f Oxygen Ingress - Interim Report 2

There was an event at the Redcar EcoHouse, where after the isolation of the hydrogen pipework for 27 days, over the Christmas break 2023/2024, and shortly after initiation of the flame in a hydrogen gas fire appliance, a minor ignition event occurred. Visual investigation led to a discovery that the gas meter was damaged.
Air ingress into the isolated hydrogen pipework (causing a flammable mixture in this pipework) followed by the flame propagation from the ignition system of the hydrogen gas fire, were considered to be the most likely reasons for the aforementioned event.
The aim of the work presented in this report was to complement the work undertaken by Steer Energy and to:
• investigate the possibility of the above phenomena to occur in domestic hydrogen installations with main focus on hydrogen appliance design
• to conclude whether there are plausible explanations of the event observed at the Redcar EcoHouse
• to propose possible mitigations which are likely to prevent similar events in the future.
This report was submitted to HSE for their assessment of the safety evidence for 100% hydrogen heating, which can be found at Hydrogen heating: HSE assessment of the safety evidence - GOV.UK.
Queries should be directed to DESNZ: https://www.gov.uk/guidance/contact-desnz.