my potterton puma 80e will not ignite for hot water or c h I've replaced the modulation board and the air pressure switch but this has changed nothing. It was being very noisy before it broke down and the shut down led would come on every time I used hot water, but only after I'd turned off the tap. It always reset again but now, nothing. please can anyone advise me before I buy every new part available in my semi blind search for the problem. jj