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RE: [EnergyPlus_Support] Chiller won't shut off for cool seasons

This air handler has a setpoint manager for the supply air deck temperature that is totally separate from the thermostats in the zone.  Whenever the air handler is running it will run the cooling coil to target a deck temperature of 12.8C and thereby load the chiller.   


From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of HJ
Sent: Friday, October 26, 2012 4:39 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Chiller won't shut off for cool seasons



I just changed the setpoint to 27 C and still the chiller is running when air temperature is 19 C. I also noticed the idf file in the email is wrong. I attached the new idf file and the output file here. The output file contains the room air temperature, setpoint temperature and chiller energy consumption

On 10/26/2012 6:24 PM, HJ wrote:


Thanks Jeremiah. It seems to be the case. Since the difference between room air temperature and setpoint for chiller is less than 2 C.


On 10/26/2012 6:02 PM, Jeremiah Crossett wrote:


You could use an availability schedule that turns off during days/hours you do not want cooling and call it from the thermostat object. The concern with this approach is that your zone may actually be above your 23c. You might want to try it with your availability schedule to turn off the chiller during cold seasons,  and then plot the output variable for well mixed zone air temperature to see if the temperatures are above 23C..  If they are above 23, than that would explain why the chiller was on..

If you are not using the thermostat type "dual setpoint with deadband" than you may have an issue where your heating and cooling are in a battle. You may wish to use this type of thermostat for all models, and have a deadband of at le


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