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<title>VAV with Electric Reheat</title>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Omar,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>You can try using a pre-heat coil as your hot water coil in the
air handler and the electric heat in your re-heat coil.<o:p></o:p></span></p>
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color:#1F497D'><o:p> </o:p></span></p>
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src="cid:image005.jpg@01CB28C3.471C1E70"></span><span style='font-size:11.0pt;
font-family:"Calibri","sans-serif";color:#1F497D'><o:p></o:p></span></p>
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font-family:"Calibri","sans-serif";color:#1F497D'><o:p></o:p></span></p>
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color:#1F497D'><o:p> </o:p></span></p>
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color:#1F497D'><o:p> </o:p></span></p>
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color:#1F497D'><o:p> </o:p></span></p>
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<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"'> Omar Katanani
[mailto:omar@ecoconsulting.net] <br>
<b>Sent:</b> Wednesday, July 21, 2010 10:06 AM<br>
<b>To:</b> Omar Katanani; equest-users@lists.onebuilding.org<br>
<b>Subject:</b> [Equest-users] VAV with Electric Reheat<o:p></o:p></span></p>
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<p style='margin-bottom:12.0pt'><span style='font-size:10.0pt'>Dear all,<br>
<br>
I'm sorry I've been nagging a lot lately, but believe me, you guys are my only
support!<br>
<br>
I was using a VAV system, with the reheat source being the hot water loop. I
specified the Reheat delta temperature by trial and error to 25F. Everything is
fine.<br>
<br>
Now I got updated info from the client saying that the source of the reheat is
electric. I am getting an error message:<br>
<br>
"Hot Water Loop has zero design flow. Check input for consistency,
or specify design loads."<br>
<br>
I read a couple of discussions. I understand that many factors will affect this
issue. The "Hot Deck Maximum Supply Temp", the "Reheat Delta
Temp", and the "Zone Entering Max Supply Temp".<br>
<br>
I tried specifying the hot deck max supply temp to 70F, I got the results
attached in the pdf. However, the gas consumption part of the space heating is
negligible compared to the electric, while I thought both will be of
significant ratios!<br>
<br>
My main question is how to get reasonable results, knowing that the main
heating source is the hot water loop, and the electric reheat is to fine tune
the temperature of zones experiencing different loads or so...<br>
<br>
I know that the design temperature of the zones is 70F, and that the
temperature that is supplied to the zone should be 30 degrees higher than the
zone temperature (70+30=100F).<br>
<br>
Any advice on how to choose the "reheat delta temp" and the "hot
deck maximum supply temp", or any other input parameter you feel that it
affects, is greatly appreciated.<br>
<br>
Many thanks,<br>
Omar<br>
___________________________<br>
<br>
Omar Katanani<br>
Sustainable Design Engineer<br>
Email: omar@ecoconsulting.net<br>
<br>
<br>
EcoConsulting (Lebanon)<br>
Nahas Building, 4th floor<br>
4 St-Maron Street / Georges Haddad Avenue<br>
Postal Code: 2028 5806 SAIFI<br>
Beirut, Lebanon<br>
Tel: +961 (0) 1 971 255<br>
Mobile: +961 (0) 3 045 045<br>
<br>
<br>
EcoConsulting (UK) Ltd<br>
28 Marshalsea Road<br>
London, SE1 1HF<br>
Tel: +44 (0)207 939 0989<br>
Fax: +44 (0)207 939 0981<br>
Website: www.ecoconsulting.net<br>
<br>
<br>
<br>
-----Original Message-----<br>
From: Omar Katanani<br>
Sent: Thu 7/15/2010 11:44 AM<br>
To: equest-users@lists.onebuilding.org<br>
Subject: VAV with Electric Reheat<br>
<br>
<br>
Dear all,<br>
<br>
I was using a VAV system, with the reheat source being the hot water loop. I
specified the Reheat delta temperature by trial and error to 20F. Everything is
fine.<br>
<br>
Now I got updated info from the client saying that the source of the reheat is
electric. I am getting an error message:<br>
<br>
"Hot Water Loop has zero design flow. Check input for consistency,
or specify design loads."<br>
<br>
I read a couple of discussions. I understand that many factors will affect this
issue. The "Hot Deck Maximum Supply Temp", the "Reheat Delta
Temp", and the "Zone Entering Max Supply Temp".<br>
<br>
First of all, is the sum of the first two equal to the third?<br>
<br>
My main question is how to get reasonable results, knowing that the main
heating source is the hot water loop, and the electric reheat is just to fine
tune the temperature of zones experiencing different loads or so...<br>
<br>
I played with all values but I can't figure out the pattern. I know that the
design temperature of the zones is 70F, and that the temperature that is
supplied to the zone should be 30 degrees higher than the zone temperature
(70+30=100F).<br>
<br>
Any advice on how to choose the "reheat delta temp" and the "hot
deck maximum supply temp" is greatly appreciated.<br>
<br>
Many thanks,<br>
Omar<br>
<br>
<br>
___________________________<br>
<br>
Omar Katanani<br>
Sustainable Design Engineer<br>
Email: omar@ecoconsulting.net<br>
<br>
<br>
EcoConsulting (Lebanon)<br>
Nahas Building, 4th floor<br>
4 St-Maron Street / Georges Haddad Avenue<br>
Postal Code: 2028 5806 SAIFI<br>
Beirut, Lebanon<br>
Tel: +961 (0) 1 971 255<br>
Mobile: +961 (0) 3 045 045<br>
<br>
<br>
EcoConsulting (UK) Ltd<br>
28 Marshalsea Road<br>
London, SE1 1HF<br>
Tel: +44 (0)207 939 0989<br>
Fax: +44 (0)207 939 0981<br>
Website: www.ecoconsulting.net<br>
<br>
<br>
</span><o:p></o:p></p>
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