My combi boiler is losing water pressure.(Ferroli). Under normal operation and with the radiator temperature on snowflake the pressure increases to about 2.5 bar and only needs topping up every now and again.If I turn up the thermostat the pressure increases and a relief valve(I think) discharges excess pressure outside onto the floor.This continues until the boiler shuts down on low water pressure.
Can anyone offer any suggestions as to what is wrong?I will eventually get a heating engineer to look at it but this could take time as they never turn up to your house when you ask them.