Went to a job to fix a leak on a toilet today and the house was empty. The airing cupboard door was open so as I've not long qualified for unvented I couldn't resist looking at the unvented cylinder configuration. (I'm sad like that). I. The D1 pipe from the T&P relief valve was ok, piped to a tundish but the expansion relief valve (incorporated underneath the combination valve) was piped straight outside without an air break. In my book this is wrong. Also the D2 pipe is grossly undersized as it travels approx 10 metres with god knows how many elbows. Also the two pipes terminate 400mm above ground level straight onto the path outside with no guard. Am I correct in my observations that all three points are contravening the building regs? I haven't worked on the system but is there an obligation to report it to building control/HSE?