I heard it was supposed to have been done last Wednesday morning, but the engineer di not turn up.
But that aside, i dont see the point. suppose a heating system has a problem with losing water, it could be the PRV valve which is on the boiler, or it could be a rad with a hole (or a million other things) but which do you put it in?
Also some one today posted a boiler quetion in appliances so a boiler forum has no chance.