Saw somewhere that it’s not allowed in Chicago, but no problem in the rest of Illinois.
Other threads…
http://www.nachi.org/forum/f2/valves-both-sides-water-heaters-43260/
http://www.nachi.org/forum/f2/hot-water-two-valves-ill-try-once-more-43266/
*added…
LOL, just realized I was a bit late to the dance. 
8/6/09, 1:05 AM