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[EnergyPlus_Support] Re: Problem with removing reheat coils in VAV
Hi Jean,
I've tried to send the file in attachment but I think it failed (I'm still learning how to work with the Yahoo! Groups...).
I putted it in the "Files"->"_Problem_Submittals"->" EDIT_OF_HVACTemplate-5ZonePackagedVAV.idf ".
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!
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais" <jeannieboef@...> wrote:
>
> Post some code snipbits, like the setpoint manager.
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "n_junk" <n_junk@> wrote:
> >
> > Many thanks for your help, but I still have the same problem.
> >
> > I changed the scheduled setpointmanager for the singlezone:heating, but it made no difference.
> >
> > What I did was this:
> > - opened the example file "HVACTemplate-5ZonePackagedVAV.idf" with the Chicago weather file;
> > - changed the thermostat so that the interior temperature should be between 20-25ºC (with the reheat coils active the temperature stays in this limit, so the problem is not from here);
> > - removed the reheat coils and the cooling coil;
> > - removed all the lights and electric equipment and most of the people (just to eliminate the influence of internal heating loads);
> > - changed the heating design temperature from 10ºC to 40ºC;
> > - deleted the SetpointManager:Scheduled for Heating and created the SetpointManager:SingleZone:Heating, using the Space3-1 as the control zone name (it's the zone with more heating demands).
> >
> > And then the temperatures of Space3-1 (and others) are not hot enough. What else can be wrong? Could the problem be in the setpointmanager: MixedAir ?
> >
> > Thanks in advance!
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad <RRaustad@> wrote:
> > >
> > > If you remove the terminal unit heating coils, you can no longer control
> > > the air loop heating coil at a constant supply air temperature (i.e.,
> > > using a scheduled temperature set point). Verify how the main heating
> > > coil is controlled (i'm guessing scheduled) and use a different type of
> > > set point manager to control it (e.g., SetpointManager:SingleZone:Heating).
> > >
> > > On 7/11/2011 7:01 PM, n_junk wrote:
> > > >
> > > >
> > > > Hi! You are refering to "Central Heating Design Supply Air
> > > > Temperature", right? I forgot to tell that I already had changed it to
> > > > 20, 30, 40, 50 and even 70ºC and none of them hadn't change at all the
> > > > interior temperature. If I use a high temperature and put again the
> > > > reheat coils, the rooms sometimes even overheat, but without them the
> > > > temperatures continues under 20ºC.
> > > >
> > > > This is really odd, I don't know what is happening.
> > > >
> > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > > <mailto:EnergyPlus_Support%40yahoogroups.com>, Vinay Devanathan
> > > > <vinay.devanathan@> wrote:
> > > > >
> > > > > The main heating coils setpoint temperature will be set such that it
> > > > only
> > > > > heats air to a certain temp, (say around 15 - 16 C), so that the reheat
> > > > > coils can be sized for proper capacity to meet the load. When you
> > > > remove the
> > > > > reheat coils, your supply air will obviously be under-heated as the main
> > > > > heating coil is not sized for that high capacity and will end up
> > > > providing
> > > > > supply air at the setpoint temperature. You can look at what the heating
> > > > > coils design leaving air temperature by viewing the expidf file under
> > > > > Sizing:System object.
> > > > >
> > > > > On Mon, Jul 11, 2011 at 1:02 PM, n_junk@ <
> > > > > n_junk@> wrote:
> > > > >
> > > > > > **
> > > > > >
> > > > > >
> > > > > > Hi!
> > > > > >
> > > > > > I'm trying to simulate an existing HVAC system which is similar to
> > > > a VAV,
> > > > > > only with heating, without cooling coil or reheat coils. I'm using
> > > > the HVAC
> > > > > > Template VAV Packaged.
> > > > > > The rooms' temperatures stay above 20ºC, like I configured in the
> > > > > > Thermostat, until I remove the reheat coils. When I do that the
> > > > temperature
> > > > > > drops under 20ºC and only reaches it if there are internal loads.
> > > > > >
> > > > > > I have almost everything in autosize, except the maximum flow of
> > > > the input
> > > > > > air (but autosize never reaches it, so I think the problem is not from
> > > > > > there).
> > > > > >
> > > > > > To see my problem just open this example file that comes with
> > > > EnergyPlus:
> > > > > > HVACTemplate-5ZonePackagedVAV.idf. Then run a simulation and
> > > > consult the
> > > > > > evolution of Zone Air Temperature for any of the conditioned zones
> > > > and see
> > > > > > that it stays inside the temperatures of the Thermostat. After
> > > > that go to
> > > > > > the file, remove the reheat coils of every zone (and deactivate
> > > > the system
> > > > > > cooling coil), run the simulation again and compare the
> > > > temperatures. You'll
> > > > > > see that now the temperatures stay under the Thermostat limit and
> > > > only reach
> > > > > > it when the internal loads harm the room enough.
> > > > > >
> > > > > > I'm looking in the expidf file for days and I still don't know what is
> > > > > > wrong with it. Since I really have to remove the reheat coils,
> > > > what can I do
> > > > > > to correct this problem?
> > > > > >
> > > > > > Thanks in advance!
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > >
> > > --
> > > 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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