: They are not "stub outs", they are air chambers and are to minimize water hammer when the valve is closed quickly. Their effiveness is limited, in that once the air is absorbed into the water, there is no way to restore it. In this area, no one uses air chambers and the systems work quite well. So, in your case, I would not worry unless you develop shutoff noise problems.

: : What are the ramifications of not inserting "stub-outs" (at least that's what I think they're called) in the hot and cold supply lines going to a shower valve? By "stub-outs", I mean the copper pipes that "T" off of the main hot & cold lines and travel upward a few inches to a dead end just beyond the valve. I obviously failed to do so. How bad a situation am I in???

: : Thanks!!