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[EnergyPlus_Support] Problems with fancoil simulations
Thank you Michael for your suggestions.
I have monitored coil operation with the report variables "Total Water Heating Coil Rate" and "Total Water Cooling Coil Rate". In a winter simulation, when the system starts up (Monday, 8:00 AM) there is a quick rise of heatring coil energy and afterwards energy returns to zero and continues zero the entire simulation. The same energy curve occurs in a summer simulation for the cooling coil rate.
Do you know how to explain this effect?
(I have changed thermostat controls to dual setpoint with deadband and the same results were obtained).
Pedro Manuel Rodrigo Cruz
Universidad de Jaén
Michael J. Witte wrote:
Thank you to Miguel for offering to review the input file. I have two
suggestions:
1. Be sure to read the definition of "Zone/Sys sensible heating rate" and
"Zone/Sys sensible cooling rate" in the Input Output Reference. If the fan
coils have outside air flow, "Zone/Sys sensible cooling rate" may not always
mean that the cooling coil is operating, it may just be cold outside air
flowing into the zone. Note that fan coils in EnergyPlus run with continuous
fan whenever the unit is scheduled on. Add these report variables to monitor
coil operation:
Total Water Heating Coil Energy
Total Water Cooling Coil Energy
2. In version 1.4, changes were made to the fan coil unit controls to provide
better control at low load conditions when the outside air may need to be
tempered. These controls rely on knowing both a heating and cooling setpoint.
I would recommend trying the dual setpoint with deadband thermostat controls
and let the heating and cooling coil schedules control the availability.
Mike
On 11 Dec 2006 at 19:34, Pedro Rodrigo wrote:
> Hi all:
> I´m trying to model a two-pipe fancoil system in a mono-zone building model.
> I´m using the "fancoilautosize" example as a reference.
> The "fancoilautosize" example uses a "fancoil unit:4 pipe" object, a chilled
> water loop linked to the cooling coil and a hot water loop linked to the
> heating coil. I´m trying to modify the availability schedules in order to
> supply heating only in winter season and cooling only in summer season
> (cooling coil and chilled water loop must be off in winter - heating coil and
> hot water loop must be off in summer).
> I have launched weather file simulations and results reported in the variables
> "Zone/Sys sensible heating rate" and "Zone/Sys sensible cooling rate" show
> that the system is supplying heating and cooling in both summer and winter
> seasons. The zone temperature (variable "Zone mean air temperature" ) does not
> follow the zone setpoints.
> The following schedules have been used in my simulations:
> - FanAndCoilAvailSche d uses the same scheme for the hole year: it is ON from
> 8:00 AM to 9:00 PM (Monday to Friday) and OFF on weekend. The same schedule is
> used for the objects "fancoil unit:4 pipe", "fan:simple: const volume",
> "coil:water: cooling" and "coil:water: simpleHeating" .
> - The Zone Control Type Sched is set to 1 in winter season (single heating
> setpoint) and 2 in summer season (single cooling setpoint). It is used in the
> "zone control: thermostatic" object.
> - The chilled water loop operation scheme uses an Availability Schedule that
> is OFF in winter season and ON in summer season.
> - The hot water loop operation scheme uses an Availability Schedule that is ON
> in winter season and OFF in summer season.
> Does anybody know where is the problem?
>
>
> Pedro Manuel Rodrigo Cruz
> Universidad de Jaén
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