boilers

[Lucysdad]

my combi boiler keeps going over 3 bar on the pressure gauge and water is leaking from the over flow, why is this????

[Mortartube]

Are the fill taps that you top up the system with, fully turned off?

[xx marti xx]

sounds like the water top up from your mains water to your heating side has been left cracked open or the valve is leaking.

[gasman]

As mentioned above the filling loop may be letting water into the system and need turning off properly and it should be dissconected any ways ( water regulations ).
Or the expansion vessle has failed and needs replacing. Then again you may just have too much pressure in the system to start with, It should be set to approx 1bar when the system is cold.