heatline s30 combi gas boiler?

hi
i have a heat line boiler s30 when the heating is on the pressure rises slowly to 3.5 bar in the red i darained some of the water from the system and now when cold its at 1.3bar and rises to 2.8 when the heating is on it would take about 1.5hrs of the heating on to rise to 2.8bar also the leds witha rad pic and a spanner a house and the bar light are on the whole time on the diagnostic leds and sometimes a light with an arrow pioting up comes on i have no manual on the boiler, any help please would be great