I am banging my head against a brickwall.Went to a 24 ci that had hot water problems (low temp) on opening the boiler up noticed that no inhibitor had been originally used so dhw heat exchanger was sludged and 3 way valve actuator affected .Replaced the exchanger and the actuator and fitted missing flow restrictor (£10 for a plastic washer F*** Me) water a little hotter but still getting heat going through central heating flow. checked 3 way seats for debris they are clean and tried again same problem 3 way motor axle is thrusting as it should but still losing primary heat to central heating circuit (by pass is shut at boiler) Glowworm have suggested it must be the hydro block itself? has anyone any idea cost of hydro block £200 boiler is not under guarantee in its 2 yr because cost cutting landlord didn't get it serviced at 1yr old (boiler fitted cheap aswell comes around doesn't it!) HELP 
