Central heating losing pressure all the time

[MT Poole]

Every two weeks or so I have to go and top up the system because the hot taps are running cold. Boiler display is flashing 0.6 bar and I fill up to 1.3. I've had an engineer look inside the boiler and he can't see anything wrong. I've checked the pipes all over the house and cannot see any obvious leaks. Is it worth replacing the radiator valves? They aren't that old and it seems to be quite a lot to be losing all the time for it to be a small leak but I can't think what else it could be.

 

[fowlerboi]

Get a decent engineer to isolate the boiler and test. It will then be obvious if its the system or the boiler. From that point its fairly easy to figure out. If its the boiler it will likely be the Heat exchanger or the pressure relief, if its the heating system and you're not showing any water on ceilings then it will probably be under the ground floor somewhere (do the obvious checks and make sure you've not got green crusty lumps around the pipework you can see in the airing cupboard/boiler/radiators. It could possibly be a pressure relief that's separate from the boiler instead

 

[PSxxxxxx]

It's always the pipework you can't see that's the problem