Communications wiring
Unit Ventilator
CARRIER CORPORATION ©2019
Integration Guide
All rights reserved
18
System Occupancy
Uses the network to obtain an occupancy status value from another controller, which is read over the network
and used by this controller.
Occupancy Schedules
MUST be set to
Disable
to use this function.
NOTE
Scheduling can only be controlled from one source.
Supply fan
You can configure the indoor fan to operate in any 1 of 3
Fan Modes
:
Auto
- runs intermittently during both occupied and unoccupied periods
Continuous
(default) - runs continuously during occupied periods and intermittently during unoccupied
periods
Always on
- runs continuously regardless of occupancy
In the
Continuous
mode, the fan is turned on when one of the following is true:
It is in occupied mode, as determined by its occupancy status
There is a demand for cooling or heating in the unoccupied mode
There is a call for ventilation (IAQ override - optional)
When power is reapplied after a power outage, or when transitioning from unoccupied to occupied, you can
configure a delay of 5 - 600 (default 60) seconds before starting the fan. Configure as follows:
Fan On Delay
defines the delay time (0 - 30 seconds, default 30) before the fan begins to operate after
heating or cooling is started and is automatically overridden if electric heat or DX cooling are active.
Fan Off Delay
defines the delay time (0 - 180 seconds, default 120) the fan continues to operate after
heating or cooling stops.
The fan runs as long as cooling, heating, economizer operation, or DCV is active. If the space temperature failure
alarm, condensate overflow alarm, or the test mode is active, the fan shuts down immediately, regardless of
occupancy state or demand.
Automatic Fan Speed Control
- The Unit Vent controls up to 3 fan speeds using a Fan Interface board or field-
installed relays. The fan motor operates at the lowest speed possible to provide quiet and efficient fan operation
with the best latent capability during cooling. The motor increases speed if additional cooling or heating (except
for electric heating) is required to reach the desired space temperature setpoint. The motor's speed increases as
the space temperature rises above the cooling setpoint or falls below the heating setpoint. The amount of space
temperature increase above or below the setpoint that is required to increase the fan speed is configurable. Also,
the fan speed increases as the
Supply Air Temperature
approaches the configured minimum or maximum SAT
limits if DX cooling or electric heat is active.
Configuring Automatic Fan Speed setpoints
– When configured for more than 1 speed, the fan speed selection is
based on Space Temperature compared to the Effective Setpoints. For example, if configured for a 3-speed fan,
the fan will go to Medium speed when the Space Temp exceeds the Cool 1/ Heat 1 level. The setpoint graph
represents this as the yellow and light blue areas. The fan increases to High speed when the Space Temp exceeds
Cool 2/ Heat 2 level. These are represented by the orange and dark blue areas. Speed is reduced when the Space
Temp passes the same threshold, but includes a non-adjustable Hysteresis (differential) of 0.5 °F (.27 °C) for
both heating and cooling modes. All color bands (yellow, orange, light blue and dark blue) MUST be set to more
than 0.5 °F (.27 °C).
