This was bought as a replacement for my old hot water tank system. The old one had a design flaw. They used a cheap vinyl tube to connect the tank to the expansion chamber & it got stiff/brittle after 3-4 years from the constant heat. This would cause a leak. I had replaced this tube twice. I finally got tired of the mess & hassle, so I bought the newer tank & they finally have redesigned it & no longer use the cheap vinyl tube. Hopefully, this new design will not have the same issues.