It takes a few minutes for my tankless water heater to warm up, so we end up wasting a lot of water in our shower. Is there a way to avoid this? A friend mentioned a “comfort valve” or something? What is it and how does it work? Or is there another solution? Thx!
That fitting is installed between the hot and cold supply lines at a single location/fixture in the house, usually the farthest away from the heater. Then, a compatible tankless heater can use a pump to push hot water out while pulling the cold water back in through the cold supply line - so no extra recirculating pipe has to be installed. You trigger the recirculation with a switch at the fixture, on a schedule, or with an app/smart home device.