Originally Posted by speedball1
Greetings from "Tankless Tom". This is my first post on this site. I started my search on Google with the term: "dielectric union" to try to answer a question I have about the effect their absence may or may not have on the rest of the plumbing in the house, specifically various valves and fixtures.
The house was owned and lived in by our family, but is now being rented out. It is about 40 yrs old. I installed a solar hot water system in about 1982 which is still working but about to spring leaks. We plan to take it all out and install a tankless water in its place.
(I work for the world's largest maker of tankless heaters, so it makes good sense, not that it wouldn't anyway! :))
Okay, the real issue: We recently tried to install a new dishwasher, and found one of the hot water angle stops all rotted when we tried to connect to it. It is only about 15 yrs old. Upon calling in a plumber, he tells us that ALL of them are bad and that the cause was the lack of dielectrics on the gas fired 40 gallon tank that has been in since maybe 1982 also. He installed a set of unions and replaced all valves including even the front main water shut off valve which was apparently bad also!
Does this sound right to you? I am not really doubting that the valves went bad, but I have never heard of the copper to galvanized connection "poisoning" the entire system like he said this did.
Lastly, I am a bit confused with your post above. You say that you come out of the heaters with 3/4 male copper adapters. How can you do that when the top of the heater has 3/4 galvanized pipe coming out?
Also, in another post you say that dielectrics are "good insurance" and even quote "Hammerzone" in your post. Yet you later state that you don't use them in new construction. I'm not trying to cause any trouble, just a bit confused.
Thanks for your patience with this long post,