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[EnergyPlus_Support] Re: Full Fresh Air system with heat recovery and NO heating or cooling coils in loop



Hi Fred,

Thanks for that. I am using a heat exchanger air to air generic 
which looks like the following...

HEAT EXCHANGER:AIR TO AIR:GENERIC,
    AHU1 Enthalpy Wheel,     !- Heat exchanger name
    FanAndCoilAvailSched,    !- Availability schedule name
    0.24,                    !- Nominal supply air flow rate {m3/s}
    0.76,                    !- Sensible effectiveness at 100% 
airflow heating condition {dimensionless}
    0.68,                    !- Latent effectiveness at 100% airflow 
heating condition {dimensionless}
    0.81,                    !- Sensible effectiveness at 75% 
airflow heating condition {dimensionless}
    0.73,                    !- Latent effectiveness at 75% airflow 
heating condition {dimensionless}
    0.76,                    !- Sensible effectiveness at 100% 
airflow cooling condition {dimensionless}
    0.68,                    !- Latent effectiveness at 100% airflow 
cooling condition {dimensionless}
    0.81,                    !- Sensible effectiveness at 75% 
airflow cooling condition {dimensionless}
    0.73,                    !- Latent effectiveness at 75% airflow 
cooling condition {dimensionless}
    AHU1 OA Inlet Node,      !- Supply air inlet node name
    AHU1 MB OA Inlet Node,   !- Supply air outlet node name
    AHU1 MB Relief Air  Outlet Node,  !- Exhaust air inlet node name
    AHU1 Exhaust Node,       !- Exhaust air outlet node name
    200.0,                   !- Nominal electric power {W}
    Yes,                      !- Supply air outlet temperature 
control
    Rotary,                  !- Heat exchanger type
    None;                    !- Frost control type

As you can see, I set the 'Supply air outlet temperature control' to 
YES in order to moderate the intensity of heat exchange between the 
two streams. However, I would prefer to give priority to zone 
temperature. Is there any way to doing this?

The reason I want to do this is because on the rare occasions in 
Ireland when outdoor temp is above 21oC, then the inlet stream temps 
will be above my heat recovery outlet temp setpoint. Unfortunately, 
this seems to make the heat recovery unit think it should engage in 
full heat recover which pushes outlet temperatures well over 50oC 

Any help would be greatly appreciated or am I missing something here?

