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# Control of AHU with one heating coil for multiple zones?

Hi

I'm simulating in EnergyPlus and I'm using ventilation as a secondary heating/cooling component next to my TABS. I have one AHU with a heating and cooling coil that is connected to 15 zones with different temperature demand. Let's say in winter I'm heating the different zones but one zone will reach its desired temperature quicker because of solar gains. What will the heating coil in the AHU do? Will it stop heating the air to the different zones or will it keep heating with the same air supply temperature till all the zones met their desired temperature? Or will it do something else? Also I have no heating coils placed in the different zones, only in my AHU. I am using the ThermostatSetpoint:DualSetpoint (20-24°C) and the SetpointManager:Scheduled:Dualsetpoint. Thanks in advance!

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This sounds like a VAV system without terminal reheat. For this system type the main coils will be controlled based on a coil outlet air set point temperature. Several of the set point managers will work (e.g., SetpointManager:Scheduled, SetpointManager:OutdoorAirReset, SetpointManager:SingleZone:Reheat, etc.) and you may want to use a heating SPM for the heating coil and cooling SPM for the cooling coil. I haven't used the DualSetPoint SPM but will suggest reporting the System Node Setpoint Temperature wherever this SPM is used to make sure the coils control to the correct set point (see below). Regarding the zones, as the zones meet the zone thermostat set point temperature the VAV box damper should close. Depending on the minimum stop setting in the terminal box, the damper may close all the way or only close to some minimum setting. If the damper remains open then the zone temperature will exceed the zone thermostat temperature set point. Regarding the main coils, if there is air flow through the coils (i.e., any dampers are open) then the coils will try to meet the coil outlet temperature set point.

Output:Variable,"Node Name",System Node Setpoint Temperature,TimeStep;
Output:Variable,"Node Name",System Node Setpoint High Temperature,TimeStep;
Output:Variable,"Node Name",System Node Setpoint Low Temperature,TimeStep;

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