On my kitchen sink, bathroom sink, and shower, I installed warm up valves. I T'd into the hot water line putting a easily accessible ball valve with the water returning to the top of the water tank (separate water line). Then when you want to use one of the hot water, you open the ball valve and put your hand on it until you feel it get hot. Turn the ball valve off then turn on the normal hot water and instant hot water-no waste of water to warm up the pipes. Good Luck, TomC