When my combi boiler starts from cold it is extreamly noisy and the pressure gauge flickers over about 0.5 bar once the water is up to temperature it runs quietly it is not the prv any ideas please.
0.5 water pressure is to LOW, add more water to the system via the filler loop till up to 1.5 bar cold,
with the heating on system should rise and sit at around the 2 bar mark quite happily all day long
