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Re: [EnergyPlus_Support] Re: Lots of Warnings

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Re: Lots of Warnings
From: "Michael J. Witte" <mjwitte@xxxxxxxx>
Date: Tue, 5 Jul 2005 10:03:04 -0500
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The system appears to be operating as specified.  From the Input Output 
Reference for SET POINT MANAGER:MIXED AIR:

"Consequently the mixed air temperature set point must take into account any 
downstream system fan heat if it is to meet a desired system supply air leaving 
temperature. The Mixed Air Set Point Manager accomplishes this by referencing a 
supply air set point set by another set point manager (most likely at the 
primary air system exit node). The supply fan inlet and exit nodes are also 
inputs to the Mixed Air Set Point Manager. From this information the Mixed Air 
Set Point Manager calculates the supply fan air temperature rise, subtracts it 
from the reference set point temperature and uses the result as the mixed air 
node set point temperature."  

VAV SYS 1 OUTLET NODE:System Node Temp[C](Each Call) is 18C when the main 
heating coil is scheduled on.  The temperature leaving the heating coil is 
17.04C and the fan heat raises the supply temperature to 18C.  

For the east and west zone, the reheat coils are running at or near full on, 
and the VAV dampers are at minimum flow, so the resulting supply temperature is 
very high.  This indicates that the VAV damper heating action should be set to 
REVERSE ACTION or these zones need baseboard heat to supplement the VAV system.

Mike


On 1 Jul 2005, at 17:19, Ali_Ajmi wrote:

