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Re: [EnergyPlus_Support] Errors in some zones and not others

To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Subject: Re: [EnergyPlus_Support] Errors in some zones and not others
From: Sam Roose <sam@xxxxxxxxxxxxxxxxxxxxx>
Date: Wed, 19 Apr 2006 18:53:48 +1200
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Thanks for that explanation. I have uploaded my file again  the
temperatures are not converging even with the changes belo and a simpler
system. The file is ³20_SYSTEM_CHANGES.idf. I have also tried putting
temperature limits on the economiser with little change to temperature
convergence and some unexpected results. I am not convinced my autosizing
inputs and the reheat manager are agreeing with each other. The example
files I have found give conflicting information on typical temperatures for
autosizing. Is this where I am going wrong? My main goal at this stage is to
have this system meeting its setpoints with autosized inputs. Thanks in
advance

Sam

On 4/14/06 10:50 AM, "Michael J. Witte" <mjwitte@xxxxxxxx> wrote:

> Sorry, my instructions were not clear regarding the control and setpoint
> nodes. 
> Going back to the original file:
> 
> Original - NODE LIST,
>     Zone 1 Supply Air Temp Nodes,  !- Node List Name
>     Zone 1 Cooling Coil Outlet Node;  !- Node_ID_1
> 
> (Note that this node list was doing nothing in the original file - it was
> never 
> referenced.)
> 
> Modified - NODE LIST,
>     Zone 1 Supply Air Temp Nodes,  !- Node List Name
>     Zone 1 Cooling Coil Outlet Node,  !- Node_ID_1
>     Zone 1 Air Loop Outlet Node; !- Node_ID_2
> 
> Next, we have the set point manager
> 
> Original - SET POINT MANAGER:SINGLE ZONE REHEAT,
>     Zone 1 Air Temp Manager, !- Name
> <snip>
>     Zone 1 Cooling Coil Outlet Node;  !- Name of the set point Node . . .
> 
> Modified - SET POINT MANAGER:SINGLE ZONE REHEAT,
>     Zone 1 Air Temp Manager, !- Name
> <snip>
>     Zone 1 Supply Air Temp Nodes;  !- Name of the set point Node . . .
> 
> This now applies the same set point to two nodes, the node leaving the cooling
> coil *and* the node leaving the heating coil.  The reason you need this is
> because the TEMPandHUMRAT control will lower the setpoint at the node leaving
> the cooling coil when additional dehumidification is required.  The setpoint
> on 
> the heating coil leaving node remains untouched by the humidity controls, and
> so the heating coil knows how much to reheat the overcooled air.
> 
> Then for the controllers, the cooling coil controller should use "Zone 1
> Cooling Coil Outlet Node" as the control node, and the heating coil should use
> "Zone 1 Air Loop Outlet Node" as the control node.  Likewise, of course, for
> the other similar systems.
> 
> Regarding the system configuration, if you intend to have just one zone per
> system, the easiest approach would be to delete the heating coil in the main
> air branch (and its controller) and just let the reheat coil in the SINGLE
> DUCT:CONST VOLUME:REHEAT terminal unit handle all heating and reheating.  Then
> all of the above becomes moot, and the original controls should work fine for
> the cooling coil (assuming the TEMPandHUMRAT fix is in place).  Or keep the
> central heating coil and change the SINGLE DUCT:CONST VOLUME:REHEAT terminal
> units to DIRECT AIR (which does not require and AIR DISTRIBUTION UNIT object).
> 
> Mike
> 
> 
> On 13 Apr 2006 at 17:21, Sam Roose wrote:
> 
>> > Thanks Mike  should have seen the humidity rate issue. I still have the
>> > same errors as before, although I have sent an updated attempt based on the
>> > 5ZoneBoilerOutsideAirReset example file (in terms of the nodes used at
>> > least). This is called ³20_Node_Changes²
>> > 
>> > Referring to reply 2b, my attempts to run a simulation with the separate
>> > single zone reheat node list did not work. I gather the approach is to
>> leave
>> > the existing node list as they are and make a new one for the ³single zone
>> > reheat² control? I am not sure I understand the instructions or the need >>
for
>> > two node Ids in that case.
>> > 
>> > You make a good point about the heating coil within the air loop and the
>> > reheat coil being excessive. Is there an example file with just a cooling
>> > coil and a heating coil in an air loop? I can¹t seem to find one. Thanks >>
for
>> > your help thus far.
>> > 
>> > Sam
>> > 
>> > 
>> > 
>> > On 4/13/06 3:14 AM, "Michael J. Witte" <mjwitte@xxxxxxxx> wrote:
>> > 
>>> > > 
>>> > > 
>>> > > On 7 Apr 2006 at 18:46, Sam Roose wrote:
>>> > > 
>>>>> > >> > I have uploaded a file named 18_manager_changes that when run in
>> > Version
>>>>> > >> > 1.2.3.031 gives me three errors.
>>>>> > >> > 
>>>>> > >> > 1) Calculated design heating load for zone = OUTPATIENT 2 is zero.
>> > Check
>>>>> > >> > zone sizing and zone thermostat inputs.
>>>>> > >> >
>>>>> > >> >     The specification for OUTPATIENT 2 is no different to the other
>> > zones
