Baxi 105 HE pressure drop

[jacobball]

Hi Our baxi 105he combi has a problem. The pressure has dropped to under 0.5 bar in about a week. we've only used hot water, and when it dropped the boiler didn't fire, until topped up again. The pressure rose to 3 bar when heating was tested last week and the expansion vessel was re-charged and all was good, the pressure increased a little but not to 3 bar.

Is this possibly a small leak somewhere? Any ideas where to look?

Thanks for your help

 

[MANDATE]

If the pressure has been to 3 bar it has most likely discharged some water out of the pressure relief valve causing the pressure to drop.
It is also likely the PRV has not sealed properly and left you with a small leak.