HELO GUYS I AM HAVING MAJOR PROBLEM WITH MY BOILER WHEN CH SWITCHED ON WORKS FOR A MINUTE TO 3 MINS THEN THE FLAME GOES OFF. WHEN DHW IS USED WHILST CH ON FOR THOSE FEW MINS CH WILL STOP WORKING AND DHW WILL NOT WORK. DHW MODE WORKS ON ITS OWN BUT WILL STOP WORKING WHEN CONTINEOUSLY USED. CANNOT HAVE DHW FOR A WHILE AFTER CH FAILURE. HAVE TRIED REPRESURISING VIA FLEX TUBE BUT PRESSURE DROPS SLOWLY AFTER A COUPLE OF HOURS. PLEASE HELP BEFORE THE WINTER BITES HAVE GOT NO CH. BLESS YOU!