In hot water mode everything seems to function as it should however when central heating is required the boiler burner ignites but only runs for ten seconds then the flame goes out if you leave the boiler in central heating mode the burner intermittantly comes on but only for 5 to 10 seconds. There are no led flashing. I can say that the pump is working and the electric fan the central heating sensor has been replaced. ANY IDEA'S PLEASE.

IAN A, September 2009

It's the DIAPHRAGM PRESS/DIFF VALVE product codes 439519 from the plumb centre, BAXI code 248066 cost is £6.44 from the plumb centre, I've had three boards fitted numerous other parts fitted.
Found this info on another forum done it myself only takes 10mins.
A plumber quoted another £400, I've spent over £1200 on repairs in the last two years. All for the want of a £6 part.

Julie, October 2009

id check min gas pressure but you'll need an engineer. basically hw comes on and runs in full gas mode where as ch comes on full then within couple of secs should lower towards min gas pressure which could be the problem. If the pressures are correct when checked id be looking towards sensor perhaps,

ste, September 2009