Kind regards

-Elmer


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, fred buhl <wfbuhl@l...> 
wrote:
>
> Not sure what your system looks like. Your Controller:Outside Air 
object 
> looks
> fine. What you should note is that all all central air systems in 
> EnergyPlus are loops.
> That is, they are configured for recirculated air even if there is 
none. 
> The air loop
> does not need heating or cooling coil or any kind of controller. 
All it nees
> is at least 1 component. The Controller:Outside Air
> can not be assigned to the Air Primary Loop in the controller 
list. It 
> should be part
> of the Outside Air System, named in its controller list.
> 
> Fred
> 
> Elmer Morrissey wrote:
> 
> >Hi Fred,
> >
> >I've set my OA controller to the following..
> >
> >CONTROLLER:OUTSIDE AIR,
> >    AHU1 OA Controller,      !- Name
> >    NO ECONOMIZER,           !- EconomizerChoice
> >    NO RETURN AIR TEMP LIMIT,!- ReturnAirTempLimit
> >    NO RETURN AIR ENTHALPY LIMIT,  !- ReturnAirEnthalpyLimit
> >    NO LOCKOUT,              !- Lockout
> >    PROPORTIONAL MINIMUM,    !- MinimumLimit
> >    AHU1 Supply Fan Inlet Node,  !- Control_Node
> >    AHU1 OA Inlet Node,      !- Actuated_Node
> >    0.21,                     !- minimum outside air flow rate 
{m3/s}
> >    0.21,                    !- maximum outside air flow rate 
{m3/s}
> >    19,                      !- temperature limit {C}
> >    4,                       !- temperature lower limit {C}
> >    0,                       !- enthalpy limit {J/kg}
> >    AHU1 MB Relief Air  Outlet Node,  !- Relief_Air_Outlet_Node
> >    AHU1 Extract Fan Outlet Node;  !- Return_Air_Node
> >
> >Do I need an econmizer for what I am proposing to do? 
> >
> >What would be the correct course of action in order to remove my 
> >error for the fatal error described below that seems to insist on 
a 
> >Controller:Simple even though I do not have a heating coil or a 
> >cooling coil? Do I need to insert a fake cooling coil with dummy 
> >controls?
> >
> >Kind regards
> >
> >-Elmer
> >
> >--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, fred buhl 
<wfbuhl@l...> 
> >wrote:
> >  
> >
> >>You'll need to pretend that the system is a recirc system with 
> >>    
> >>
> >outside 
> >  
> >
> >>air - ie a normal
> >>VAV system. You will need to set the minimum OA to the total 
flow 
> >>    
> >>
> >rate. 
> >  
> >
> >>The heat recovery
> >>unit will be in the OA system. Probably need to set MinimumLimit 
> >>    
> >>
> >to 
> >  
> >
> >>Proportional Minimum
> >>in the controller:outside air.
> >>
> >>Fred Buhl
> >>
> >>Elmer Morrissey wrote:
> >>
> >>    
> >>
> >>>Hello all,
> >>>
> >>>Has anyone modelled a Single Duct VAV system that takes full 
> >>>      
> >>>
> >fresh 
> >  
> >
> >>>air which moderates all zonal loads through a heat recovery 
unit 
> >>>only?
> >>>
> >>>I received this fatal error...
> >>>
> >>>  **  Fatal  ** ManageControllers: Invalid controller=AHU1 OA 
> >>>CONTROLLER. The only valid controller type for an Air Primary 
> >>>      
> >>>
> >Loop 
> >  
> >
> >>>is CONTROLLER:SIMPLE.
> >>>  ************* Fatal error -- final processing.  More error 
> >>>messages may appear.
> >>>
> >>>I don't have a CONTROLLER:SIMPLE because my AHU does NOT 
contain 
> >>>      
> >>>
> >a 
> >  
> >
> >>>cooling coil or a heating coil. The facility's system designers 
> >>>expect the rotary wheel will moderate all sensible and latent 
> >>>      
> >>>
> >loads 
> >  
> >
> >>>in their entirety. 
> >>>
> >>>Does anyone have any ideas how I could emulate such a system?
> >>>
> >>>Does anyone have an example file of a FULL fresh air system 
with 
> >>>      
> >>>
> >NO 
> >  
> >
> >>>recirc air?
> >>>
> >>>Kind regards
> >>>
> >>>-Elmer
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>The primary EnergyPlus web site is found at:
> >>>http://www.energyplus.gov
> >>>
> >>>The group web site is:
> >>>http://groups.yahoo.com/group/EnergyPlus_Support/
> >>>
> >>>Attachments are not allowed -- please post any files to the 
> >>>      
> >>>
> >appropriate folder in the Files area of the Support Web Site.
> >  
> >
> >>>EnergyPlus Documentation is searchable.  Open EPlusMainMenu.idf 
> >>>      
> >>>
> >and press the "search" button.
> >  
> >
> >>>Yahoo! Groups Links
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> 
> >>>
> >>>      
> >>>
> >
> >
> >
> >
> >
> >
> >
> >The primary EnergyPlus web site is found at:
> >http://www.energyplus.gov
> >
> >The group web site is:
> >http://groups.yahoo.com/group/EnergyPlus_Support/
> >
> >Attachments are not allowed -- please post any files to the 
appropriate folder in the Files area of the Support Web Site.
> >
> >EnergyPlus Documentation is searchable.  Open EPlusMainMenu.idf 
and press the "search" button.
> > 
> >Yahoo! Groups Links
> >
> >
> >
> > 
> >
> >
> >  
> >
> 
> 
> [Non-text portions of this message have been removed]
>






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