A plumber said brass is better than a dielectric union. Is he right? And how long do I have before I have to replace my pipes?
Let me guess, your plumber failed high school chemistry. Look up cathodic corrosion protection. The whole idea of a dielectric union is to keep the dissimilar metals from forming an electrical connection which would cause one to corrode very quickly. The only way brass could prevent this to join copper and galvanized pipes is if brass happened to be the same metal as copper and as zinc which it isn't. Note that galvanized steel is steel coated (galvanized) with zinc such that if any steel is exposed, the electrical union between the zinc and steel would cause the zinc to corrode instead of the steel, at least until you run out of zinc. The use of galvanized steel is usually screwed up because the tradesmen don't realize that it takes just one scratch through the zinc layer somewhere in the system for all of the zinc to start corroding away, of course, the whole idea of the zinc is that the steel won't corrode till all the zinc has so the corrosion won't be blamed on the guys installing the galvanized product to begin with.
Hate to disagree with your plumber but that's why they make dielectric unions. As far as replacing your pipes goes, that depends on many factors but under most circumstances, the plumbing if correcty installed, should last more years than you'll likely live in the house. Copper, PVC, Pex should last virtually forever, galvanized not quite as long depending on the chemical contents of your water.
you do not want to join copper and galvanized pipes in any way .if the water is heated (as in a central heating system )it will cause chemical reaction and will make the water corrosive .im a builder in the uk .a few years back we built some bungalows .on one of them within 6 months the rads were corroded so much internally that i could crush them with my hand .we replaced the rads and in 6 months they were gone again .i knew a guy at warwick university and gave him sample of the water he said it was like battery acid also said that somewhere on the system there must be a galvanized fitting .we found it in loft connecting a tank .changed it to plastic .solvedwhat is a dielectric union ?
