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Issue with Multiple HVAC templates in one zone

asked 2017-07-10 06:16:37 -0500

Ali Raad gravatar image

updated 2017-07-11 02:50:42 -0500

I am trying use HVAC templates in my model. Currently I am using the FANCOIL template. In my model I have some Zones that have 2 fan coil units. When I use the the templates and I define 2 fan coil units in one zone I get the following errors:

      ** Warning ** Output:PreprocessorMessage="ExpandObjects" has the following Warning conditions:
   **   ~~~   ** Repeated name found: 35DD03 found as the name of more than one
   **   ~~~   ** HVACTemplate:Zone:FanCoil object.
   ** Warning ** Output:PreprocessorMessage="ExpandObjects" has the following Warning conditions:
   **   ~~~   ** The same name is used for multiple HVACTemplate:Zone:* objects: 35DD03.
   **   ~~~   ** Names must be unique across all HVACTemplate:Zone:* objects.
   ** Severe  ** Branch Name, duplicate name=35DD03 COOLING COIL CHW BRANCH
   ** Warning ** Node used as an inlet more than once: 35DD03 COOLING COIL CHW INLET
   **   ~~~   **   Used by     : BRANCH, name=35DD03 COOLING COIL CHW BRANCH
   **   ~~~   **   as inlet for: COIL:COOLING:WATER, name=35DD03 COOLING COIL
   **   ~~~   **   and  by     : BRANCH, name=35DD03 COOLING COIL CHW BRANCH--dup
   **   ~~~   **   as inlet for: COIL:COOLING:WATER, name=35DD03 COOLING COIL
   ** Warning ** Node used as an outlet more than once: 35DD03 COOLING COIL CHW OUTLET
   **   ~~~   **   Used by     : BRANCH, name=35DD03 COOLING COIL CHW BRANCH
   **   ~~~   **   as outlet for: COIL:COOLING:WATER, name=35DD03 COOLING COIL
   **   ~~~   **   and  by     : BRANCH, name=35DD03 COOLING COIL CHW BRANCH--dup
   **   ~~~   **   as outlet for: COIL:COOLING:WATER, name=35DD03 COOLING COIL
   ** Severe  ** Branch Name, duplicate name=35DD03 HEATING COIL HW BRANCH
   ** Warning ** Node used as an inlet more than once: 35DD03 HEATING COIL HW INLET
   **   ~~~   **   Used by     : BRANCH, name=35DD03 HEATING COIL HW BRANCH
   **   ~~~   **   as inlet for: COIL:HEATING:WATER, name=35DD03 HEATING COIL
   **   ~~~   **   and  by     : BRANCH, name=35DD03 HEATING COIL HW BRANCH--dup
   **   ~~~   **   as inlet for: COIL:HEATING:WATER, name=35DD03 HEATING COIL
   ** Warning ** Node used as an outlet more than once: 35DD03 HEATING COIL HW OUTLET
   **   ~~~   **   Used by     : BRANCH, name=35DD03 HEATING COIL HW BRANCH
   **   ~~~   **   as outlet for: COIL:HEATING:WATER, name=35DD03 HEATING COIL
   **   ~~~   **   and  by     : BRANCH, name=35DD03 HEATING COIL HW BRANCH--dup
   **   ~~~   **   as outlet for: COIL:HEATING:WATER, name=35DD03 HEATING COIL
   ** Severe  ** GetBranchInput:  Invalid Branch Input, preceding condition(s) will likely cause termination.
   ** Severe  ** AuditBranches: There are 2 branch(es) that do not appear on any BranchList.
   **   ~~~   ** Use Output:Diagnostics,DisplayExtraWarnings; for detail of each branch not on a branch list.
   ** Severe  ** DesignSpecification:OutdoorAir Name, duplicate name=SZ DSOA 35DD03
   **  Fatal  ** GetOARequirements: Errors found in input.  Preceding condition(s) cause termination.

So is there anyway to overcome the issue of duplicated names, to be able to define more than template in one zone?

The other thing when I use the fan coil during winter it works perfectly and it heats the zone to the desired temperature, but in Summer it dose not show that much effect, although the cooling coil is always on in summer and the heating coil is off it still dose not cool the zone to the desired temperature. I am using District Cold Water and the Supply Air Maximum Flow Rate is set to be autosize. Any suggestions regarding that issue?

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answered 2017-07-10 15:21:21 -0500

updated 2017-07-11 02:50:50 -0500

For those zones with multiple fan coil units, I would suggest modeling both the fan coil units as a single component in EnergyPlus. You should be able to add the capacities of the coils for all the FCUs in a zone to size the coil of the aggregated coil. If you are autosizing, then you need not worry about adding up the coil capacities.

With regard to unmet cooling loads, I suggest that you thoroughly verify all your internal gains, envelope properties and all schedules. This issue most commonly occurs when the Schedules for internal gains and thermostats do not match. If you still have unmet cooling loads after all the checks, then you should verify that your model is using accurate cooling capacities and that all the cooling components are actually operating when desired.

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Hello @rsunnam

Thank you very much fro your answer, I really appreciate your help.
Regarding the modeling 2 fan coil units as one unit instead of two. could you please elaborate more on that. Because when I look at the HVACTEMPLATE:FANCOIL I do not find any field to define the coil capacity. I guess because when using templates the capacity of the coil will be autosized. Is there a way to add it that I do not know about?.

Ali Raad gravatar imageAli Raad ( 2017-07-10 16:09:28 -0500 )edit

If the templates do autosize the capacity of the coil, then what I can do is to sum the Supply Air Maximum Flow Rate of both unites and define it in the templates so E+ would autosize the coils capacity. Please correct me if I'm wrong.

I have noticed that the issue of the cooling was solved when I defined the Supply Air Maximum Flow Rate using the manufacture data instead of autosize.

Thank you

Ali Raad gravatar imageAli Raad ( 2017-07-10 16:09:49 -0500 )edit

@Ali Raad Your approach to use the aggregated max supply air flowrate would work fine. The EnergyPlus Input/Output reference guide clearly explains all the fields for the HVACTemplate:FanCoil component. Did you get a chance to look at this? Just make sure that all the other fields are correctly filled out. You can also refer to an E+ example file for guidance (i.e. in case you haven't already looked at it).

rsunnam gravatar imagersunnam ( 2017-07-10 16:33:04 -0500 )edit

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Asked: 2017-07-10 06:16:37 -0500

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Last updated: Jul 11