i have an ariston system boiler with a small leak from the pressure relief valve, which over a few days allows the pressure to drop and thus the boiler locks out, then i have to top it back up has anyone got any ideas?
Can sometimes be re-pressurised to 1.0bar using a foot pump or similar.
Drain boiler so there's no pressure - lock open the pressure relief valve, Then pump to 1.0bar and refill system.
See if there's air at the valve on the expansion vessel. The valve looks like a one off a car or bike, If there's air then re-pressurising may work, if there's water then a new expansion vessel is required.