Not quite as effective, but even easier is that you can get a back-flow preventer valve (approximately $10 worth of metal) that allows the hot water to push int

Not quite as effective, but even easier is that you can get a back-flow preventer valve (approximately $10 worth of metal) that allows the hot water to push into your cold water (but not the reverse) As I understand it (and I am NOT a plumber) -- when you turn on the hot water, it pushes hot water up the line. Turn off the water, and that water will cool. But, if you add a one-way valve that allows flow from hot to cold, it will allow the higher pressure hot water line to flow into the cold water line so that it keeps hot water to the tap so that you don't have to wait (in my case) 5 minutes to flush out the cold water that has accumulated before getting to the hot water. A plumber friend suggested this to me when I complained about my master bathroom (the furthest in the house away from the heater) taking SO LONG to warm up. Then he came out and installed it in about 15 minutes (which would probably amount to a one hour minimum charge for a plumber not doing it for free) plus a $10 part he had us buy on Amazon. TLDR, now instead of taking 5 minutes to heat up from ice cold to warm to eventually hot, the hot water is warm from the second I open it, and hot within about 15-20 seconds.