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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: Fri, 8 Jul 2005 11:36:32 -0500
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There are two things which can change the humidity ratio in a zone:  
infiltration and internal latent loads (assuming you are not using EMPD or MTF 
moisture capacitance modeling).  Turn on report variables to see if there are 
any latent internal gains present (from PEOPLE or equipment) and to see if the 
infiltration flow rate is significant compared to the HVAC system flow rate.

Mike


On 7 Jul 2005, at 16:39, Ali_Ajmi wrote:

> Thanks Mike, I am really appreciate your help even though you are in a Holiday.
> Mike, I changed the VAV damper action to be reverse based on your advice, the
> outputs now more reasonable, however, the humidity ratios are not changing
> between inlet and outlet zones nodes!! Please, could you help me I am really
> running out of time. Excel file for the nodes value is attached.
> 
> Regards
> Ali
> 
> 
> "Michael J. Witte" <mjwitte@xxxxxxxx> wrote:
> 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" 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
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> > > > > 
> > > > > ------- End of forwarded message -------
> > > > > 
> > > > > 
> > > > > 
> > > > > 
> > > > > ---------------------------------
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> > > > 
> > > > 
> > > > 
> > > > ========================================================
> > > > Michael J. Witte, GARD Analytics, Inc.
> > > > EnergyPlus Testing and Support 
> > > > EnergyPlus-Support@xxxxxxxx
> > > > 
> > > > 
> > > > 
> > > > ---------------------------------
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> > 
> > ---------------------------------
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> > [Non-text portions of this message have been removed]
> > 
> > 
> > 
> > The primary EnergyPlus web site is found at:
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> > 
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> 
> 
> ========================================================
> Michael J. Witte, GARD Analytics, Inc.
> EnergyPlus Testing and Support 
> EnergyPlus-Support@xxxxxxxx
> 
> 
> 
> 
> The primary EnergyPlus web site is found at:
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> ---------------------------------
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> [Non-text portions of this message have been removed]
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> 
> 
> The primary EnergyPlus web site is found at:
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> 
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
> 
> Attachments are not allowed -- please post any files to the appropriate folder
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> 



========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx




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Follow-Ups:
- Re: [EnergyPlus_Support] Re: Lots of Warnings
  - From: Ali_Ajmi

References:
- Re: [EnergyPlus_Support] Re: Lots of Warnings
  - From: Michael J. Witte
- Re: [EnergyPlus_Support] Re: Lots of Warnings
  - From: Ali_Ajmi

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