I have a worcester bosch highflow 400 combi boiler, about 14 years old. The hot water cuts in and out when the central heating is put on. I had the same problem last year and the engineer showed me how to increase the pressure, as that was the problem last year, I think it should be on 2, it is currently on 1. I do not remember how to do that (being a bit stupid!), can anyone tell me what to do?

chicklpea, November 2008

There will be a filler loop from the mains cold water into the closed CH system and a 1-way valve. This uses mains pressure to pressurise the CH system.

1-bar is good when cold as this will increase to 2.5bar approx when hot & circulating.

If the CH pressure drops to zero, it will cut out the heating.

Simon, January 2009

I'm not really sure myself as i think i might have to do the same thing, i think its something to do with the filler loop, i dont even know where its located. I wish i did :(

Kaiser, December 2008