Nigusse
commented
6 years ago @lincolnharmer I reviewed the code and the documentation. The code is implemented as designed. I do not see any problem. I also investigated the defect file. Below is my understanding of the issue:
SetpointManager:WarmestTemperatureFlow setpoint manager is intended for setting the cooling supply air setpoint temperature. By design this setpoint manager sets the maximum setpoint value (in this case (35C/95F) when there is tiny or zero cooling load. What is happening in this defect file is that the maximum setpoint value is used when there is no cooling load at 9 AM and 11-12 PM hours and the supply fan is ON from 9 through 24 hours (per the schedule "Schedule Day 1"). Since the supply fan was ON, the heating coil heats the air to the heating setpoint temperature of 35C/95F even if there was no load. As the result you have spikes in "Zone Air System Sensible Heating Energy" report variable value whenever there is tiny or no cooling load and the supply fan is ON. This is the untended consequence of using HIGH value for Maximum Setpoint Temperature. It is recommended to enter mild maximum setpoint temperature value (say 16C-19C) and use an air terminal with reheat object or add ZoneHVAC heating equipment to handle the heating load for each zone as needed.
Issue overview
when using the SetpointManager:WarmestTemperatureFlow with the Control Variable set to "Temperature" and the strategy set to "TemperatureFirst", heating energy is being significantly over estimated because the airloop using the SetpointManager:WarmestTemperatureFlow are requesting heat when the fan turns on and also right before the fan turns off regardless of zone temperature and the heating setpoint.
See IDF and timeseries data for one of the zones attached. All other zones with this setpoint manager were found to behave the same way. The upper blue line is the sensible heat output being provided to the zone which can be seen spiking every morning and afternoon even though the zone heating temperature setpoint (maroon line) is always well below the zone air temperature (orange line). The black line is the node temperature where the setpoint manager is located (discharge of AHU). For some reason it is spiking to the maximum allowed temperature setpoint (95F) whenever the AHU turns on and right before it turns off based on the fan schedule.
This behavior happens everyday even in the middle of summer when outdoor drybulb never falls below 70F. No humidity control is being used in this model...
files.zip