[EnergyPlus_Support] Re: Warning Message: air volume flow per cooling capacity out of range

["bcmcgr" <bcmcgr@xxxxxxxxx>]

Thanks James.

I don't know if you remember but I took a class taught by you and Mahabir in DC a while back.

Alright, I think I've found a solution - I can change the "Zone Airflow" -> "ZoneInfiltration:DesignFlowRate" to make the (m3/s)/W fall within the range stipulated by E+. Is this a sound solution to my problem? As I see it, it let's me keep my actual system capacities while only changing the supply flow rate.

Brendan

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "James V Dirkes II, PE" <jim@...> wrote:
>
> Dear Brendan,
> 
>  
> 
> "Autosize" and "Proposed" don't go together in ASHRAE 90.1.
> 
>  
> 
> I think you'll need something reasonably close to actual design, perhaps
> with an explanation of the E+ limitations as they affect your DX coil.
> 
>  
> 
> 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 bcmcgr
> Sent: Thursday, February 10, 2011 10:41 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Re: Warning Message: air volume flow per
> cooling capacity out of range
> 
>  
> 
>   
> 
> That's what I'm finding as well.
> 
> Do either of you know if LEED will accept my model with the Proposed case's
> heating and cooling capacities being autosized?
> 
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> , "James V Dirkes II, PE"
> <jim@> wrote:
> >
> > Brendan,
> > 
> > 
> > 
> > E+ has limits for flow / Watt which show up in the .err file. I think they
> > vary a bit depending on the coil, but generally flow / Watt must be:
> > 
> > 
> > 
> > >0.00004027 and <0.00006041
> > 
> > 
> > 
> > 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%40yahoogroups.com> 
> > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> ] On Behalf Of bcmcgr
> > Sent: Thursday, February 10, 2011 9:26 AM
> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> 
> > Subject: [EnergyPlus_Support] Re: Warning Message: air volume flow per
> > cooling capacity out of range
> > 
> > 
> > 
> > 
> > 
> > Thank you both for your prompt help. It is definitely appreciated.
> > 
> > Can either of you explain to me how you "ensure that the maximum supply
> flow
> > is changed accordingly". I can definitely change the max to design
> > conditions but I'm not sure how to do this in either E+ or DB.
> > 
> > Thanks again.
> > 
> > Brendan
> > 
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> 
> > <mailto:EnergyPlus_Support%40yahoogroups.com> , "James V Dirkes II, PE"
> > <jim@> wrote:
> > >
> > > Dear Brendan,
> > > 
> > > 
> > > 
> > > The airflow / watt warning is a common one for me, also, for manually
> > sized
> > > systems.
> > > 
> > > 
> > > 
> > > I have not tried it yet, but the E+ Help desk suggested that I put two
> > coils
> > > in series to eliminate the warning. This effectively will leave the
> > airflow
> > > the same but cuts the coil capacity in half for each coil. it might
> work!
> > > 
> > > 
> > > 
> > > p.s., This fix will probably not significantly affect your results
> unless
> > > you have accurate part load curve information for your coils. If you DO
> > > have that information, you may be able to cobble some part load
> > coefficients
> > > (different for each coil) that will do the trick.
> > > 
> > > 
> > > 
> > > 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%40yahoogroups.com> 
> > <mailto:EnergyPlus_Support%40yahoogroups.com> 
> > > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> 
> > <mailto:EnergyPlus_Support%40yahoogroups.com> ] On Behalf Of bcmcgr
> > > Sent: Wednesday, February 09, 2011 2:15 PM
> > > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> 
> > <mailto:EnergyPlus_Support%40yahoogroups.com> 
> > > Subject: [EnergyPlus_Support] Warning Message: air volume flow per
> cooling
> > > capacity out of range
> > > 
> > > 
> > > 
> > > 
> > > 
> > > "Rated air volume flow rate per watt of rated total cooling capacity is
> > out
> > > of range."
> > > 
> > > I'm working on a LEED project using Design Builder and my Proposed model
> > > gets the above "Severe Error" when the model is run in E+. I can get
> > around
> > > this by having Design Builder "autosize" my HVAC system but then when I
> > > check the HVAC system sizing output from E+ my sizes (capacities) are
> much
> > > less than the actual design. 
> > > 
> > > It's important to note here that I'm modeling the minimum ventilation
> > > (outside air) per ASHRAE 62.1 (ie per person and per area) which is much
> > > smaller than the capabilities of the system. 
> > > 
> > > Has anyone encountered this in the past? Should I just submit the model
> as
> > > if it's autosized? 
> > > 
> > > And, of course, I'm being rushed to submit by Friday. Any help on this
> is
> > > much appreciated.
> > > 
> > > Thanks in advance. 
> > > 
> > > Brendan
> > >
> >
>




------------------------------------

Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx

The primary EnergyPlus web site is found at:
http://www.energyplus.gov

The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/

Attachments are currently allowed but be mindful that not everyone has a high speed connection.  Limit attachments to small files.

EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
Yahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/

<*> Your email settings:
    Individual Email | Traditional

<*> To change settings online go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/join
    (Yahoo! ID required)

<*> To change settings via email:
    EnergyPlus_Support-digest@xxxxxxxxxxxxxxx 
    EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx

<*> To unsubscribe from this group, send an email to:
    EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx

<*> Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/