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

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

On Thu, Mar 24, 2011 at 11:09 AM, vieira.jose99 <vieira.jose99@xxxxxxxxx> 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.


--- 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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