Please help. ideal mini C screeching + HW lock-out

[amano]

Hi,

I have an ideal mini C combination boiler. The central heating seems to work fine, however, switching on a hot tap results in an awful (and very loud) screeching noise from the boiler and then it locks out (the lock-out light comes on, bolier shuts down). Oh, I also noticed that the temperature gauge usually rises from ~60 to 70/80 when this happens.

Turning on a hot tap without the central heating running often produces the same result as above, but sometimes the bolier just locks out straight away (no noise or temp increase).

My boiler only started doing this yesterday. What is it's problem? Do I need an engineer?

 

[Agile]

The plate heat exchanger is blocked because the installer failed to clean the system.

Or alternatively the filling loop has been left open and caused the system to get sludged up.

We charge £136 to clean out the boiler but advise that that is a quick fix and ideally the system should be chemically cleaned at £180 or power flushed at about £320.

Tony Glazier