AHU - Mixed Damper Operation
Testing Procedure
Pre-Conditions Check
Before testing is started, it must be verified that the AHU is running.
- Verify that device is “Occupied”.
- Verify fan is running by checking that duct pressure is more than 0.4psi [Pressure Min Threshold]
If any of these conditions are not met, STOP the workflow and ARCHIVE.
Setup Testing Conditions
In order to ensure that testing is accurate, outside air temperature must be high enough to prevent freezing of the damper if it were to close.
- Verify that outside temperature is greater than 35°F [OAT Full Ventilation].
Test Damper Operation
Open Mixed Damper
- Command mixed damper to “OPEN”
- Pass if mixed air achieves a temperature greater than 5△°F [Full Mix - Delta] below return temperature
Close Mixed Damper
- Command mixed damper to “CLOSED”
- Pass if if mixed air achieves a temperature less than 5△°F [Ventilation - Delta] above outside temperature
Tuning Parameters
| Display | Hint |
|---|
| Pressure Min Threshold [0.4psi] | How much should the duct pressure be minimally. |
| OAT Full Ventilation [35°F] | The OAT minimum setpoint to allow full ventilation. |
| Full Mix - Delta [5△°F] | The temperature threshold tolerance for fully open mixed damper. Delta below RAT for fully open mixed damper. |
| Ventilation - Delta [5△°F] | The temperature threshold tolerance for fully open mixed damper. Delta below RAT for fully open mixed damper. |
| Reaction Time [300sec] | How long to wait for the actuators to fully do their job. |
| Stabilization Time [60sec] | How long to wait for the system to come to stability after we have given it an actuator command and the conditions have been fullfiled. |
| Measure After [60sec] | How long to wait in seconds to start checking the feedback readings.
|
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