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[EnergyPlus_Support] Re: Problem with removing reheat coils in VAV

Hi Dr. Li,

Many thanks for your assistance! 
I'm trying to analyze what you've said and see what I can change in my file. 

Since it's my first simulation in energyplus, I'm still trying to learn the basics.
One thing that it's very odd to me and I can't understand at all it's the behavior of the heating coils of the system. I really don't know what is controlling them, in the program. Everytime I deactivate (not remove, just shut them off) the reheat coils in the zones, the heating coil of the main system seems to just turn off, even if I put setpoints in the heating coil outlet temperature or rise the design temperature. It's like the program quits to care about controlling the setpoint temperatures I inserted everytime I shut off the reheat coils.

I was expecting something far more easy and simple, that when I removed the reheat coils the program would 'think': «ok, since I can't rely anymore on the reheat coils, I need to heat more the air in the system's heating coil, so I will rise the heating coil's capacity». If I'm just shutting off the reheat coils, and not removing anything, and even rising the "heating coil design setpoint" in the HVACTemplate:System:PackagedVAV, what is going so wrong that shuts off or undersizes the heating coil's capacity, makes the setpoint temperatures not being met and doesn't heat the zones as expected?

Please note again that I'm still learning the basics of EnergyPlus and I'm using the HVACTemplates as a starting point, and then editing the expidf file, because it would be impossible to me to design all the air, system and plant loops, with my current knowledge, in time to deliver my thesis.

Once again, thanks in advance!



--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, YuanLu Li <yli006@...> wrote:
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> Hi, Lixeira I think you are trying to replace the usual air loop with one master zone thermostat control with one which uses the set point manager to control the air  loop temperature and variable damper at the zone without reheat coil.  In this way all thermostat are available in each zone. Because you are using setpoint manager for the air loop, the temperature should not be a range, but one temperature slightly below the wanted zone temperature.  This difference is normally compensated by reheat. The heating should also be slightly lower.  The type 4 dead band should also be maintained at the zone, with modified schedules. When the OA is cool in Summer, your system is turning on the heater to keep the temperature at the zone thermostat setting.
> There is no severe error. Just need some tuning on the available schedules and set point values or managers.   AirTerminal:SingleDuct:VAV:NoReheat,  should not be running at constant mode. I do not know how to change this yet.  What I did of my own project  was to use the one with reheat and disable the coil, not removing it, so that the damper will still have control of the air flow. Because the zone demand loads are not the same and dampers are not controlled, therefore the temperatures are all different.  Dr. Li   
>  To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> From: n_junk@...
> Date: Sat, 16 Jul 2011 09:39:20 -0700
> Subject: [EnergyPlus_Support] Re: Problem with removing reheat coils in VAV
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>       Hi Jean,
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> I'm sending the file that I'm testing as an e-mail attachment. I hope that the attachment will be send and received without errors.
> Note that the "plenum" temperatures are not controlled, but all the "spaces" temperatures should be controlled (always above 20ºC).
> Could the problem be in the VAV terminal damper position?
> 
> Thanks in advance!
>




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