Chris,
I'm very sinical about the non steamers being sold today. Yes there are a few flats, but most boilers allow a lot of flue diversion inside the building which would make up for difficulties with positioning. No longer can we expect to always hang boiler on wall and get flue out of side or back straight through wall all nice and cosy. Bends extensions and vertical flue kits are coming home.
I was in pts other week, buildery looking bloke was asking for a heat pack, Bob behind counter said condensing or non condesing? "non condensing", off he went with it. I bit my tongue. After he'd gone I said to Bob. How can he fit that? Bob shriugged his shoulders, "we're still selling loads of them, a builder was in here last week and bought 10 of them."
I once went to an emergency with unvented kit for an insurance company (nearest guy to Pontefract with unvented cet. who ansered the phone that night)
New build, with unvented kit and sealed system kit for regular boiler, and pump in loft cupboard. Customer who was first purchaser from builder, had been told by the builder "you don't need to worry abouyt what's in there".
Pressure of main system went low, but because it only relied on OH stat to know it didn't cut out becaue boiler was 3 floors down. Pump however right up in that room was running dry and making the noise which allerted the emergency call to the insurance company. However the unvented kit was a little dubious although not strictly wrong, neither it nor the boiler had Benchmark's filled in.
Isn't this happening where you are?