@quixoticgeek Having just read through a Hydrogen Safety data sheet, I'd be very worried about (1) the pipe work, are they replacing all the pipe work with Hydrogen tested pipe, Hydrogen dissolves in many metals and in addition to leaking out, may have adverse effects on them, such as hydrogen embrittlement (2) Hydrogen gas leaking into external air may spontaneously ignite. Hydrogen fire, while being extremely hot, is almost invisible, and thus can lead to accidental burns