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[EnergyPlus_Support] Re: SetpointManager:MixedAir and Economizer question
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad <RRaustad@...> wrote:
>
> The reference node must have a setpoint assigned to it by another
> setpoint manager.
>
> Of course it does, that's why it's called a reference. Use a different
> type of set point manager to put a set point on a node (remember, the
> fan inlet node, return node, etc.). Then used the mixed air set point
> manager to read the reference node set point, adjust for fan heat, and
> place a new set point anywhere you need it (usually at a coil outlet node).
>
>
> On 12/1/2011 1:43 PM, Jean marais wrote:
> >
> > After reading the io Ref. your suggestion did not make much sense. I
> > applied it anyway and got the errors that I thought I would get.
> >
> > The reference node must have a setpoint assigned to it by another
> > setpoint manager.
> >
> > The setpoint nodes are all the nodes to which the
> > SetpointManager:MixedAir will assign the new calculated setpoint to.
> >
> > This means the Reference Node should have a setpoint assigned by
> > another manager = air delivery temperature (which should change for
> > the heating and cooling case), as this is the setpoint which you are
> > trying to hit.
> >
> > And none of the nodes in the SetpointNodeList may be set by other
> > setpointmanagers as they will conflict.
> >
> > In my current configuration I have Mixingbox,[Fan,dx cooling coil],hot
> > water coil. With setpoint managers for cooling at the dx outlet node
> > (12°C) and at the heating coil outlet (-99 to 34°C). The Setpoint
> > assigned at the exit of my htg coil doubles as my delivery air
> > setpoint temp and serves as the reference node for the
> > SetpointManager:MixedAir. My SetpointManager:MixedAir Setpoint is only
> > assigned to the exit of the Mixing box (but could also be assigned to
> > the exit of the fan.)
> >
> > I think James and I understand this object differently.
> >
> > Pointers? Comments?
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> > <RRaustad@> wrote:
> > >
> > > 1) put the reference node on any node that will not be controlled, use
> > > the return node if you have to, or the fan outlet would also work
> > > 2) don't worry about upstream and downstream, just enter the fan
> > > inlet/outlet node names and the manager will do the rest
> > >
> > > What you are basically doing is calculating a set point at the
> > reference
> > > node, and then using the mixed air manager to adjust that calculated
> > set
> > > point by the fan heat. So when all is said and done, the outlet of the
> > > air loop is at the same temperature as the reference node set point
> > > temperature
> > >
> > > On 11/29/2011 11:50 AM, Jean marais wrote:
> > > >
> > > > Thanks James. A few more questions, if you'll indulge me...
> > > >
> > > > The referance node:
> > > > I assume one must be quite careful as to what setpoint is used on the
> > > > reference node (usually the last node on the supply side). For
> > > > example, if my last componant is a heating coil, I can't assign a
> > > > fixed schedule 32degC with a setpoint manager on the htg coil exit
> > > > node, if I plan heating and cooling all year round. I need to use, in
> > > > this case a setpoint manager that can decrease the setpoint on this
> > > > node during times of cooling. Right?
> > > >
> > > > The other setpoint nodes in the list:
> > > > How does the MixedAirSPmanager "know" on which node the fan sits, to
> > > > deturmine upstream and down stream from it? I don't have it here. Is
> > > > it an input field? I ask, because not just the fan takes or adds to
> > > > the air stream. Maybe, it just looks at the setpoint on each node in
> > > > the list (not the airstream temp), checks if it must be applied (eg.
> > > > clg sp not applied if in heating mode), and estimates the energy put
> > > > in or out at these nodes. Using this information, it sets the
> > setpoint
> > > > at the exit of the mixing box, then the controller tries to control
> > > > the damper to match. Right?
> > > >
> > > > Please explain "exception 1". My guess is that if the downstream htg
> > > > coil exit node was included, the manager would see it as a second fan
> > > > and (if outside had cold air) possibly introduce more than nessecary
> > > > ODA, which the poor htg coil would have to heat up. This all becomes
> > > > hellishly complicated considering econimizers and other factors.
> > > >
> > > >
> > >
> > > --
> > > 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
> > >
> >
> >
>
> --
> 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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