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Re: [EnergyPlus_Support] Fan will not produce airflow



Thanks, Jean.
The building is only 3,000 sq. meters, so it certainly doesn't need such a large airflow - that might be a clue.
I have looked at the availability manager (NightCycle) and it appears proper.  Also, there is zero fan power for an entire year, so the one minute operation does not sound valid.  Pressure rise is non-zero also.  (If it were zero, power would be zero, but not flow)
Still looking....

On Sun, Nov 2, 2014 at 6:31 AM, 'jeannieboef@xxxxxxxxx' jeannieboef@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
 

Do a text search to list all "Managers" to see if there is not perhaps a higher priority Manager (like nightvent) forcing the system off. Also, you often have an EMS in your programs which force your fans off at low ODAtemps.

11m3/s = 39600 m3/h...that is a huge AHU. Due to height restrictions both on the roof or in the cellar, AHUs bigger than 25000 m3/h are uncommen and impracticle. The biggest I've seen for space conditioning was 50000. So it may be that your system's minimum flowrate is so large that just by switching it on for only a moment at say 40%min airflow would overcool your space (depending on how your pump/coil control/operation...variabe/intermittant...primary/secondary with heatexchanger or coomonpipe or 3-way valve, etc.)?  

Mit freundlichen Grü�en- Sent from my iPhone (excuse the brevity)

i. A.
Jean Marais
b.i.g. bechtold

On 01.11.2014, at 21:08, "Jim Dirkes jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

 

Dear Forum,
I have defined a simple system with a VAV fan serving several zones.  Throughout the year, the fan never produces flow, despite:
  • The fan schedule is ON as expected for many hours
  • Various zones have a cooling demand and unmet cooling loads
  • The discharge air setpoint for the air loop is lower than the actual temperature
  • The fan is autosized at about 11 m3/s, i.e. it's not zero.
I have not been able to determine how the fan can be scheduled "on" and produce no flow...
Thanks in advance for your assistance.


--

 

James V Dirkes II, PE, BEMP, LEED AP
The Building Performance Team
1631 Acacia Drive, Grand Rapids, MI 49504
(M) 616 450 8653

The more one does what is good, the freer one becomes. There is no true freedom except in the service of what is good and just.

<Grace 141101 - reduced elect.idf>
<Grace 141101 - reduced elect.rvi>




--

 

James V Dirkes II, PE, BEMP, LEED AP
The Building Performance Team
1631 Acacia Drive, Grand Rapids, MI 49504
(M) 616 450 8653

The more one does what is good, the freer one becomes. There is no true freedom except in the service of what is good and just.



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Posted by: Jim Dirkes <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx>


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