Refrigerant Leak Sensor System:
- Sensor Purpose:
- UL requirement for units using A2L refrigerant
- Detect the leakage of the refrigerant
- Installed in Air Handler unit (for split units)
- Who manufactures the R-454B Leak Detection Sensor used:
- Danfoss
- The sensors self-calibrate
- The sensor auto resets
- Sensors are calibrated to trip at 15% Lower Flammable Limit (LFL)
- The factory-provided sensor is only set up to detect R-454B
Mitigation Action in the Event of a Leak:
When the system detects a leak, the following mitigation actions will be initiated until the refrigerant has not been detected for at least 5 minutes.
- Alarm Activation & Mitigation: When refrigerant concentration exceeds the threshold, the supply fan starts, and mitigation actions are invoked via Modbus interface (Address-50). Units only have one sensor.
- Continued Mitigation: Even after the refrigerant concentration falls below the threshold and the alarm resets, mitigation actions continue for an additional 5 minutes.
- Return to Normal Operation: After the 5-minute mitigation period, the system reverts to normal operation.
If the leak detection sensor has a fault, at the end of its life, or disconnected, the unit will initiate mitigation actions. Disconnecting the sensor may verify mitigation actions.
Location:
A.0 and B.0 Cabinets
D.0 Cabinets
Access D.0:
- Lock unit disconnect.
- Detach pipe, P-trap connected to condensate drain opening in the post.
- Remove the indoor refrigeration coil panel, indoor fan panel, and heat section panel(s), followed by the vertical post to which these were attached.
- The leak sensor is located just above and to the right of the drain pan outlet.
Connection Type:
- The leak detection sensor is a 6-pin plug: a 2-pin Modbus and a 2-pin contact.
Factory Installed wiring:
A2L Sensor & Failure Handling:
The A2L sensor is required for refrigerant detection. Symbio 700 detects sensor failures and implements mitigation actions for the duration of the failure. The system reverts to normal operation once all failure states are cleared.
- End-of-life indication or fault
- Sensor is unpowered
- Sensor wiring fault or misapplication
- Sensor disconnected
- Communication loss
Replacement:
- Replacement A2L sensors come programmed at Modbus address 50 by the supplier.
Alarms:
- Refrigerant Leak Sensor Communication Status Sensor A
- Diagnostic: Refrigerant Leak Sensor Failure Sensor A
- Diagnostic: Refrigerant Concentration Sensor A