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How to model an hydronic heating system -boiler + radiators- in OpenStudio?

asked 2015-05-22 09:03:57 -0500

claudi.alanis gravatar image

updated 2015-07-12 14:30:25 -0500

Hello building energy modeling professionals,

I am trying to run a very basic simulation of an hydronic heating system in a small building with two thermal zones. The building does not have mechanical ventilation nor cooling. I have modeled in openstudio a plant loop with boiler linked to baseboard hot water heating coils for each thermal zone and a setpoint manager scheduled with constant hot water temperatures. In the thermal zones section i have applied the zone equipment linked to the plant loop and i have specified a heating thermostat scheduled based on the hot water temperature profile i created. The temperature schedule of the heating thermostat schedule in the thermal zone section matches with that of the set point manager in the plant loop.

Regardless of the simplcity of the model, i always get the following error when running the simulation:

Completed Initializing Surface Heat Balance
Calculate Outside Surface Heat Balance
Calculate Inside Surface Heat Balance
Calculate Air Heat Balance
Initializing HVAC
**FATAL:Errors getting Zone Control input data.  Preceding condition(s) cause termination.
EnergyPlus Run Time=00hr 00min  2.00sec

The specific FATAL errors shown in the eplusout.err file are:

** Severe  ** ThermostatSetpoint:DualSetpoint="THERMOSTAT SETPOINT DUAL SETPOINT 1" invalid Cooling Setpoint Temperature Schedule Name="" not found.
   ** Severe  ** ThermostatSetpoint:DualSetpoint="THERMOSTAT SETPOINT DUAL SETPOINT 2" invalid Cooling Setpoint Temperature Schedule Name="" not found.
   ** Severe  ** GetStagedDualSetpoint: Errors with invalid names in ZoneControl:Thermostat:StagedDualSetpoint objects.
   **   ~~~   ** ...These will not be read in.  Other errors may occur.
   **  Fatal  ** Errors getting Zone Control input data.  Preceding condition(s) cause termination.

Hence i cannot complete the simulation.

I don't know how/where to fix those cooling setpoints... i have not specified any cooling as the building itself has no mechanical cooling.

Please, if someone can help me out running this simple model i will really appreciate it. Thank you very much!

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Did you specify the Cooling thermostat schedule? I believe this is a must even if there is no cooling system. I usually specify a temperature that is excessively high. (Ie. the thermostat never sees a load that exceeds this, thus no cooling demand is present.)

nfonner gravatar imagenfonner ( 2015-05-22 09:30:26 -0500 )edit

@nfonner is right, you need both a heating and cooling schedule in the zone thermostat. Since you don't have cooling equipment, the only thing the cooling setpoint schedule will be used for is determining unmet hours, so you may want to set the schedule to a high temp to avoid irrelevant hours.

aparker gravatar imageaparker ( 2015-05-23 11:17:16 -0500 )edit

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answered 2015-05-24 09:17:39 -0500

claudi.alanis gravatar image

Thank you very much for your answers. Certainly, i had to specify a cooling schedule in the thermostats even when no cooling is present in the building.

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Asked: 2015-05-22 09:03:57 -0500

Seen: 864 times

Last updated: May 24 '15