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[EnergyPlus_Support] Re: AirTerminal:SingleDuct:VAV:NoReheat

Thank-you for your help. I have been trying all day now the AirTerminal:SingleDuct:Uncontrolled but still cannot set up it so room temperatures ar at minimum 20ºC maximum 25ºC. I have tried a few options on the setpoint manager and cannot get to the minimum temperture in winter.
Lets say a have a AHU, no zone reheat. The AHU must handel the loads, so room mean air temperature is 20ºC to 25ºC year-round. 

I have tried using a controller for the heat and cool water coils, but have to define a "zone inlet node" temperature setpoint(or a splitter inlet node temperature setpoint), this is where I have problems, I want that node temperature to get automatically set depending on room temperature and its thermostat. But when using a controller for these coils i must set setpoint temperatures for them.

I have tried the system without the cool and heat water coil controllers, and run the simulation, but still cannot get 20/25ºC.

The system is mostly on "autosize" so there are no limitations to coil and fan capacities.

I have no internal gains setup. I am studing these option for my thesis in with i will have to simulate an AHU. Please can someone point me in the right direction? I am not seeing what is missing.


Thank-you all for helping


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, x z <xs.zhang.2010@...> wrote:
>
> Hi Vieira,
> 
> I had the same issues when I was debuging my model with
> AirTerminal:Singleduct:VAV:NoReheat or AirTerminal:SingleDuct:Uncontrolled.
> (I used AirTerminal:SingleDuct:Uncontrolled)
> 
> There is tricky question whether you have one air-handler serving one zone
> or multiple zones. If multiple zones, you may risk that your AHU's supply
> air condition satisfy one zone's heat load but may not meet other zones'.
> You can try some SetpointManger for your supply air condition. It really
> depends on your zones' heat load profile
> 
> If only one zone per AHU. Then you should be able to get your zone
> temperature under control by using SetPointManager:WrmestTemperatureFlow or
> some others for your supply air condition. Basically, you give the lowest
> (cooling) and highest (heating) supply air condition. Then the system will
> determine the SAT based on your load condition
> 
> Another thing to check is your thermostat. Sometime your temperature is
> seating between the deadband. Properly setup the deadband or simply use
> control type 1 or 2 if you heating/cooling need is simple may also help
> 
> XS
> 
> On Thu, Mar 24, 2011 at 11:09 AM, vieira.jose99 <vieira.jose99@...>wrote:
> 
> >
> >
> > I have verified that i cannot create a AirTerminal:Singleduct:VAV:NoReheat
> > to get zone temperatures in between 20/25 ºC. I have to define a controller
> > to the heating and cooling coils (both water) of the air handeling unit then
> > that makes me define setpoint air temperatures of the air entering the zone.
> >
> > Even if i delete the heat coil controller, the zone temperature in winter
> > does not reach 20ºC.
> >
> > Basically I want to simulate an Air Handeling Unit with pre-heat, cooling
> > and heating coil (all water), mixing box and a variable fan. No terminal
> > reheating.
> >
> > What option must i choose?
> > Air:Terminal:SingleDuct:Uncontrolled?? if i choose this i think i cannot
> > define de airBranch;
> > Or should i look into NaturalVentilationAndDuctLeakage for the system? but
> > this does not allow the choise of a variable fan.
> >
> > Thank-you
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad <RRaustad@>
> > wrote:
> > >
> > > Sounds like you need to include a heating coil in the air loop when
> > > using AirTerminal:Singleduct:VAV:NoReheat. I you already have one then
> > > you are not controlling it correctly or the zone loads are so diverse
> > > that some will wind up below 20C. This can sometimes be corrected by
> > > balancing the air loop flow rates to each zone (i.e., giving more flow
> > > to colder zones and less flow to warmer zones).
> > >
> > > The supply air reset schedule is used to minimize heating energy in
> > > winter. If you kept the same cold supply air temperature all year
> > > around, the heating coils would have to work harder in the winter.
> > >
> > > On 3/24/2011 5:47 AM, vieira.jose99 wrote:
> > > >
> > > > AirTerminal:SingleDuct:VAV:NoReheat
> > > >
> > > > I have set up everything, but I want the mean air temperature to be in
> > > > between 20 and 25ºC. But this does not happen. I have the thermostats
> > > > configured to be 20/25ºC.
> > > > The mean air temperature just stays a few degrees above the outside
> > > > air temperature.
> > > > I have the coils, boiler and chiller on autosize.
> > > >
> > > > When I configure the same setup to AirTerminal:SingleDuct:VAV:Reheat
> > > > with reheat coils on autosize, I get it to be in between 20 and 25ºC.
> > > >
> > > > Any advice?
> > > >
> > > > Also....can someone explain what is the "Seasonal Reset Supply Air
> > > > Temp Sch" for? I have read the inputoutput, but still cannot
> > > > understand the basics of this schedule.
> > > >
> > > > thank-you
> > > >
> > > >
> > >
> > > --
> > > Richard A. Raustad
> > > Senior Research Engineer
> > > Florida Solar Energy Center
> > > University of Central Florida
> > > 1679 Clearlake Road
> > > Cocoa, FL 32922-5703
> > > Phone: (321) 638-1454
> > > Fax: (321) 638-1439 or 1010
> > > Visit our web site at: http://www.fsec.ucf.edu
> > >
> > > UCF - From Promise to Prominence: Celebrating 40 Years
> > >
> >
> > 
> >
>




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