Well, I live in a neighborhood about 15 years old. My next door neighbor's gas water heater just failed, as well as my neighbor across the street. Of course the builder didn't spend the extra nickel to put a pan and drain pipe under water heater so I am scared mine failing and damaging all kinds of stuff I have. I know how to sweat pipes and have actually installed a water heater in my old house, but haven't had to deal with expansion tanks, as they are new code requirement. So, I took a look at how my next door neighbor's water heater was installed by professional plumber. The plumber installed the expansion tank horizontally(tank horizontal attached to vertical pipe) which Watts literature says is okay - http://media.wattswater.com/2915054.pdf but only if you support the tank. He didn't, it is just hanging there screwed into T-fitting. I have 2 options to install expansion tank when I buy new water heater next week. If I install the expansion tank vertically, I would have to extend the cold water supply a few feet on the ceiling, and then drop it straight down and back to the water heater. Would that be the best way to install the expansion tank, or should I just install it horizontally? If I do install it horizontally, what is the proper way to brace the expansion tank, given that the support would have to come from the ceiling? The closest wall is a foot or so away and is concrete that I'd rather not tap into.