>>>>> > >> > with respect to zone sizing and zone thermostat inputs. Hopefully,
this
>>>>> > >> > isn't due to the use of multiple air loops.
>>>>> > >> > 
>>> > > 
>>> > > 
>>> > > 1.  This means the zone has no need for heating on the heating design
>>> day.
>>> > > The 
>>> > > zone sizing calculation only relies on the building envelope,
>>> thermostat,
>> > and
>>> > > zone sizing objects.  It knows nothing of the HVAC system at this point
in
>> > the
>>> > > calculation, including any fresh air the HVAC system may be introducing.
>> > So,
>>> > > this is a loads balance issue for the winter design day.  If I'm reading
>> > the
>>> > > drawing and inputs correctly, this zone is a large, part interior, part
>>> > > exterior zone with a small amount of glass.  So this result may be
>> > correct,
>>> > > but 
>>> > > you should double check the internal gains.
>>> > > 
>>> > > The zone loads are used only to determine the air volume flow rate for
>> > that
>>> > > zone.  The system coils are then sized to deliver the specified supply
air
>>> > > temperatures are that flow rate, so the coil load will include the
>>> outside
>> > air
>>> > > loads.
>>> > > 
>>>>> > >> > 2) Maximum iterations exceeded for three different air loops: Zone
7,
>> > Zone
>> > 8
>>>>> > >> > and Zone 23, all quite large zones and mostly internal to the
>>>>> building.
>> > Why
>>>>> > >> > is this?
>>> > > 
>>> > > 2. Max iteration errors indicate the system could not converge on a
>> > solution.
>>> > > This can be due to inconsistent controls causing battling, or a variety
of
>>> > > other reasons.  I see two problems in the controller:simple inputs:
>>> > > 
>>> > > 2a.  There are HUMIDISTAT and SET POINT MANAGER:SINGLE ZONE MAX HUM
>> > objects,
>>> > > so 
>>> > > I presume you want humidity control.  All of the cooling coi controllers
>> > are
>>> > > currently set for Control variable = TEMP.  For humidity control these
>>> must
>> > be
>>> > > set to TEMPandHUMRAT.  They are currently controlling just for the dry
>> > bulb
>>> > > setopint.  (I've posted a suggestion to warn of this condition.)
>>> > > 
>>> > > 2b.  The supply duct heating coil controllers (I'm presuming these are
>> > reheat
>>> > > for the humidity control) are using "Zone 4 Cooling Coil Outlet Node" as
>> > the
>>> > > control node, but that is the air inlet to the coil.  This most likely
why
>>> > > there are max iteration errors and poor control.  To fix this, change
the
>>> > > control node to be the heating coil air outlet node (e.g. Zone 1 Air >>>
Loop
>>> > > Outlet Node).  This node also needs a setpoint.  In the SET POINT
>>> > > MANAGER:SINGLE ZONE REHEAT, the "Name of the set point Node or Node >>>
List"
>>> > > needs 
>>> > > to be a node list which lists both the cooling coil outlet node and the
>> > air
>>> > > loop outlet node (which is the heating coil outlet).
>>> > > 
>>> > > 2c.  I am a bit puzzled at this system configuration.  The way it is
>> > described
>>> > > now, it appears that the cooling coil and heating coil in the main air
>> > loop
>>> > > branch will do all of the control and the zone-level reheat coil is
>>> > > unneccessary.
>>> > > 
>>> > > Mike
>>> > > 
>>> > > 
>>>>> > >> > 
>>>>> > >> > 3) Temperatures out of comfort range, despite everything being
>> > autosized.
>>>>> > >> > Mostly it is a result of overheating due to this building having
high
>>>>> > >> > internal gains. However, the number of hours temperatures are out
of
>> > range
>>>>> > >> > is high in some cases. Can this be reduced?
>>>>> > >> > 
>>>>> > >> > Thanks in advance,
>>>>> > >> > 
>>>>> > >> > Sam Roose
>>>>> > >> > 
>>>>> > >> > 
>>>>> > >> > 
>>>>> > >> > 
>>>>> > >> > 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
>>>>> > >> > 
>>>>> > >> > 
>>>>> > >> > 
>>>>> > >> >  
>>>>> > >> > 
>>>>> > >> > 
>>>>> > >> > 
>>>>> > >> > 
>>>>> > >> > 
>>> > > 
>>> > > 
>>> > > ========================================================
>>> > > Michael J. Witte, GARD Analytics, Inc.
>>> > > EnergyPlus Testing and Support
>>> > > EnergyPlus-Support@xxxxxxxx
>>> > > 
>>> > > 
>>> > > 
>>> > > 
>>> > > 
>>> > > 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
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>>> > > 
>>> > > 
>> > 
>> > 
>> > 
>> > 
>> > [Non-text portions of this message have been removed]
>> > 
>> > 
>> > 
>> > 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
>> > 
>> > 
>> > 
>> >  
>> > 
>> > 
>> > 
>> > 
> 
> 
> ========================================================
> Michael J. Witte, GARD Analytics, Inc.
> EnergyPlus Testing and Support
> EnergyPlus-Support@xxxxxxxx
> 
> 
> 
> 
> 
> 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.
> 
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> "search" button.
> 
> 
> 
> 
> YAHOO! GROUPS LINKS
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> 
> 




[Non-text portions of this message have been removed]



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