Combi boiler at 1.2 when operational is that normal?

Wanderer2010

I have a Logic Combi Boiler and at rest it's normally about 0.5 bar and when it's heating the rads or shower it's typically 1.2 bar maybe 1.5 bars when left on more than 2 hours. I had to add water from the filling loop about 3 months back as it was showing the F1 error over and over and barely climbing to 1 when operating. That raised the pressure right away.

But according to different forums and engineers opinions apparently the pressure should be 1.6 or 1.8 when heating and 1.0 at rest. There are no leaks in any of the radiators in the house and it's not like there's a huge difference between 1.2 and 1.6. Do you think this difference is enough to call someone in? I'm afraid they might fleece me by saying there's a hundred things wrong with it as I don't know a huge amount about gas boilers. I get it serviced each year but last time was March 2023.

10-10-20

Hi ya! I'm not a plumber but with a rise like that I'd be suspecting a possible issue with an expansion vessel. Maybe somebody else on here might know better.