[Equest-users] Dual Duct VAV problems

[Bryce Munger]

Sorry, I should have explained further.  I am trying to simulate a sequence of measures, one of which is adding variable speed control to the ahu fan for the dual duct system.  That is the measure with the problem.  A dual fan dual duct system with VAV control on the system fans works fine and the SS-L report shows the fan power varying while the single duct system won’t vary unless I take the 100% OA requirement out and add occupancy OA control at the zone level.  Why can’t I make a single fan dual duct system have a VFD on the main ahu fan?

 

Bryce

 

From: John Aulbach [mailto:jra_sac at yahoo.com] 
Sent: Tuesday, February 01, 2011 10:58 AM
To: Bryce Munger; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Dual Duct VAV problems

 

Bryce:

 

Forgive my systems ignorance. But if you have a single fan dual duct system, don't the hot and cold deck dampers just swing from heating to cooling? How will the airflow vary unless you have two fans?

 

I can learn as well from our well versed members.

 

 

John R. Aulbach, PE, CEM

Senior Energy Engineer

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Partner Energy

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www.ptrenergy.com <http://www.ptrenergy.com/>  | jaulbach at ptrenergy.com <mailto:%7C%20jaulbach at ptrenergy.com> 

 

 

 

________________________________

From: Bryce Munger <BMunger at glumac.com>
To: equest-users at lists.onebuilding.org
Sent: Tue, February 1, 2011 10:46:02 AM
Subject: [Equest-users] Dual Duct VAV problems

I am working on a dual duct simulation and I am having trouble getting vav control to work correctly.  The system is defined as a 100% OA Dual Duct Single Fan system and I  have tried everything I can think of to get the fans to vary.  When the sim runs, the fans are pegged in the 90-100% range all year.  When I change to a dual fan dual duct system, the fans will act as a vav fan is expected with a range of operating hours throughout the year.  I have tried Fan Control of “Variable Speed” and “Fan EIR FPLR”  without success.    Any ideas?

 

Thanks, 

 

Bryce

 

 

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