hi my myson boiler has packed in again, it is at least 25 years old so had my moneys worth. although over the years its had 3 3 way valves 2 controllers 4 thermocouples etc. now i carnt get it the main burner to ignite. so i wish to buy a direct replacment type boiler (so i can keep my cistern tank etc.) my question is on these type of new boilers does the gas feed to it need to change. at the moment it is approx 20mm this reduces to 12mm to feed the cooker and my boiler thanks