|Overview
A temporary Override is an option in the setting screen of a 75F CCU, where all the input and output parameters for system and zone level profiles paired are listed.
There is an indication for the configured (with a control signal name) and non-configured (with a "not used"), and the not enabled (with a "not enabled") points under the parameter names. The points include the input and output points and the points that can be overridden. The user can monitor these points and can override these points.
The changes to the system and zone-level parameters override the algorithmic values applied to the system and zone-level profiles. The changes are in effect only till the time the user stays on temporary override which is limited to one hour.
Once the user navigates away from the temporary override screen, or the time limit of one hour expires the changes are reverted to the original values as per the algorithm, hence the name temporary override.
|Accessing Temporary Override Screen
To access the temporary override screen in the CCU.
Procedure
From the CCU zones page.
- Click the settings
icon.
The floor layout screen is displayed.
- Click Settings.
The setting screen is displayed.
- Click the Temporary Override
icon.
The temporary override screen is displayed.
Caution: If changes to the system and zone-level equipment are not handled correctly, it might cause damage to building equipment.
The following table explain the fields available in the screen.
| Field | Description |
| I/O Parameters | You can see the input and output parameters configured for the system and zone level profiles under this field. |
| Input Value | You can see the input values along with unit for all the Analog-in points. |
| Calculated Output Value | You can see the output value/state which is currently written to the analog-out, relay and thermistor points. |
| Override |
You can use this option to override the respective input and output values that are populated in the Input Value and the Calculated output value fields. Example 1: For a DAB fully modulating AHU, when Analog-Out 1 is mapped to Cooling, if the value according to algorithm is 20%, you can override it to a 100%, and the system starts cooling at 100%. Example 2: For an analog-in mapped to temperature sensor values ranging from 0-10V, and the current value is 2V, You can override it to 5V, so the algorithm considers the overridden value and changes accordingly. |
| Time Limit |
You can see the time left, out of the one hour time limit for which you can stay on the temporary override screen and modify the values. You can use the refresh icon in the time left window to reset the time limit, if you wish to stay longer on the screen, and continue to modify the values, when clicked the time left resets to one hour. |
- modify the parameters according to the requirements.
As we can observe in the above images, the values for Thermistor 1 and Thermistor 2 have changed from 2784.0 Ohm to 1000.0 Ohm & 4900.0 Ohm to 2700.0 Ohm respectively. Once the values are changed, the change is observed within a short period.
Note: The changes take effect in the devices, portals, and apps, for the algorithm to act upon and provide the required conditioning.
|Examples
| Parameter Modified | Effect observed in | Effect in Algorithm | Change in Conditioning |
| Analog In (Temperature sensor) | Incoming sensed value is reflected in the module-level devices (SN/HN/HS) & Portals for the algorithm to act upon and start the required conditioning. | The algorithm starts the required heating/cooling conditioning based on the sensed parameter | Increase or decrease in Heating/cooling |
| Analog Out (Damper positions) | Outgoing modulating damper position % is reflected in the module level devices (SN/HN/HS), and portal for the damper to increase or decrease its opening. | The algorithm takes up the new modified value and directs the damper actuator to increase or decrease the damper opening. | Increase or decrease in Heating/cooling |
| Thermistor (Airflow temperature sensor) | Incoming sensed value for airflow reflecting in the module level devices (SN/HN/HS) and portals, for the algorithm to act upon and start the required conditioning. | The algorithm takes up the new modified value of airflow sensed, and directs the controls | |
| Relay | Outgoing staged fan speed control is reflected in the module-level devices (SN/HN/HS) and portals, to increase or decrease the fan speed | The algorithm takes up the new modified value of the staged fan speed value and actuates the same | Increase or decrease in Heating/cooling |
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