I have a gloworm fuel saver and after playing up over christmas, Earlier problem being the hot water and heating system did not seem to like to run together, the longer the central heating and water were on, the radiators seemed to go luke warm, unless the water was switched off and heating for an hour or so and then struck up again. I am now experiencing the problem that even though my boiler will ignite, it switches off about 1 min after, and will then just keep switching on and off. Prior to this, I had noticed the hot water in tank getting particulary hot, the tank temp seems to be arratic when switched on and show a code of PDF. I can hear the pump working, (I think).