Re: [EnergyPlus_Support] Terminal Reheat System controls

["Michael J. Witte" <mjwitte@xxxxxxxx>]

Sorry to respond rather late here.  

Thanks for the clarifications.  I have made a note to add text to the reheat 
terminal unit descriptions in the Input Output Reference.

Just to clarify, reheat coils in EnergyPlus are *always* controlled to maintain 
the heating setpoint, not just in setback/setup mode.

Mike


On 17 Apr 2008 at 15:53, JV Dirkes II wrote:

> Dear EPlus Forum,
> 
> For your general information and (hopefully) benefit:
> E+ essentially ignores the Cooling setpoint (SP) for reheat systems
> when  in the setback / setup mode.  Instead, it uses the Heating SP. 
> The logic behind this is that reheat systems use MORE energy to
> maintain a higher SP, so no one will really want to control their
> reheat system to a higher unoccupied SP.
> In order, however, to get realistic results, I recommend that you
> consider comfort and practical issues when establishing the Heating SP
> schedule.  For example, if a normal SP scheme is to use 20C for the
> occupied Heating SP, and 25C for Cooling SP, you are likely to have
> unhappy occupants in the Summer when they find that the room
> temperature is 20C on a mild (non-design) day!  Most people do not
> like to walk in from 35C to a 20C room -- too much change.
> For this reason, I have revised my Heating SP schedule to use a higher
> SP (e.g., 22C) in the Summer and lower (e.g., 20C) in the Winter.  As
> a practical matter, check to see whether the control system actually
> uses setpoints in the same way as E+; then make E+ mimic the real system!
> 
> Development Team, I am hoping that this information can be added to
> the User Reference.
> 
> Finally, for those of you running Energy Analysis for LEED
> certification, the Set Point Manager: NightCycle "on/off tolerance"
> setting can add a LOT of hours to the "unmet loads" report if you set
> it too high.  Apparently E+ considers a load "unmet" if the zone temp
> is more than 0.2C apart from the SP.  Therefore, making the "on/off
> tolerance" higher than .2C runs the risk of dramatically increasing
> the number of hours E+ considers for an "unmet load".
> 
> Hope this was helpful!
> 
> 
> 
> ------------------------------------
> 
> 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.
> 
> EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
> Yahoo! Groups Links
> 
> 
> 



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

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.

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:
    mailto:EnergyPlus_Support-digest@xxxxxxxxxxxxxxx 
    mailto: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/