Combis Fitted Where a Cylinder Used to Be
A large share of Liversedge homes have been through the same change at some point: the hot water cylinder removed and a combi fitted to feed the taps directly. Done properly, that is a sensible swap. What it also means is that a newer boiler has often been connected to pipework that was already decades old, and whatever had built up inside that pipework went straight through the new boiler's heat exchanger.
Soft West Yorkshire water corrodes the inside of steel radiators rather than leaving limescale, and the result is a black magnetite sludge. On a converted system it tends to show up as a boiler that locks out, a pump that labours and then seizes, or a combi that overheats and cuts out halfway through a shower. The breakdown is real and needs fixing now, but the cause sits further back in the system than the part that failed.
So the emergency visit does two separate jobs. The failed part is found and replaced, with the price agreed before anything is fitted. And if sludge is what took it out, you are told so plainly, along with what would stop it happening again — a system flush and a magnetic filter. That is a decision for another day, not something quietly added to the bill while the house is cold.