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[EnergyPlus_Support] Re: AHU not turning on
That's right. This "Air Wall Material" is used to calculate the U-value (which is a combination of conduction and surface convection properties) to describe the heat transfer across the wall. Air passing over a wall needs to be described seperately using airnetworks. You need to set up a airflow network (calculated natural ventilation):see page 851 InputOutputReference
AirflowNetwork:MultiZone:Surface:Crack, !- Crack used to connect zones to make AIRFLOWNETWORK:MULTIZONE network valid
DefaultCrack, !- Crack Name
0.00000000001, !- Flow coeff (kg/s @ 1Pa)
0.66, !- Flow exponent
Reference Crack Conditions; !- Reference crack conditions
ScheduleTypeLimits, Any Number; ! Not limited
ScheduleTypeLimits, Fraction, 0.0, 1.0, CONTINUOUS;
ScheduleTypeLimits, Temperature, -60, 200, CONTINUOUS;
ScheduleTypeLimits, Control Type, 0, 4, DISCRETE;
ScheduleTypeLimits, On/Off, 0, 1, DISCRETE;
AirflowNetwork:SimulationControl,
VENT, !- AirflowNetwork Simulation Name
MultizoneWithoutDistribution, !- AirflowNetwork Control
Input, !- Wind Pressure Coefficient Type
Cp Data, !- AirflowNetwork Wind Pressure Coefficient Array Name
OpeningHeight, !- Height Selection for Local Wind Speed Calculation
LowRise, !- Building Type
500, !- Maximum number of iterations
ZeroNodePressures, !- Initialization flag
.0001, !- Relative airflow convergence tolerance
.000001, !- Absolute airflow convergence tolerance
-0.5, !- Convergence acceleration limit
0.000000000000000E+000, !- Azimuth Angle of Long Axis of Building
1.00000000000000; !- Ratio of Building Width Along Short Axis to Width Along Long Axis
...and then you need at least 2 zones
AirflowNetwork:MultiZone:Zone,
118129, !- Name of Associated Thermal Zone
Temperature, !- Ventilation Control Mode
20001, !- Vent Temperature Schedule
, !- Limit on multiplier for modulating venting open factor
, !- Lower value on inside/outside temperature difference for modulating the venting open factor
, !- Upper value on inside/outside temperature difference for modulating the venting open factor
, !- Lower value on inside/outside enthalpy difference for modulating the venting open factor
, !- Upper value on inside/outside enthalpy difference for modulating the venting open factor
12345; !- Venting Availability Schedule Name
...a crack is just a air travel path and can describe air flow over doors or windows or large open areas (Bi-directional flow through large openings are very badly approximated...See discussion below under
AirflowNetwork:MultiZone:Component:DetailedOpening,
AirflowNetwork:Multizone:Component:HorizontalOpening, and
AirflowNetwork:Multizone:Component:SimpleOpening.
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "grandocu" <jgrando@...> wrote:
>
> The air wall objects are just buildingsurface:detailed objects. do they let air out of the zone if they don't completely close it? I thought I had to specify those interactions elsewhere in the .idf.
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "grandocu" <jgrando@> wrote:
> >
> > This .idf is just one air handler that makes up the entire building. However, to reduce run time I separated the system components to just deal with this airloop. Even if all the walls are included in the original .idf I get the same problems.
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "jeannieboef" <jeannieboef@> wrote:
> > >
> > >
> > > I saw in the eso that the fan is drawing electricity at the schuduled time, so I assumed the fan was turning on. I saw the system and airloop was turning on, but the air flow remained zero, which lead me to believe that the fan is working and making pressure, but that as the air in the zone has nowhere to go, that the back pressure simply builds up and no flow insues. I'm assuming that these are supply fans. I did not check the fan schedule. your schedules themselves looked good.
> > >
> > > I'll have another look on Monday.
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "grandocu" <jgrando@> wrote:
> > > >
> > > > Actually the fan never turns on if you look at the .eso file. It is zero for the whole day. I don't get how this particular airloop is refusing to turn on.
> > > >
> > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "jeannieboef" <jeannieboef@> wrote:
> > > > >
> > > > > 1)It looks like you pump air into the room but nothing gets out...
> > > > > ** Warning ** In AirLoopHVAC AHU-B-5 there is unbalanced exhaust air flow.
> > > > > ** ~~~ ** During Warmup, Environment=ANNSIM, at Simulation time=07/20 06:00 - 06:10
> > > > > ** ~~~ ** Unless there is balancing infiltration / ventilation air flow, this will result in
> > > > > ** ~~~ ** load due to induced outdoor air being neglected in the simulation.
> > > > >
> > > > > I would check the node connections. Nothing obvious.
> > > > >
> > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "grandocu" <jgrando@> wrote:
> > > > > >
> > > > > >
> > > > > > Okay, just posted it to the user exchange as building.zip with subtitle "AHU Problem". Thank you for your help.
> > > > > >
> > > > > >
> > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "jeannieboef" <jeannieboef@> wrote:
> > > > > > >
> > > > > > > I don't have access here it appears...could you upload it to Files/User Exchange?
> > > > > > >
> > > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "grandocu" <jgrando@> wrote:
> > > > > > > >
> > > > > > > > It's labeled as building.zip with the sub-title "AHU Problem" Thanks. The availability is ON for the system.
> > > > > > > >
> > > > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "jeannieboef" <jeannieboef@> wrote:
> > > > > > > > >
> > > > > > > > > Check both the system availibility and the fan availibility is ON. I don't see your file. Is it in Files/Problem Submittals?
> > > > > > > > >
> > > > > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "grandocu" <jgrando@> wrote:
> > > > > > > > > >
> > > > > > > > > > Hello,
> > > > > > > > > >
> > > > > > > > > > I have an air handling unit that is not turning on even though it is scheduled on and has a cooling load not met. I have no idea why it's refusing to run. I have attached the .idf please let me know if anyone has any idea why this is happening.
> > > > > > > > > >
> > > > > > > > > > I posted the problem in 'files' under "AHU Problem".
> > > > > > > > > >
> > > > > > > > > > Thank you.
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>
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