What chemicals would you recommend for Alloy boilers, cleaning and protection, also how long do they last before leaking. I have used fernox mb-1 on 2 Baxi boilers and they both leaked within 5 years. Have I been unlucky or is it the norm. What I would call the penny washers failed on both occasions, the boilers are mainly alloy but the penny washers are tin , why do they not use stainless steel or an alloy blend for the penny washers, I am sure the boiler would then last a very long time. I know its not in manufacturers interest for the boilers to have a long life, the old cast boilers lasted some times over 50 years. Can we not make a boiler these days that will last over 15 years on average, instead of the 7.