Mixed Air Damper (Modulating); Mixed Air Damper (2-Position) - United Technologies Carrier Unit Vent Open Integration Manual

Communications wiring

Mixed air damper (Modulating)

The Unit Vent operates a mixed air damper to maintain the desired cooling setpoint without mechanical cooling,
while also providing the required ventilation. The modulating mixed air damper is controlled by the PI
(Proportional-integral) cooling algorithm and integrated with mechanical cooling while also maintaining a minimum
OA intake if the optional CO
The desired Damper Setpoint is calculated by the controller when cooling is required. The Damper Setpoint
Override Value provides the capability to maintain a user-defined fixed supply air temperature when cooling is
required and available. It will override the PI temperature control algorithm when the Damper Setpoint Override
Value is not equal to 0 (and must be greater than 45°F (7.2°C). The Damper Setpoint is compared to the actual
supply air temperature and used to determine the Mixed Air Damper position.
The following conditions must be true in order for the modulating damper (economizer) algorithm to run:

Damper Type is Modulating

Space temperature reading is valid

Supply Fan must be on and not in Alarm

OAT is valid

Heat mode is not active

Fire/Smoke Detector (FSD) is Normal

OAT is less than Damper Lockout Temperature limit

OAT is less than RAT/SPT sensor

If occupied, the SPT is greater than the Occupied Cooling setpoint

If unoccupied, the SPT is greater than the Unoccupied Cooling setpoint
If all the above conditions are met, the mixed air damper will operate as an economizer as required, otherwise it
will be disabled and maintain either a closed or minimum damper position.
The configuration screens contain the Min Cooling SAT and Damper Lockout parameter based on outdoor air
temperature (OAT). Both can be adjusted to meet various specifications.

Mixed air damper (2-position)

The control can operate a 2-position (0-10 Vdc or 2-10 Vdc) type minimum outdoor air damper to maintain the
desired ventilation during occupied periods. The damper output provides a 10 Vdc signal when the control is
occupied or in an occupancy override mode. When the control is unoccupied or the fan is off, the damper output
will go to 0 Vdc. To control the maximum amount of outdoor air entering the unit, a mechanical actuator stop must
be set.
The following conditions must be true in order for the 2-position damper algorithm to run:

Damper Type is 2-Pos

Supply Fan must be on and not in alarm

The unit is in an occupied mode
Unit Ventilator
Integration Guide
sensor is available. See Indoor Air Quality (page 23) for additional information.
2
22
CARRIER CORPORATION ©2019
All rights reserved