[EnergyPlus_Support] Re: Airloop Error

["grandocu" <jgrando@xxxxxxxxxxxxx>]

I solved the issue.  The designer set the air handling unit's minimum outside air to a level much higher than what the zones were requesting.  Somehow between the zone:sizing and the specified minimum OA there was an error.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "James V Dirkes II, PE" <jim@...> wrote:
>
> Dear Phylroy,
> 
>  
> 
> The same operating schedule solves the issue if both fans operate
> continuously.  An OnOff fan does not, so if the Exhaust fan is running
> during an Off cycle of the zone fan, you get a warning.
> 
>  
> 
> The Building Performance Team
> James V. Dirkes II, P.E., LEED AP
> 1631 Acacia Drive NW
> Grand Rapids, MI 49504
> 616 450 8653
> 
>  
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Phylroy Lopez
> Sent: Monday, September 27, 2010 12:15 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: Re: [EnergyPlus_Support] Airloop Error
> 
>  
> 
>   
> 
> Wouldn't having the same operating schedule for the supply and exhaust fans
> solve this problem?
> 
> Sent from my iPhone
> 
> 
> On 2010-09-24, at 2:23 PM, Vinay Devanathan <vinay.devanathan@...>
> wrote:
> 
>   
> 
> Mr. Dirkes,
> 
> I have been having this problem too and I would like to know if there is any
> way to correct this warning (occurring because of points 2 & 3  as mentioned
> by you). 
> 
> Thank you.
> 
> Regards,
> Vinay
> 
> On Fri, Sep 24, 2010 at 1:54 PM, James V Dirkes II, PE
> <jim@...> wrote:
> 
>   
> 
> Here are a couple of things to consider:
> 
> .         You must have an exhaust fan in the zone.  Its airflow rate must
> match the amount of outdoor air introduced to the zone by each air loop.
> Normally that zone outdoor airflow rate is controlled in the
> Controller:OutdoorAir object, but it is also influenced by the outdoor air
> fields in Sizing:Zone. If you have an ERV or other zone object which
> introduces outdoor air, that also affects the balance.
> 
> .         If your zone fan is not operating at the exact same times as the
> exhaust fan(s), the "unbalanced exhaust" message will occur when the zone
> fan is off (and exhaust is on)
> 
> .         Finally if your zone fan is the OnOff style, the warning will
> occur during times that the zone fan cycles off and the exhaust fan remains
> on.
> 
>  
> 
>  
> 
> p.s., Most of this information is from having the same problem and getting
> excellent assistance from Mike Witte 
> 
>  
> 
> The Building Performance Team
> James V. Dirkes II, P.E., LEED AP
> 1631 Acacia Drive NW
> Grand Rapids, MI 49504
> 616 450 8653
> 
>  
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of grandocu
> Sent: Friday, September 24, 2010 10:52 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Airloop Error
> 
>  
> 
>   
> 
> Hello,
> 
> I'm getting the following error:
> 
> ** Warning ** In AirLoopHVAC AHU-B-5 there is unbalanced exhaust air flow.
> ** ~~~ ** During Warmup, Environment=SUMMERSIZINGDAY, at Simulation
> time=07/20 19:40 - 19:50
> ** ~~~ ** Unless there is balancing infiltration / ventilation air flow,
> this will result in
> ** ~~~ ** load due to induced outdoor air being neglected in the simulation.
> 
> I don't see a problem with my connections but I did supply airflow rate
> myself. I am also getting a "maximum iterations" error for this airloop. Has
> anyone ever had this problem before? Thank you.
>




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