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[EnergyPlus_Support] Re: SetpointManager:MixedAir and Economizer question

What exactly constitutes the "air loop"? Is it from the Economizer outlet to the first of the heating/cooling coils?

The system I am currently working on in particular is a dual duct with a blow thru fan which sits right after the mixer. Then right after the fan sits a splitter which sends the air to the heating coil/cooling coil. The heating side is then split into 3 separate branches which go to each zone and the cooling side is also split into 3 separate branches which go to each zone. 

Where would I want my reference node and setpoint node list to contain? Haha, excuse my ignorance but I am kind of looking to have my hand held here and try to construct and over arching mental framework for this one and the I/O reference has been of little to no help.

--- 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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