I think the best way to test a expansion tank is to not have one. That black crud is not a maybe, its a WHEN.
Here are links from another discussion on those guys, take a look at the interesting products that are made specifically to displace the need for expansion tanks... especially the toilet tank filler-relief valve. Thats a unique one.
So it seems Watts has provided an entire series of options to expansion tanks: here are a few links.
Here is one that really surprised me - wonder if Terry knows of it:
And another surprise - combo ball valve and thermal expansion relief valve for water heaters.
I believe all of those superior to tanks in most conditions, especially the ballvalve with the port for a drain line.
Here is a US Apollo for $50 plus: http://www.grainger.com/Grainger/APO...XZ8?Pid=search
Last edited by ballvalve; Today at 01:31 PM.