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VAV MODULATING HOT WATER REHEAT VARIABLE SPEED FAN
TEMPERATURE CONTROL
When the zone temperature is greater than the cooling temperature setpoint, the controller will enter
the cooling mode. The primary airflow rate will be varied between its
maximum Flowrate setpoint
temperature setpoint. Once the zone temperature falls below the cooling temperature setpoint, it will
exit the cooling mode.
When the zone temperature is between the cooling and heating temperature setpoints, it will be in
Deadband or Vent Mode. The controller will maintain the
If the
activeAirflow (A250)
In heating mode, the controller will maintain the
When the zone temperature falls below the heating setpoint, the controller will enter the heating mode.
•
If no discharge air temperature sensor is configured:
As heating demand rises from 0-100%, the stages of heat shall be enabled to maintain
o
zone temperature setpoints.
As heading demand rises from 51%-100%, the fan speed setpoint shall reset from
o
minFanSpeed (A237)
•
If discharge air temperature sensor is configured (this meets ASHRAE Standards):
As heating demand rises from 0-50%, the discharge air temperature shall be reset
o
upwards, to a maximum of 20 deg above zone temperature. The stages of heat shall be
enabled to maintain the discharge air temperature setpoint.
As the discharge air heating demand rises from 51-100%, the fan speed setpoint shall reset
o
from the
The duct coil shall control the VAV discharge air temperature to the setpoint. The duct coil
o
shall not directly control zone temperature.
Typically, the modulating heating valve may be controlled by either
state control mode where
additional options available such as having
second stage modulating heat.
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maxCoolFlowStpt (A228)
is below the
minHeatFlowStpt (A230),
minHeatFlowStpt (A230).
to
maxFanSpeed (A238).
minFanSpeed (A237)
to the
drives the hot water valve open and
DO-09
AO-14
FBVi-2U4-4T |
minCoolFlowStpt (A227),
as required to maintain the zone at the cooling
minCoolFlowStpt (A227).
the heat will be disabled.
maxFanSpeed (A238).
or
AO-14
drives it closed. There are
DO-10
as the first stage modulating heat and AO 15 as the
FBVI-2U4-4T Contr
and its
and
in a tri-
DO-09
DO-10
78
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