[EnergyPlus_Support] Re: SetpointManager:MixedAir and Economizer question

["Jean marais" <jeannieboef@xxxxxxxxx>]

Dear James,
What is actually happening here? Does the ODAManager use all the setpoints in the setpoint list simultaniously? I understand it this way that it sets a setpoint on a node (which node? can I assign it) by looking at the setpoint (that must be previously set by another setpoint manager) set on the reference node and then compares it to the setpoint node (or node list, and this is where I stop understanding) and then figures out at what temperature to apply its setpoint (at the exit of the Mixing box, right?) to best achieve the reference setpoint temperature as set.

by including the setpoints of the htg and clg coil outlets, the user is saying, watch out I'm still going to cool to this temperature and then heat to this temperature. Does it know that I'm in heating or cooling mode? Do setpoint managers generally care about heating or cooling modes?



--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jim Dirkes" <jim@...> wrote:
>
> Dear Matthew,
> 
> .         The reference set point node is almost universally the outlet node
> of the air loop.  It is never the room node.
> 
> .         For the set point node or node list, I use a NodeList which
> contains all outlet nodes of components upstream of the fan, starting with
> the mixed air node. 
> 
> .         Examples are shown below
> 
>  
> 
> 
>  
> 
> SetpointManager:MixedAir
> 
> 
> Name
> 
> SPMgr_MixAir_PropDOASwPTHP
> 
> 
> Control variable:
> 
> Temperature
> 
> 
> reference set point node name
> 
> NodeOut_AHU_PropDOASwPTHP
> 
> 
> fan inlet node name
> 
> NodeOut_HtgCoilAir_PropDOASwPTHP
> 
> 
> fan outlet node name
> 
> NodeOut_AHU_PropDOASwPTHP
> 
> 
> Name of the set point Node or Node List
> 
> MANodeLIST_PropDOASwPTHP
> 
>  
> 
> 
>  
> 
> NodeList
> 
> 
> Name
> 
> MANodeLIST_PropDOASwPTHP
> 
> 
> Node Name1
> 
> NodeOut_MA_PropDOASwPTHP
> 
> 
> Node Name2
> 
> NodeOut_ClgCoilAir_PropDOASwPTHP
> 
> 
> Node Name3
> 
> NodeOut_HtgCoilAir_PropDOASwPTHP
> 
>  
> 
> Economizers do not (normally) operate in the way that you describe.
> 
> .         They do maintain a minimum amount of outdoor air during all
> occupied periods.  This is rarely zero.
> 
> .         They do allow more outdoor air when needed for cooling, but the
> amount of outdoor air is not necessarily a linear relationship based on
> outdoor air temperature.  Rather it is the amount of outdoor air need to
> maintain
> 
> o   The discharge air SetpointManager setpoint or
> 
> o   The zone temperature setpoint
> 
> o   Depending on the type of air loop that is in use
> 
> .         There are several possible limits, such as outdoor temperature or
> enthalpy which, when exceeded, cause the outdoor air amount to return to the
> minimum value until the limit is no longer exceeded.
> 
> This is an important object to understand, so it is good that you are
> investigating it carefully!
> 
>  
> 
> Typical Controller:OutdoorAir shown below:
> 
> 
>  
> 
> Controller:OutdoorAir
> 
> 
> Name
> 
> OAController_PropDOASwPTHP
> 
> 
> Relief Air Outlet Node Name
> 
> NodeOut_EA_PropDOASwPTHP
> 
> 
> Return Air Node Name
> 
> NodeIn_RA_PropDOASwPTHP
> 
> 
> Mixed Air Node Name
> 
> NodeOut_MA_PropDOASwPTHP
> 
> 
> Actuator Node Name
> 
> NodeIn_OA_PropDOASwPTHP
> 
> 
> Minimum Outdoor Air Flow Rate
> 
> .47
> 
> 
> Maximum Outdoor Air Flow Rate
> 
> 1.51
> 
> 
> Economizer Control Type
> 
> FixedDryBulb
> 
> 
> Economizer Control Action Type
> 
> ModulateFlow
> 
> 
> Economizer Maximum Limit Dry-Bulb Temp (C)
> 
> 21.1
> 
> 
> Economizer Maximum Limit Enthalpy (J/kg)
> 
>  
> 
> 
> Economizer Maximum Limit Dewpoint Temp (C)
> 
>  
> 
> 
> Electronic Enthalpy Limit Curve Name
> 
>  
> 
> 
> Economizer Minimum Limit Dry-Bulb Temp (C)
> 
>  
> 
> 
> Lockout Type
> 
> NoLockout
> 
> 
> Minimum Limit Type
> 
> FixedMinimum
> 
> 
> Minimum Outdoor Air Schedule Name
> 
> SchCpct_AlwaysOn
> 
> 
> Minimum Fraction of Outdoor Air Schedule Name
> 
> 	
> 
> Maximum Fraction of Outdoor Air Schedule Name
> 
> 	
> 
> Mechanical Ventilation Controller Name
> 
> 	
> 
> Time of Day Economizer Control Schedule Name
> 
> 	
> 
> High Humidity Control
> 
> 	
> 
> Humidistat Control Zone Name
> 
> 	
> 
> High Humidity Outdoor Air Flow Ratio
> 
> 	
> 
> Control High Indoor Humidity Based on Outdoor Humidity Ratio
> 
> 	
> 
> Heat Recovery Bypass Control Type
> 
> 	
> 
>  
> 
>  
> 
>  
> 
> The Building Performance Team
> James V. Dirkes II, P.E., BEMP , LEED AP
> 1631 Acacia Drive NW
> Grand Rapids, MI 49504
> 616 450 8653
> 
>  
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of ntraughpee
> Sent: Monday, November 28, 2011 5:34 PM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] SetpointManager:MixedAir and Economizer
> question
> 
>  
> 
>   
> 
> Firstly, I have a question regarding how exactly to use the
> SetpointManager:MixedAir function. There are 4 separate node names that it
> is asking for after the name/control variable. They are
> 
> 1. Reference Setpoint Node Name
> 2. Fan Inlet Node Name
> 3. Fan Outlet Node Name
> 4. Setpoint Node or Nodelist Name
> 
> Now, The fan inlet/outlet are easy enough but I am confused as to what
> exactly is meant by the Reference Setpoint Node nmae. It says it is where
> the system supply air temperature is set and that this is normally the
> AirLoopHVAC outlet node, but I am a little curious as to where this is. It
> looks like that in the I/O example that it is listed as Air Loop Outlet Node
> which is then under the NodeList "Supply Air Temp Nodes" which is then
> listed as the setpoint for a single zone reheat. So is this reference node
> the room temperature setpoint you are trying to maintain? Is the "Setpoint
> Node or NodeList Name" supposed to be the node where the air is mixed (as in
> the mixed air outlet)?
> 
> Furthermore, on another note I have a building where the pneumatic
> "economizer" is set up so that it the logic basically has it operating where
> the FA damper is closed at some minimum temperature, then opens to a %
> relating to the temperature over some range until it is 100% FA at some max
> temperature. That is to say the FA Damper is @ 0% @ 55 degrees F up until
> 100% @ 85 degrees F where the range is linear between the two points. What
> is the best way to do this?
> 
> 
> 
> Reply to
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