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<title>Vav Boxes used for Dirty exhaust / return Systems </title>
<link>https://members.aabc.com/forums/posts.aspx?group=220211&amp;topic=1513944</link>
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<lastBuildDate>Sat, 13 Jun 2026 21:36:30 GMT</lastBuildDate>
<pubDate>Tue, 14 Sep 2021 20:52:10 GMT</pubDate>
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<title>Vav Boxes used for Dirty exhaust / return Systems </title>
<link>https://members.aabc.com/forums/posts.aspx?group=220211&amp;topic=1513944</link>
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<description><![CDATA[   It’s Edgar from Scotia Air Balance Ltd here in NS Canada.

Have a project that have vav boxes on the Exhaust / Return Systems . It’s 5 years since we did the TAB and we’re finding the Ex / Ret vav s are no longer calibrated . On inspection we found dirt / lint on the flow grids.

Just looking to see if this is a common issue ? Please see attached picture. There are some 600 boxes that are reading 30% low on the EMS over the actual flow . Creating issues with the further away boxes. Is there a filter system that could be used here so once they are cleaned we will not get the same issue in five more years .

Any advise would be appreciated.
Regards,
Edgar Nicholson TBS CET ]]></description>
<pubDate>Thu, 7 Nov 2019 19:47:52 GMT</pubDate>
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<link>https://members.aabc.com/forums/posts.aspx?group=220211&amp;topic=1581336</link>
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<description><![CDATA[if the maintenance or facility managements  department didn't make any duct cleaning regularly this defiantly will happen, that's why we didn't give any guarantee after TAB work complete more than 3 months.<br /><br />Best Regards,<br />Musab Abuowaimir]]></description>
<pubDate>Sun, 1 Nov 2020 10:34:26 GMT</pubDate>
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<link>https://members.aabc.com/forums/posts.aspx?group=220211&amp;topic=1586435</link>
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<description><![CDATA[They would probably need filters on all inlets at the face of the grilles to prevent debris from collecting and you may need to speed up the fan to account for filter drop /  loading. Same concept as filters in an AHU.]]></description>
<pubDate>Fri, 20 Nov 2020 18:28:20 GMT</pubDate>
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<title></title>
<link>https://members.aabc.com/forums/posts.aspx?group=220211&amp;topic=1632316</link>
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<description><![CDATA[I would take a look at the particle size and make up of the debris on the velocity sensors, then I would look at the filtration, especially the outside intakes, the MERV rating of the current filters may not be effective for the particle size.]]></description>
<pubDate>Tue, 14 Sep 2021 21:52:10 GMT</pubDate>
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