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

["bcmcgr" <bcmcgr@xxxxxxxxx>]

James,

Basically what I was asking was that if I could just change the  "Zone Airflow" -> "ZoneInfiltration:DesignFlowRate" to make the (m3/s)/W fall within the range stipulated by E+. In the E+ idf file that is the only location that I can find to change the supply flow. It seems to be where E+ pulls it from DB. 

I was able to change those values iteratively to get within the range and keep my heating and cooling capacities at actual size.

Is there another place within E+ to modify the "supply air flow rate"?


Brendan

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "James V Dirkes II, PE" <jim@...> wrote:
>
> Dear Brendan,
> 
>  
> 
> There is a bell ringing faintly in the back of my head about "Brendan" from
> the DB class, but I can't put a face to the name (or a last name, either).
> 
>  
> 
> I'm glad, nonetheless, that you're still working with DB and E+!
> 
>  
> 
> On to the tech issue..
> 
>  
> 
> I don't understand what you are saying, so you'll need to elaborate a bit.
> 
>  
> 
> All I can tell you at the moment is that the Zone airflow will probably
> never equal the zone infiltration unless you are modeling a tent . but you
> probably didn't mean that.
> 
>  
> 
> 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 12:12 PM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Re: Warning Message: air volume flow per
> cooling capacity out of range
> 
>  
> 
>   
> 
> 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
> <mailto:EnergyPlus_Support%40yahoogroups.com> , "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%40yahoogroups.com> 
> > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> ] On Behalf Of bcmcgr
> > Sent: Thursday, February 10, 2011 10:41 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
> > 
> > 
> > 
> > 
> > 
> > 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> 
> > <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%40yahoogroups.com> 
> > > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> 
> > <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> 
> > <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> 
> > > <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%40yahoogroups.com> 
> > > > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> 
> > <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> 
> > > <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
> > > >
> > >
> >
>




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