[EnergyPlus_Support] Re: RE:AHU1 Gallery Store PostZTR Hum.idf

["civilnug" <civilnug@xxxxxxxxx>]

Thanks a million Mike, that's been driving me a bit mad for a while 
now. 

Thank you,
John.



--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Michael J. Witte" 
<mjwitte@g...> wrote:
> If I understand correctly, this system is supposed to supply a 
fixed flow rate 
> at a specified supply temperature rather than adjust supply 
temperature to 
> match the zone load.
> 
> Assuming that is correct, the problem is that the various setpoint 
managers are 
> fighting with each other because the cooling coil and heating coil 
are using 
> the same control node.  SET POINT MANAGER:SCHEDULED "AHU1 Supply 
Air Temp 
> Manager" places a setpoint on "AHU1 Fan Outlet Node".  Then SET 
POINT 
> MANAGER:SINGLE ZONE MAX HUM "zBaseGalleryStore Max Hum Manager" 
places a 
> humidity ratio setpoint on the same node.  What is not well-
documented is that 
> the CONTROLLER:SIMPLE resets the control node setpoint if the max 
humidity 
> conditions requires more cooling.  To see the impact of this, add 
report 
> variable "System Node Setpoint Temp" for AHU1 FAN OUTLET NODE.
> 
> Because of this, the heating coil controller needs to use a 
different control 
> node.  An easy solution would be to add "AHU1 HC Outlet Node" to 
the NODE LIST 
> for "Supply Air Temp Nodes".  And change the AHU1 Heating Coil 
Controller 
> control node to be "AHU1 HC Outlet Node".  This should solve the 
problem.
> 
> Mike
> 
> 
> On 12 Sep 2005, at 14:58, civilnug wrote:
> 
> > Hi All,
> > 
> > I've put the above idf in the Problem_Submittals file. In it I 
have, 
> > in order, a mixing box, cooling coil, heating coil and 
humidifier on 
> > the air loop. This is fed into an area by a direct air system 
and has 
> > to have tightly controlled relative humidity levels (50% +/- 
5%). The 
> > system is operating perfectly in winter but my problem is 
occuring 
> > during the summer months when attempting to get control of the 
rh. 
> > 
> > The cooling coil kicks in to drag down the temperature below the 
> > supply air temperature so as to get the humidity ratio to the 
right 
> > level, my problem is that the heating coil won't kick in to 
bring the 
> > temperature back up to the specified supply air temperature.
> > 
> > Any help would be greatly appreciated.
> > 
> > Regards,
> > John McCarthy.
> > 
> > 
> > 
> > 
> > 
> > 
> > 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 not allowed -- please post any files to the 
appropriate folder
> > in the Files area of the Support Web Site.
> > 
> > Yahoo! Groups Links
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> 
> 
> 
> ========================================================
> Michael J. Witte, GARD Analytics, Inc.
> EnergyPlus Testing and Support      
> EnergyPlus-Support@g...





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