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Re: [EnergyPlus_Support] PlantFlowResolver error -- "Branch flow rates out of bounds"
It appears from the output (csv) file that the PTAC water heating coil
in zone 513_computer is operating. Please disregard these warnings
unless you find good reason to suspect it affects the simulation
results. From the report variables you selected, you did a very good job
of troubleshooting the warnings. These report variables confirm the unit
is operating correctly. I did not look closely at the plant loop to see
if the warnings indicate a problem with the flow rate through the plant.
To check the plant operation, report out all hot water coil (and bypass)
outlet node flow rates and compare the sum of these to the hot water
pump flow rate. Also compare pump water flow rate with the boiler (and
bypass) flow rate.
We will look into resolving this issue.
Richard Raustad wrote:
> You will have to upload your file so we can take a look.
>
> Josh K wrote:
>>
>> Hi Richard/Brent;
>>
>> I double checked, and the heating coils are on ACTIVE branches that
>> are in
>> parallel with a demand bypass branch. Any other suggestions as to
>> what might
>> be the problem?
>>
>> Thanks,
>>
>> Josh
>>
>> On Feb 4, 2008 9:12 AM, Griffith, Brent <brent_griffith@xxxxxxxx
>> <mailto:brent_griffith%40nrel.gov>> wrote:
>>
>> > Check that the hot water coils are on a plant loop branch with
>> "ACTIVE"
>> > control and that there is a bypass in parallel with them.
>> >
>> > ________________________________
>> >
>> > From: EnergyPlus_Support@xxxxxxxxxxxxxxx
>> <mailto:EnergyPlus_Support%40yahoogroups.com><EnergyPlus_Support%40yahoogroups.com>
>>
>> > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx
>> <mailto:EnergyPlus_Support%40yahoogroups.com><EnergyPlus_Support%40yahoogroups.com>]
>>
>> > On Behalf Of josh_miarch
>> > Sent: Saturday, February 02, 2008 4:57 PM
>> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
>> <mailto:EnergyPlus_Support%40yahoogroups.com><EnergyPlus_Support%40yahoogroups.com>
>>
>> > Subject: [EnergyPlus_Support] PlantFlowResolver error -- "Branch flow
>> >
>> > rates out of bounds"
>> >
>> > I'm attempting to simulate a large, multizone building, and I'm
>> > encountering the following warning message:
>> >
>> > ** Warning ** PlantFlowResolver: Branch flow rates out of bounds, for
>> > Plant Loop=PLANT, Branch=514_COMPUTER_FC_HEATING_COIL_BRANCH
>> > ** ~~~ ** Conditions should be: 0.000 <= 1.517E-002 <= 0.000
>> >
>> > Over the course of an annual simulation, there are enough of these
>> > warnings (>30 000) to result in a fatal error that crashes the
>> > simulation.
>> >
>> > The branch in question is the heating coil branch for a
>> > PACKAGEDTERMINAL:AIRCONDITIONER object. Both the coil and the
>> > PACKAGEDTERMINAL:AIRCONDITIONER are available when these warnings are
>> > occurring.
>> >
>> > I've noticed that this error tends to occur largely in the shoulder
>> > seasons, when there is a relatively large amount of heating required
>> > in the morning (as there are relatively low external temperatures, and
>> > the zone thermostat switches from the the night set-back temperature
>> > of 16 C to 20 C), and then cooling required later in the day (as the
>> > combination of higher exterior temperatures and high internal gains
>> > adds heat to the zone). Although the load on the heating coil is
>> > relatively large in the morning and the PTAC object doesn't have a
>> > field for specifying max HW flowrates, the flow that I am seeing to
>> > coil is definitely reasonable, which makes this error more
>> perplexing...
>> >
>> > Any help would be greatly appreciated.
>> >
>> > Josh
>> >
>> > [Non-text portions of this message have been removed]
>> >
>> >
>> >
>>
>> --
>> Josh Kjenner, EIT, LEED AP
>> Manasc Isaac Architects Ltd.
>> 10225 100 Avenue :: Edmonton, AB T5J 0A1
>> 780.429.3977
>>
>> [Non-text portions of this message have been removed]
>>
>>
>
--
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
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