In process of investigating intermittent fault with hot water system. Suspect it may be the cylinder stat (the type that is strapped around the hot water cylinder) and for the price of them (£10-£20) seems to be a no-brainer to fit a new one. Existing one is a Satchwell SA36, and very old (temp dial is in Farenheit). Is there any particular brand/model of stat that I should buy, or avoid, or are they pretty much of a sameness? Best place to buy them too, please.