the new premium efficiency systems that are being chosen for more and more designs lately.)</li>
<li>There were two numbers that I received from the Mfg for each of the equipment models that were being installed. He gave me a new EIR number to input for the dx cooling input, and he gave me a new fan power number. After inputting these manufacturer-provided data, this is when I really saw the drop in energy use in my proposed model---YAY!</li>
<li>I attempted to input custom curves for the equipment, but I was under a time crunch and I couldn't get them to work, so I had to go with only the partial estimate of energy savings (without the effect of the part-load curves.) If I could have taken more time to work on the specific curve data then I know I could have shown even more savings than what I was seeing with the two previous inputs.</li>
<li>It is best to use the system type of "PVVT" (pkg vari vol & temp) system. This system has a check box in eQuest to select <u>variable speed compressor.</u> This option is not available in other system types which makes this system choice the best representation for a real-life VRV heat pump system.</li>
</ol>
<div>I will also forward you a file of a presentation done a few years ago that has some guidance info on how to perform VRV system inputs into eQuest. This will help get you going on your analysis.</div>
<div> </div>
<div>In my case I was happy that I could show a good chunck of energy savings with only the first 2 inputs...at least I could show my client that "yes, your choice for VRV systems will offer higher energy savings." It was better for me to be able to show some energy savings with my inputs as opposed to not being able to demonstrate any savings because eQuest (and other sim programs) cannot accurately perform simulations for VRV systems. In this case, my client was happy (& content) with seeing 'some rather than none.' I just explained to them that there are limitations in simulation software to do this, but a good educated "guesstimate" from eQuest was better than nothing.</div>
<div> </div>
<div>I don't think that you will be able to complete this analysis before your meeting, but you can let your client know that you are working on the analysis and this type of system is difficult to represent in our current software packages available.</div>
<div> </div>
<div>I know other simulators on this list have more experience with VRV systems than I do, so maybe do a search in the eQuest archives for more discussions on VRVs.</div>
<div> </div>
<div> </div>
<div>Hope this helps, good luck.</div>
<div> </div>
<div>Pasha</div>
<div> </div>
<div> </div>
<div class="gmail_quote">On Wed, Oct 6, 2010 at 2:33 PM, Omar Katanani <span dir="ltr"><<a href="mailto:omar@ecoconsulting.net">omar@ecoconsulting.net</a>></span> wrote:<br>
<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote">
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<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt">Dear all,</span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt">I have a meeting with the Mechanical engineers tomorrow, and one of the topics to be discussed is VRVs.</span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt">The HVAC strategy was VAV for all the school, with FCU’s for 15 specified zones. </span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt">An update to the design changed 4 of these 15 zones into a VRV system (I do not know why they decided on this!)</span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt">So I must now model these zones with VRV systems.</span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt">My urgent questions that may require further discussion with the Mechanical design engineers are:</span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt"> </span></font></p>
<ol type="1">
<li class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt">I think I must know the performance curves of the VRV system. However, the final choice of the VRV brand is not finalized, and I may need to assume a typical performance curve. Any idea on which curve to use?</span></font></li>
<li class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt">I have the EER of the VRV system to be 10. Where should I enter this? Is it that I need to create a separate chiller for the VRVs with an EER of 10?</span></font></li>
<li class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt">What additional important input variables do I need from the design team? (zone supply air flow rate, outdoor air flow rate)</span></font></li>
</ol>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt">Many thanks for your kind help!</span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt">Best regards,</span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span style="FONT-FAMILY: Arial; FONT-SIZE: 10pt">Omar</span></font></p>
<p class="MsoNormal"><font color="navy" size="2" face="Arial"><span style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt">___________________________</span></font></p>
<p class="MsoNormal"><font color="navy" size="2" face="Arial"><span style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt">Omar Katanani<br>Sustainable Design Engineer</span></font></p>
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