Boiling over into Header tank?

My Potterton 16-22 with similar problem. redhot pipes rads & boiler blasting water into the header tank splashing out soaking the loft floor. Running normal today after changing the thermostat. after a lot of thought I decided the stat was the only temperature/safety device on the boiler.
My boiler starts flames & heats for 2.30 minutes then stops for 7.31mins to dispel the heat, I feel sure your boiler should stop itself if it gets to hot. pump running or not.

Jim R
December 2008

Thanks Tony S ,if the pump is stuck how do I resolve this ?

Malcolm Foster
November 2008

Are you sure the pump is running and not just humming.It sounds like it has stuck and as you say the only place for the water to go is over the expansion.

Tony S
November 2008