YORK YK — Warning - Loss of subcooler liquid seal

The control center shows Warning - Loss of subcooler liquid seal. The same warning is printed in other YK documents as Warning - Loss of Subcooler Liquid Seal and WARNING - LOSS OF SUBCOOLER LIQUID SEAL. It belongs to the Warning messages group of the OptiView Touchscreen Control Center and is described there as a manual reset warning.

The warning indicates that the liquid seal in the subcooler has been lost. The control detects the loss through the calculated subcooler effectiveness and through the drop leg temperature, which the manuals compare with the return condenser liquid temperature (ECLT). The trigger conditions are evaluated only after the chiller has been running for 30 minutes or more.

• The chiller has been running for 30 minutes or more, and the Drop Leg Temperature has stayed below the Return Condenser Liquid Temperature continuously for two minutes.
• After at least 30 minutes of running, the calculated Subcooler Effectiveness is below the Subcooler Effectiveness Low value (0.4) or above the Subcooler Effectiveness High value (1.5) continuously for two minutes.
• With running time above 30 minutes: subcooler effectiveness below the low threshold together with input FLA greater than 40%; or subcooler effectiveness above the high threshold, the drop leg temperature below ECLT minus 0.5°F, and input FLA greater than 40%.

1. Confirm the chiller running time — the trigger conditions apply only after 30 minutes or more of running.
2. Read the input FLA: both trigger paths in the warning-message table require input FLA greater than 40%.
3. Check the calculated subcooler effectiveness against the low value 0.4 and the high value 1.5; the warning trips when it stays outside this band continuously for two minutes.
4. Compare the drop leg temperature with the return condenser liquid temperature (ECLT); one trigger path needs the drop leg below ECLT minus 0.5°F.

• Subcooler Effectiveness Low value: 0.4
• Subcooler Effectiveness High value: 1.5
• Subcooler Effectiveness = (Cond Sat Temp − Drop Leg Ref Temp) / (Cond Sat Temp − Entering Cond Liq Temp)
• Running time before the conditions are evaluated: 30 minutes or more
• Input FLA level in both trigger paths: greater than 40%
• Drop leg temperature trigger: below ECLT minus 0.5°F
• Duration a trigger condition must persist: continuously for two minutes

The warning needs a manual reset and can be cleared once the warning conditions are no longer in effect. The manual's clearing instruction: To clear message press the Clear button on the System Details Screen. When the warning is reset, the message Loss of Subcooler Liquid Seal Warning Reset is added to the Security Log.