> I have changed the preheat set preheat design set temperature to 18 C still the
> out put data is look nonsense in the heating season, csv attached. 
>           Inlet temperature is very high 115 C
>           VAV Sys 1 outlet node always less or equal 18C
> Could you help me sort out this problem. 
> Please, could you also elaborate what does you mean in this paragraph
>        'The SET POINT MANAGER:MIXED AIR pushes this setpoint to the heating coil
>        exit 
>         (less the fan heat delta), but the heating coil appears to be unable to
>         meet the load at some times'
> 
> Regards
> Ali
> "Michael J. Witte" <mjwitte@xxxxxxxx> wrote:
> The SET POINT MANAGER:WARMEST object is setting the supply air temperature
> setpoint. It has an upper limit of 18C. So, if no zones require cooling, it will
> max out at 18C.
> 
> The SET POINT MANAGER:MIXED AIR pushes this setpoint to the heating coil exit
> (less the fan heat delta), but the heating coil appears to be unable to meet the
> load at some times. Try setting the "Preheat design set temperature" in the
> SYSTEM SIZING object to 18C.
> 
> Mike
> 
> p.s. I'm gone tomorrow for a 4-day weekend. If you have questions tomorrow,
> please send to the yahoo group or to energyplus-support@xxxxxxxx
> 
> 
> On 30 Jun 2005, at 22:22, Ali_Ajmi wrote:
> 
> > Thanks Mike yes I was confused between the node names. Mike I checked the csv
> > output file every things was reasonable in the cooling design day, however, is
> > not in the heating mode; for example: VAV Sys outlet Node: System Node Temp[C]
> > = 14.46 C VAV Sys outlet Node Setpoint Temp[C] = 18 C Mixed Air temp = 4.89 C
> > 
> > Is the reason heating design setpoint temp. assigned to18 C?
> > 
> > Attached with a CSV of the file you send me for your quick reference.
> > 
> > Regards
> > Ali
> > 
> > "Michael J. Witte" wrote:
> > 
> > My csv output file does not look like that. Are you sure you are not confusing
> > several very similar node names. The only way that a given
> > keyname+reportvariable combination can appear more than once in a csv file is
> > if one is if the same thing is reported with and without schedule or at a
> > different reporting frequency.
> > 
> > Mike
> > 
> > 
> > On 29 Jun 2005, at 17:24, Ali_Ajmi wrote:
> > 
> > > Thanks Mike for sending me the file. Mike I have looked it and generate a
> > > run, the out put seems reasonable, however, I have some inexplicable out
> > > puts data. These are as follows: 1) Zone North in Node: System node Temp [C]
> > > has two values in two different columns in the out puts; 15 C and 35 C. 2)
> > > Zone North Node: System node setpoint Temp[C] has two values, -999 and 25 C.
> > > 
> > > Please could advice me what may the reasons.
> > > 
> > > Regards
> > > Ali
> > > 
> > > "Michael J. Witte" wrote:
> > > I passed it along to another team member but I haven't heard back. My file
> > > without return fan shows loads. See attached.
> > > 
> > > Mike
> > > 
> > > 
> > > On 23 Jun 2005, at 16:55, Ali_Ajmi wrote:
> > > 
> > > > "Michael J. Witte" wrote:
> > > > Not sure if there's a problem with the way the return fan is described or
> > > > if it's a programming problem.
> > > > 
> > > > Mike I deleted the return fan, every things went smooth. However, the
> > > > sensible heating/cooling of the zones were Zeros. Have you checked if the
> > > > progarm, E+, has problem with return fan? 
> > > > 
> > > > Thanks
> > > > Ali
> > > > 
> > > > 
> > > > Tried one more thing - deleted the return fan and the errors went away.
> > > > Not sure if there's a problem with the way the return fan is described or
> > > > if it's a programming problem.
> > > > 
> > > > Mike
> > > > 
> > > > 
> > > > ------- Forwarded message follows -------
> > > > From: Michael J. Witte 
> > > > To: ajmi70kw@xxxxxxxxxxx
> > > > Subject: Re: Lots of Warnings
> > > > Date sent: Thu, 9 Jun 2005 16:43:47 -0500
> > > > 
> > > > For some reason, the air loop components are fighting over whether there
> > > > is flow in the system at certain times, which is causing some iterations
> > > > to evalute the coil at a very low airflow rate which causes the errors. I
> > > > will have to ask someone else to look at this to figure out if it's an
> > > > input problem or not. Ultimately, I think the final results are OK, just
> > > > some of the early iterations are confused.
> > > > 
> > > > Mike
> > > > 
> > > > 
> > > > On 7 Jun 2005, at 10:56, Ali_Ajmi wrote:
> > > > 
> > > > > Dear Mike,
> > > > > I am still struggling to sort out my IDF file
> > > > > (VAVEnvlopBuild_fivZone1.idf). I have implemented your advices where I
> > > > > changed the set point manger to Warmest, however, when I tried to use
> > > > > the Coldest set point manger the file is crashed. Also I have changed
> > > > > the time step in average window to be 1.4. Then I imitate the
> > > > > 5ZoneAutoDXVAV.idf in the example files folder to be sure that both IDFs
> > > > > are almost similar. However, still i have lots of warnings, about
> > > > > 20,000. Please could have a look to the file (attached). Mike could you
> > > > > kindly treat this problem as urgent because I am ruining out of time to
> > > > > implement my PhD research experiments.
> > > > > 
> > > > > File will be uploaded at the submitals_problem folder. I am using now
> > > > > E+1.2.2. Regards Ali 
> > > > > 
> > > > > 
> > > > > 
> > > > > 
> > > > > ---------------------------------
> > > > > Yahoo! Messenger NEW - crystal clear PC to PCcalling worldwide with
> > > > > voicemail
> > > > 
> > > > 
> > > > ------- End of forwarded message -------
> > > > 
> > > > 
> > > > 
> > > > 
> > > > ---------------------------------
> > > > Yahoo! Messenger NEW - crystal clear PC to PCcalling worldwide with
> > > > voicemail
> > > 
> > > 
> > > 
> > > ========================================================
> > > Michael J. Witte, GARD Analytics, Inc.
> > > EnergyPlus Testing and Support 
> > > EnergyPlus-Support@xxxxxxxx
> > > 
> > > 
> > > 
> > > ---------------------------------
> > > Yahoo! Messenger NEW - crystal clear PC to PCcalling worldwide with
> > > voicemail
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > ---------------------------------
> > Yahoo! Messenger NEW - crystal clear PC to PCcalling worldwide with voicemail
> 
> 
> 
> 
> 
> 
> 
> 
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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx




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- [EnergyPlus_Support] Re: Lots of Warnings
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