Carrier VAV Zone II Installation And Startup Manual page 59

The Master gathers data from the slave zone controllers such as occupancy status, setpoints, and zone
1
temperature.
The Master performs mathematical calculations and algorithms on the data.
2
The Master sends the composite information to the air source.
3
The air source returns information such as mode, supply air temperature, and outside air temperature, if
4
present.
The Master passes that information to all slave zone controllers.
5
The following sections detail the process for VAV Systems and VVT Systems.
VAV Systems
The VAV Master continuously scans the system and gathers the following information from each zone:

Setpoints and zone temperature

Zone size

Occupancy status

Damper position

RH and CO
The VAV Master then does the following calculations and sends the results to the air source.

If any zone is occupied, the system's occupancy status is set to occupied.

If the system is occupied, it averages the space temperatures from all occupied zones using their normal
terminal size at 1" (.249 kpa) VP to apply a weighting factor to that average (OCCSPT).

It performs this same weighted average space temperature calculation for all the zones in the system (SPT).

If no zone is occupied, it sets the occupied space temperature to "?". ("?" only displays on the Details tab of
the Collector microblock and the Linkage status section of the Properties page.

It calculates 4 weighted average setpoints:

the occupied heating weighted average setpoint (OHSP)

occupied cooling weighted average setpoint (OCSP)

the weighted average unoccupied heating setpoint (UHSP)

unoccupied cooling setpoint (UCSP).

If the zones supply CO
configuration for each.
The air source determines its operating mode from the information received, and then sends the following to the
Master:

Air source mode

Supply air temperature

Outside air temperature

Static pressure (if applicable)
The air source verifies the mode by comparing its supply air temperature to the space temperature received
through linkage. See the air source documentation for operation and parameters used to verify its mode. This
verification allows the system to verify that the stated air source mode is actually being provided. For example, if
the air source heat has failed, the air source's actual mode would not indicate heat unless that mode was verified
by the equipment's supply air temperature.
The VAV Master continuously evaluates all zones and processes their data as described above. The system
switches modes only if the equipment mode changes.
VAV Zone II Controllers
Installation and Start-up Guide
values (if applicable)
2
or RH values, it calculates either a maximum or average value as determined by the
2
55
Sequence of operation
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