YORK YK — Leaving condenser liquid - High temperature

The OptiView Touchscreen Control Center shows Leaving condenser liquid - High temperature. The manual lists this message among the cycling faults, and its description is given with the Heat Pump Screen in the fault messages list.

The leaving condenser liquid temperature has increased to the programmed heating shutdown temperature setpoint. This is a cycling shutdown, not a lockout, and it exists only when heat pump duty is enabled and the heat pump operational setpoint is set to heating mode. There is also a transition rule: when the heating setpoint is decreased, the shutdown threshold becomes 125°F (51.7°C) for the next 10 min; after 10 min have elapsed, the shutdown threshold becomes the programmed setpoint value.

• The leaving condenser liquid temperature rose to the programmed heating shutdown temperature setpoint.
• The shutdown can only occur when heat pump duty is enabled, the unit is operating in heating mode and the heat pump operational setpoint is set to heating mode — outside heating mode this message does not apply.
• Shortly after the heating setpoint has been decreased, the shutdown threshold is held at 125°F (51.7°C) for 10 min before it follows the new programmed setpoint value, so a shutdown in that window is judged against the temporary threshold.

1. Confirm the shutdown applies to the current mode: it is only applicable when heat pump duty is enabled, the unit is operating in heating mode and the heat pump operational setpoint is set to heating mode (see the Heat Pump Screen).
2. Read the Heating Shutdown Temperature on the control center — it displays the leaving condenser liquid temperature at which the heat pump shuts down on this cycling shutdown in heating mode.
3. Read the Effective Heating Shutdown Offset — the present offset below the selected heating setpoint at which the shutdown occurs — and compare it with the actual leaving condenser liquid temperature.
4. Check the Local Heating Setpoint (programmable from 65.0°F to 122.0°F, default 95.0°F) together with the Heating Shutdown Offset (1 to 59°F below the setpoint, default 1, to a maximum of 125°F) to see which threshold was programmed.
5. If the heating setpoint was just decreased, remember the shutdown threshold becomes 125°F (51.7°C) for the next 10 min and only then becomes the programmed setpoint value.

• Local Heating Setpoint — the leaving condenser liquid temperature to be maintained in heating mode; programmable range 65.0°F to 122.0°F, default 95.0°F. A remote device can provide an analog signal that changes the setpoint, and an SC-EQ/SC-Connect in BAS Remote mode can set it through serial communications.
• Heating Shutdown Offset — defines the shutdown point as an offset below the selected heating setpoint; programmable over 1 to 59°F (default 1), to a maximum of 125°F. When the heating setpoint is decreased, this shutdown threshold is ramped to the new setpoint at the rate of 0.1/s to eliminate nuisance shutdowns.
• Heating Restart Offset — defines the restart point as an offset above the selected heating setpoint; programmable over 0 to 67°F (default 0), to a minimum of 55°F. It can be used to reduce chiller cycling by delaying the heat pump restart until the heating load has increased.
• Displayed values — Heating Shutdown Temperature, Heating Restart Temperature, Effective Heating Shutdown Offset and Effective Heating Restart Offset show the resulting absolute temperatures and the present offsets.

No manual reset is described — this is a cycling shutdown with automatic restart. The heat pump automatically restarts when the temperature decreases to the programmed heating restart temperature setpoint. That restart point is the selected heating setpoint plus the Heating Restart Offset (0 to 67°F, default 0), but not below 55°F; increasing the offset delays the restart until the heating load has increased.