I have a slow running hot bath mixer tap in a ground floor flat using a combi boiler (sealed system) which I am having difficulty finding the problem..
Water pressure is OK (adequate) to the bathroom wash basin and kitchen. Cold pressure is good to the entire flat.
I've had a couple plumbers round. 1st one gas engineer said boiler looked OK and was a result of the taps and poor mains pressure (neither covered under the insurance policy)
Got a 2nd plumber to come round who removed the taps, could not see anything wrong with the taps.. suggested possible problem with pressure between boiler and tap (maybe fur in pipe) and recommended a gas plumber?!
Not sure I believe there is problem with mains pressure as the cold water is fine.. Taps i think are fine as the cold mixer is good.
I have some tenants in the flat at the moment so unable to check things myself but if anyone has a clue to what it might it would be really helpful.