Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
The setpoint manager object SetpointManager:Scheduled:DualSetpoint is the wrong choice for an air loop. From the Input/Output reference for that object: "Currently the DualSetpoint Manager will be used with PlantLoop when the Plant Loop Demand Calculation Scheme is set to DualSetpointDeadband". When applied to an air loop, the DualSetpointManager will not control air temperature between the two setpoints, it will set the air temperature to the average of the scheduled high and low temperatures. This supply temperature likely does not match the zone, loop and terminal sizing parameters, causing the unmet hours.
VAV with reheat systems are usually controlled at the central air handling unit to a cool deck temperature (usually 55F), and the terminal units will re-heat the supply air to meet the zone thermostat temperature. You should make sure that the air loop and zone terminal units have sizing parameters that match their control operation, so the equipment will have enough capacity to meet the zone loads. See the answers to this post for more general tips on reducing unmet hours.
