For the last few months, I have had reduced/non-existent flow of hot water out of my taps: kitchen, bath and basin.
Water is hot when it [i]does[/i] come out, but often there's
- no water coming out...
- or there is a pathetic dribble...
- or there is a long lag (2 mins-20mins).
I live in a 6th floor flat in London, so I expect problems with water pressure every now and again (Thames Water leaks, high demand, etc.) but this is happening regularly - both at high demand times and low demand times (e.g. 3am) and I have additional pumps (in my flat) for the CH and HW.
Thames Water say pressure to building is average 2.2-2.4 bar.
Pressure valve gauge under kitchen sink is at over 1 bar (and has remained stable for last 2 years) but this does not accurately reflect the pressure coming out of the HW tap.
On opening hot water tap, if there is HW, I can hear the pump working, but not a peep when there is no water flowing.
Potterton Prima 40F boiler 'seems' OK as CH working fine.
I am tempted to treat it as an air-lock and follow the [url=http://www.diydoctor.org.uk/projects/curingairlock.htm]article[/url] but worried that if it's limescale build-up this will cause a problem.
The flat is 50 years old and looks ancient. Could it be that it's on its last legs or something more sinister?