A room specified here, which must be one of the rooms served by the Apache System, will be treated as the master room for that system, dictating whether heating and cooling are available to other rooms served by the system (the ‘slave rooms’). A room is said to be served by the system if the system is assigned to that room in the ‘System’ field on the Space Data System tab. The rules applying to this mode of control are as follows.
Master zone control only applies only to rooms using the ApSys system methodology. It operates when the Master zone is assigned, and only during simulation, not during Loads analyses.
For rooms using the ApHVAC system methodology the role of Master zone is played by the Master room assigned to each HVAC zone.
When the master zone receives heat from the system the system is said to be in heating mode. It then remains in heating mode after it ceases to receive heat, until such time as the master zone receives cooling. It then switches to cooling mode, and it remains in cooling mode until the master zone next receives heat, and so on. At the start of a simulation the state of the system is initialised to heating mode.
In situations where master zone control applies:
When the system is in heating mode, the slave zones may receive heat (as dictated by their set points and heating availability profiles) but they may not receive cooling.
When the system is in cooling mode, the slave zones may receive cooling but they may not receive heat.
Rooms may only be dehumidified when they are also being cooled. No such constraint applies to humidification.
