Expansion Tanks: where/how do they fail?

[hidden 1]

if it was done in Ill i bet it would not be covered(flood insurance ,codes,etc) unless it was installed as state required....if i have to change mine ill turn off the valve before tank tee, let out all hot water /pressure ,turn off power,then change it out easily(i use a flex line on mine-above heater)-15 minutes..
-and i do this every so often on a regular basis -3 or so yrs..unless i see a problem.

[shorton]

The valve handle is 9' in the air, it is out of reach of accidential or curious shutoff. I'm confident I could get a PE stamp on it if I needed one. But that would be overkill to say the least. Now the tank is trivial to change. I have a pressure gauge co-located. Should the gauge fail or leak, I have a hand tightenable cap that can be installed in seconds cabletied at it's T. The ball valve has no moving parts and if it failed, it would fail in it's current position, open. I'm comfortable with this install. In the future (i.e. sale of home), should anyone have a problem with the valve, it's simple enough to remove. But a local home inspector (w/PE) here had no problems with my install, actually liked it and the way I had the tank, and pressure gauge in a conspicious location where the owner (me) could see both the tank install date written on the tank, and the current pressure. And since I've made it easy to replace the tank, I'm more likely to do it on a periodic basis.

[Cass]

If you don't shut down the system and just close the valve the tank will be under pressure and what a mess you will have...you still will have to shut down the heater to release pressure in the exp. tank...if the valve is above the tank but on the cold water line you will still shut down the heater and release pressure before removing the tank...a valve on an exp. tank does little to help with replacement and could accidentally be closed during operation rendering it useless.

[shorton]

If you don't shut down the system and just close the valve the tank will be under pressure and what a mess you will have...you still will have to shut down the heater to release pressure in the exp. tank...if the valve is above the tank but on the cold water line you will still shut down the heater and release pressure before removing the tank...a valve on an exp. tank does little to help with replacement and could accidentally be closed during operation rendering it useless.

You have that right! . Anyone who just turned off the valve and unscrewed the expansion tank would show a complete lack of understanding of how it works. And if they don't they shoudl have hired a pro anyway.