overheating boiler

[lpkelly]

i have a baxi solo boiler that is intermittenly (4-5 times in an evening) tripping out appartantly because it is overheating. this only happens when the heating is on, not when just the water.
we have had umpteen people out to fix and they have changed the sensors, the pump, the motorised valves, p.c.b. and the potentiometer, yet the fault remains. they have all ruled out sludge in the system or any problem with the heat exchanger. can anyone suggest anything even where i can turn to?

 

[twgas]

sounds like a lack of by-pass to me

 

[lpkelly]

we have a byepass which has been checked out o.k. in addition to two towel rails without rad stats. help anyone

 

[gas4you]

Which solo is it?

 

[twgas]

is pump wired back to boiler

 

[bengasman]

sounds like the overrun is too short. turn the boiler setting to minimum to minimum and see if it gets better,

 

[ChrisR]

Um, gas rate, overheat thermostat?

 

[lpkelly]

thanks very much for these.....but
the boiler is a baxi 2pf
the pump is wired to the boiler
the byepass was fitted by a corgi plumber so i can only assume that it is long enough. in addition the problem occurs even with the boiler on the second lowest stat setting.
i am beginning to wonder if i may have a wiring fault
HELP PLEASE this is driving me nuts!!

 

[Agile]

the byepass was fitted by a corgi plumber so i can only assume that it is long enough.

I assume nothing !!!

Even if its a proper auto bypass then it has to we connected in the correct direction and set properly.

Tony

 

[lpkelly]

thank you. is there a formula or something that i can roughly work out the correct/required length' the pipework goes between the flow and return so i am not sure what you mean by direction. can you explain. once again thanks