I just replaced my 16 year-old AO smith with a new AO smith water heater. Now that I have it installed, I realize I need to add an expansion tank after never having one in my house, built in 1996. My question is about the valve I replaced on the cold inlet pipe to replace the original valve. I grabbed a stop valve sweat with the arrow without thinking and now I question whether or not that is good/bad for the water heater?? Whether it should be replaced? I'm trying to correct any mistakes if I have to go cutting pipe for the new expansion tank.