I do not think this is a sensible idea, but I do not see any code to prohibit it.
I only see code requiring there be at least one shut-off.
Any comments?
So, there’s a shut off for the water going into the WH and another for the water coming out?
That sure would make it easier to replace it. 
OK. If there is no problem, then there is no problem.
Thank you.
I wouldn’t worry about 2 valves , Some people put both sides on to service the tank with out disturbing the whole home. I do not believe it is against code
No problem.
Make sure it is on the cold side.
I think it should almost be standard. Much easier for water heater replacement, especially if unit is located on a lower floor. What’s another $6 when it makes life easier. And I only go with ball valves. None of those gate valves for me. I’ve never found one that didn’t eventually get stuck or leak.
It makes life easier, like Stephen says…no problem.
It’s a good thing and facilitates replacement, especially when multiple units are plumbed in parallel. One unit can be independently isolated and replaced without shutting down the other unit.
Second the preference for ball valves.
There is no reason to have a shut off valve on the hot water outlet of a water heater, besides closing both shut off valves makes a closed vessel.
It does seem a little dangerous to me also. I guess it will become a practical TPR test. :shock:
If they are both closed because the heater is being replaced, where does the heat come from?
It prevents all the water in the lines above from leaking out during heater replacement.
One two many ifs for me. What happens when they are both closed while the heater is on?
You usually drain the tank during replacement anyway, I do not see any real advantage for the extra expense.
What if one’s closed and one’s open and the water heater is tuned on then off then on again? :mrgreen:
Seems the guys who’ve never seen this are in areas with WH in the attic. 
Dammit Rick stop that right now, I can’t think straight.:roll::(:mrgreen::mrgreen::mrgreen:
Not my fault. :mrgreen::twisted:
The pipes would need heat to build pressure, no? Where does that come from?
See post # 12.
What ifffff the home tips over with all the extra wieght of the valves.
Just kidding , Anyway what makes it a open system if there are no open valves? Boilers often have 2 valves installed.
Larry put ten valves in, if you are going with the more valves is better theory. 
I am sure all the water leaking costs waaaaay more than an extra valve and labor.
Two valves seems redundant to me and not as safe as one valve. :mrgreen:
I am starting to think some of the posters are Valve Salsemen. 