yes I do have to top up occasionally, if the boiler is off, the pressure remains normal, however it rises above the top limit when heating is on. Thanks for responding.
My sime friendly format 80 e has 2 problems. It fails to ignite when it comes back on automatically, this I believe requires a new pcb, and when heating is on the 'overflow' constantly drips.The pressure gauge shows normal but is high when heating is on. Can anyone help please. :(