hi there seen that you give good advice on here need help with my boiler, driving me mad .. not as much as my dad who keeps on thinking he can fix it but really doesnt know what he is doing LOL bless him! i havea valliant ecottec pro 24 and its showing a f22 problem , the boiler has a silver filling loop but only one black tap on one end, when i turn it it doesnot let the water in !!! ??? i think i am menat to turn a second tap/ vaulve but dont not which one ?? please help !!