Hi. I'm new to the forum but hope I can get some advice. I have a Glowworm 24 ci boiler (yes unfortunately). I keep getting a intermittent fault when the hot water is switched on (f19 NTC not attached) heating is running ok.Fault first occurred in january - I replaced the thermistor and it was ok for 8 months though heating was not used as much during that period. Fault has now returned and is occuring more often . Switching the boiler on and off resolves it. The board (reconditioned) was changed last December. Is it worth buying another thermistor for £18 or is it more likely to be the board as fault never ocurred until board was changed or could it be another problem? Board is just out the 12 month warranty the company provided. Any advice would be appreciated. Thanks Chris