overheating boiler

[patrickk]

i have a baxi solo boiler on pressurised system that is overheating when the heating is on, ie this doesn't happen when working in hot water only mode. after some time i can reset the boiler, but sooner or later the overheat problem recurs.
Potterton have called twice and changed the heat sensor, the pump and the p.c.b. and i have bled the radiators and no air is escaping.
can anyone help with a solution

 

[dan the man]

are the rads sludged up at all?

 

[Alfredo]

Try running the pump on speed three (assuming its on 2) one evening. If it cures it then its crap in the system. Its not recommended to leave it on 3 as you will probably get air in the system, but it might help diagnose the fault.

We do find older Solos very sensitive to tripping out on the o/heat..not sure about the newer ones though.

Alfredo

 

[patrickk]

the pump is new and doesn't have any speed settings

 

[patrickk]

could be? how can i prove it and the resolve?