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

["Jim Dirkes jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx>]

Francesco,

Is there any reason you cannot increase the zone sizing factor? or the reheat coil capacity? 

As usual, I recommend creating some output:variables for a problem zone so that you can carefully analyze where the problem is occurring. These variables should include:

• primary air flow and temp
• secondary air flow and temp
• reheat coil flow and temp
• zone temp and setpoint

These will enable you to see whether you have airflow as expected, proper coil capacity, etc.

On Fri, Jul 22, 2016 at 1:34 PM, fpasserini.tn@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

 

I'm reading this old discussion again because I'm trying to respect G3.1.3.14, in particular: "Fans in parallel VAV fan-powered boxes shall be sized for 50% of the peak design flow rate". 

I'm using this useful James's suggestion:

I do not know of a way to automatically size the PFP fan for 50% of the maximum primary flow rate, so I run the program once using â??autosizeâ?? for primary flow rate, then check to see the autosized value, then enter 50% of that into the fan â??Maximum flow rateâ??.

I used this suggestion also in the past, but now I'm facing a problem. After that I have imposed the "Maximum Secondary Air Flow Rate" of the object AirTerminal:SingleDuct:ParallelPIU:Reheat equal to 50% of the "Maximum Primary Air Flow Rate", the heating setpoint not met hours have increased a lot. It seems reasonable, because in centralized VAV systems with PFP boxes the heating demand is met by the secondary flow rate.

What do you think? Any suggestion, please?

Best Regards

Francesco

 

--

James V Dirkes II, PE, BEMP, LEED AP
CEO/President
The Building Performance Team Inc.
1631 Acacia Dr, GR, Mi 49504

Direct: 616.450.8653
jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx

Website l  LinkedIn | May 2016 ASHRAE Journal article on energy modeling

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Posted by: Jim Dirkes <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx>

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