Leak testing with oxygen caused heat pump blast
10th September 2025
POLAND: Authorities in Opole have concluded that the heat pump explosion in Chrząstowice that killed two people last year was caused by using oxygen to carry out pressure tests.
The heat pump explosion on August 20, 2024, killed two people, a 30-year-old engineer, who was servicing the unit, and the 45-year-old property owner. They were said to have suffered multiple injuries to the chest, head, arms and legs. A third individual was injured and taken to hospital.
The Nowa Trybuna Opolska website quotes the district prosecutor’s office as saying: “According to our findings, the explosion was caused by the use of technical oxygen to check the system for leaks. It mixed with oil vapours from the pump’s external unit, causing a violent ignition and explosion, which ultimately ruptured the structural elements of the device, which struck the injured parties.”
Pressure testing a DX system with oxygen instead of a non-reactive gas like nitrogen is extremely dangerous. The oxygen can react violently with oils and grease present in the system, leading to potential explosions.
The attorney for one of the victims has filed an appeal against the decision.
The explosion was said to have torn the heat pump apart with metal fragments damaging the walls and roofs of neighbouring houses. A fragment of the casing was found in the parking lot of a store 300m away. The air-to-water unit was using R410A.
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