The NIBE Low Pressure Switch (Part No. 418878) is a safety component used primarily in classic NIBE Fighter series ground-source heat pumps.

Technical Specifications

• Cut-Out Threshold: 1.5 Bar

• Function: Continuously monitors low-side refrigerant pressure. If pressure drops below 1.5 bar (due to a refrigerant leak, brine loop freezing, or heat exchanger issue), the switch opens to shut down the compressor and protect it from severe mechanical damage.

Key Model Compatibility

This part is widely used across classic NIBE ground-source heat pump models, including:

• Fighter 1115 (8.5kW, 10kW, 13kW)

• Fighter 1125 / 1225 (5kW to 17kW)

• Fighter 1130 / 1230 (6kW to 17kW)

• Fighter 1135 / 1235 (6kW to 17kW)

• Fighter 1140 / 1150 / 1250 / 1320

You typically need to replace or test this component if: 

1. The heat pump’s display shows a persistent Low Pressure Alarm / Defrost Fault even when refrigerant charge and brine/air flow are completely normal.

2. The internal microswitch has failed open, preventing the controller from starting the compressor.