Having same problem. Potterton promax condesing boiler fitted june 2013. Flame changes from blue to orange then seems to run ok. Had engineer out was working ok. Recorded sound to show engineer when he comes back out.
I am having same problem. Vibrations coming from boiler blue light changes to orange. After a few minutes ok. Very frightening. Had engineer out was working ok. Seems intermittent fault. Any clues? Potterton SL Condensing boiler fitted june 2013.