Sequence of operation
Occupied mode
• When the zone temperature is between the occupied heating and cooling setpoints inside of
the bias, the primary air damper is at the minimum flow setpoint, and no mechanical heating
runs.
• When the zone temperature rises above the cooling setpoint, the primary air damper increases
the flow, and no mechanical heating runs.
• When the zone temperature falls below the heating setpoint, the system uses supplemental
heating first, then box heating. The damper remains at a minimum flow setpoint during the
heating period.
Note:
• One exception to the above staging procedure is if the ZEC510 controls hot water valves
and the
Control Application Type
is set to
Incremental
. The system assumes that there
is an incremental water valve and you can set
Dual Max Enable
to
Enable
. This option
can provide tighter control of air exiting the box.
• The box reheat and supplemental reheat are a box option. You have a cooling only box if
you do not choose either reheat or supplemental reheat.
Unoccupied mode
• When the zone temperature is between the unoccupied heating and cooling setpoints inside
of the bias, the primary air damper is at the minimum cfm, and no mechanical heating runs.
• When the zone temperature rises above the unoccupied cooling setpoint, the primary air
damper increases the cfm, and no mechanical heating runs.
• When the zone temperature falls below the unoccupied heating setpoint, the supplemental
heating coil is fully used before the reheat heat coil engages. The damper is at the minimum
cfm.
Unit enable
A network unit
Enable
signal controls the mode of the box. If you set the signal to
Disable
, all
outputs for that box are disabled.
Fan control (optional)
A parallel fan cycles on when a request for heating occurs. The fan remains off in all other cases.
Series fans run continuously in occupied mode. The fan moves from unoccupied mode to cycle on
mode when it receives a request for heating or cooling.
Occupancy lighting switch (optional)
• You can add an occupancy lighting switch to the box to temporarily set the VAV box to standby
when mode it does not detect occupancy. When the box detects occupancy, the zone switches
back to occupied mode.
• Standby mode uses standby heating and cooling setpoints that are slightly higher and
lower than the occupied cooling and heating setpoints, respectively. The VAV box also uses
unoccupied flow setpoints.
Verasys ZEC510 VAV Controllers Installation Guide
24
