Boiler Help Please

[timdiy]

I am looking for some advice please.
Baxi Solo2 80PF

System works fin then after a couple of hours, the system sometimes does not work.
When this happens, I have checked:
Fan - OK
Pump - OK
Pilot - On
Timer - Calling for heat
Room Stat - Calling for heat.
But no boiler burning.

To get to work, any of the following works.
Shut the power off and back on.
On the timer, advance to off, can then hear fan shut off, then advance again and all will be fine.
Turning the boiler control down to Zero, then back up again.

Any suggestions on what the problem is please?

 

[dcawkwell]

Boiler thermostat at a guess.

 

[timdiy]

Thanks. Would that be the boiler overheat thermostat or overheat stat?

 

[dcawkwell]

Thanks. Would that be the boiler overheat thermostat or overheat stat?

Just normal boiler thermostat.
It thinks it is still hot so not switching on.

 

[FiremanT]

I would prefer valve

 

[timdiy]

Thanks both. I assume you mean the gas valve, so not for a DIYer?

 

[timdiy]

For starters took the quickest, cheaper and easier option firt. Changed the boiler thermostat. Now been running 48+ hours with no failure to burn. Fingers crossed. Thanks all.
It was failing ignite probably 3 times in 24 hours.