Temperature Control; Heating Mode; Cooling Mode - ABB FBVi-2U4-4T User Manual

TEMPERATURE CONTROL

The FBVI-2U4-4T continuously compares the zone temperature with the active setpoints. Zone
temperature is detected from UI1 or a CBT-Stat.
Heating demand and cooling demand calculations are constantly updated. These calculations are
expressed as 0 ... 100% heating needed and 0
Default temperature setpoints are 71°F/75°F for the occupied mode heating/cooling and 65°F/85°F for
the unoccupied mode heating/cooling.

HEATING MODE

In the heating mode, stages of heat are energized, and/or valve positions are increased, as the heating
demand increases. The primary supply air Flowrate is set to the current primary air heating flow setpoint.
If the unit includes a fan, see the Fan Control section in Section 3.
In an OCCUPANCY state, on a fall in zone temperature below the
demand will rise from 0-100%. If heat is available, the stages of heat will be enabled. The damper will
modulate to maintain the
minHeatFlowStpt (A230)
zone temperature above the
available, the stages of heat will be disabled.
The occHeatStpt (A124)
will be reflected by the
If the discharge air temperature is above the
heat will be locked out until it falls below 120F (49C)
Note: While in warmup mode or hot air is present, accessory heat will not be commanded on.
In an UNOCCUPANCY state, on a fall in zone temperature below the
demand will rise from 0-100%. If heat is available, the stages of heat will be enabled, and the unit will be
in Setback Mode. The damper will modulate to maintain the
minHeatFlowStpt (A230)
zone temperature above the
available, the stages of heat will be disabled.

COOLING MODE

In the cooling mode, the primary air Flowrate setpoint is modulated toward maximum as the cooling
demand increases. If the unit includes a fan, see the Fan Control section in Section 3.
In an OCCUPANCY state, on a rise in zone temperature above the
demand will rise from 0-100%. The damper will modulate to maintain the
activeFlowSetpoint(A236),
a fall in zone temperature below the
The occCoolStpt (A123)
will be reflected by the
In an UNOCCUPANCY state, on a rise in zone temperature above the
demand will rise from 0-100%. The unit will be in Setup Mode. The damper will modulate to maintain the
activeAirflow (A250),
in zone temperature below the
Note: If the user tries to set the cooling setpoint
occHeatStpt (A124), the heating setpoint will be automatically lowered. If the user tries to set the
heating setpoint occHeatStpt (A124)
setpoint will not change.
©ABB 2021 All Rights Reserved.
Subject to change without notice
WWW.CYLON.COM
... 100% cooling needed.
activeAirflow (A250) to the
to maxHeatFlowStpt (A229),
occHeatStpt (A124),
setpoint can be affected by shed or standby modes. The active heating setpoint
activeHeatStpt (A188).
highDuctTempLockout setpoint (A34)
to maxHeatFlowStpt (A229),
unoccHeatStpt (A126),
and it will reset from
occCoolStpt (A123),
setpoint can be affected by shed or standby modes. The active heating setpoint
activeCoolStpt (A187).
and it will reset from minCoolFlowStpt (A227)
unoccCoolStpt (A125),
occCoolStpt (A123)
higher than the cooling setpoint
FBVi-2U4-4T |
occHeatStpt (A124),
activeFlowSetpoint(A236),
depending on the VAV configuration. On a rise in
the heating demand will fall from 100%-0. If heat is
unoccHeatStpt (A126),
activeAirflow (A250),
depending on the VAV configuration. On a rise in
the heating demand will fall from 100%-0. If heat is
occCoolStpt (A123),
activeAirflow (A250)
minCoolFlowStpt (A227) to
the cooling demand will fall from 100%-0.
unoccCoolStpt (A125),
to maxCoolFlowStpt (A228).
the cooling demand will fall from 100%-0.
lower than the heating setpoint
occCoolStpt
Control Sequence
the heating
and it will reset from
of 180F (82C ) the
the heating
and it will reset from
the cooling
to the
maxCoolFlowStpt (A228). On
the cooling
On a fall
(A123), the heating
84