YORK YK — Isolation valves - Not opened

The panel shows Isolation valves - Not opened; the control documentation also prints it as Isolation Valves - Not Opened. It appears as a safety fault of the Isolation Valves option.

This is a safety fault of the Isolation Valves option. The control has energized the Isolation Valves Open Output — the isolation open output relay on LTC I/O TB17 — for more than 40 seconds, but the Isolation Valves Opened Feedback has not come back: the isolation valve opened digital input on the LTC I/O board at TB19-3,4 stays low. In plain terms, the panel has told the valves to open and cannot confirm that they did. The fault is set once this mismatch has existed for 3 continuous seconds.

• Isolation valves is enabled on the setup screen — the fault logic applies only when the option is enabled.
• The Isolation Valves Open Output (the isolation open output relay on LTC I/O TB17) has been energized for more than 40 seconds.
• The Isolation Valves Opened Feedback is not energized — the isolation valve opened digital input on the LTC I/O board at TB19-3,4 remains low.

1. Confirm on the setup screen whether isolation valves is enabled; the fault only applies when the option is enabled.
2. Open the Status Report and look under the Condenser heading: with the option enabled it shows the state of the Isolation Valves as Closed, Opening, Opened or Closing.
3. Check the isolation open output relay on LTC I/O TB17 and whether it is energized.
4. Check the isolation valve opened digital input on the LTC I/O board at TB19-3,4 — the fault means this input is staying low while the output is energized.

• Setup screen: isolation valves enabled — the fault is active only with the option enabled.
• 40 seconds: how long the Isolation Valves Open Output may stay energized without the Opened Feedback returning.
• 3 continuous seconds: how long the mismatch between output and feedback must persist before the safety fault is set.

The fault does not release while the machine is running. The manual gives the release as: The fault is released when the chiller is not running and the Clear button is pressed next to the listed event on the Systems Details Screen. The control documentation adds the panel-side description: once the Compressor is in the stopped state, placing the Compressor switch into the stop position releases the safety fault.