Re: [EnergyPlus_Support] Re: AirTerminal:SingleDuct:ParallelPIU LEED ASHRAE

["Jean Marais jeannieboef@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx>]

I agree. I also very vaguely remember the problem that negative values can't be set as tolerances for the nightcycle object and that they are assumed as zero by the program. I'm sure I logged this to the helpdesk, but I don't always express myself well or follow up on my tickets.

The same used to be true for availibilitymanager:outdoorairreset having a "negative sloped line" between the two extreams, but I believe that issue was fixed (and that there was some issue with the fix).

Wasn't there a clever work around for this issue? Hold on...he said throttling range +-2F, i.e. below 2 F above the HeatSetPoint, not below 2 F below the HeatingSetPoint, so +2 F is the correct tolerance. That way you're sure not to get UMLHs right? RIGHT!!?@#%?

Now what about the cooling case?

On 23 Aug 2016 6:17 pm, "fpasserini.tn@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

 

Sheffer has suggested the following document (see pp. 3.97-3.98):

http://www.pnnl.gov/main/publications/external/technical_reports/PNNL-25130.pdf

Consider this statement:

â??With parallel style fan-powered VAV boxes, the constant volume terminal unit fan is only on when the primary airflow is at design minimum and the zone temperature is less than 2°F above the heating setpoint schedule.â??

 

Therefore Iâ??m modeling in the following way.

The PIU boxes are always available. The â??Fan On Flow Fractionâ?? is equal to the â??Minimum Primary Air Flow Fractionâ?? (â??the constant volume terminal unit fan is only on when the primary airflow is at design minimumâ???).

 

AirTerminal:SingleDuct:ParallelPIU:Reheat,

    FloorX09:OXOX1 Parallel PIU,  !- Name

    On,                      !- Availability Schedule Name

    autosize,                !- Maximum Primary Air Flow Rate {m3/s}

    autosize,                !- Maximum Secondary Air Flow Rate {m3/s}

    0.3,                     !- Minimum Primary Air Flow Fraction

    0.3,                     !- Fan On Flow Fraction

    VAV09 Ramificazione di Zona Outlet Node 1,  !- Supply Air Inlet Node Name

    FloorX09:OXOX1 Parallel PIU PIU Secondary