my caravan has a worcester combi boiler, it was only connected up yesterday & the water pressure gauge was set at between 1 & 1.5. i have not used the heating, but when i use any hot water the gauge rises to between 3&4 & the overflow runs/drips outside. what is likely to be causing this & is it a costly job to resolve. we have bled the radiators & the pressure dropped but as soon as we use the hot water again the gauge goes up quickly

caz, July 2011

if it's only just been installed my guess is that the expansion vessel hasn't been connected, as they usually aren't pre connected on worcesters get the installer back

Evro, July 2011

The pressure vessel needs recharging or it needs replacing

jeff stockdale plumbing & heating FY5 5AE, July 2011

heat exchanger scaled up?

A1, July 2011