I have a Vokera Linea 726 combination boiler which has worked okay for around 3 years. Recently I have found the hot water pressure to be very weak when more than one tap is running in the house and find it takes around 15 minutes to run a bath.

I have measured the flow rate to be around 4 litres per minute but this drops to around 1 litre per minute from one tap when 2 taps are running.

Temperature remians warm at both taps.

The boiler pressure has not dropped or changed and remains around 1-1.5 bar.

I have also checked for leaks in my system and although i found 2 radiators were leaking very slightly, I have repaired them and the problem remains.

I tried cleaning the inlet filler pipe (silver braided connection) which was mildly dirty but not overly bad and also tried running the system without the coloured filter washer which helped a lot however i do not wish to run the system without this filter.

I have considered switching to a higher flow coloured washer filter however I am loath to do this as the system worked fine until recently.

Can anyone suggest where my problem may be?

RK, September 2009

you have taken the fillter out and it has made a diffrance to that tells me there is something restriton the flow, I would be taking the domstic hot water heat exchange off and cleaning it out, then refitting it.
Not easy better off getting a heating eng in to do it

erj, September 2009

Forgot to say, it sometimes makes a loud bang when firing, usually when cold, and there can sometimes be a whirring noise which sounds like a pump or fan is struggling

RK, September 2009