Hot Water Recirculation Pump

 We added a hot water recirculation pump to our master bathroom.

This pump is designed to take water from the "hot" water pipe, and shove it into the "cold" water pipe. There's a built-in therostat, so when hot water from the water heater arrives at the pump, the pump shuts off. The system is designed to run continuously, which is nice for always having hot water, but both wastes heat from the hot water (becuase the builders of this house didn't bother to insulate the hot water lines, and uses electricity throughout the day.

I put our reciculating pump on a smart plug, and put a button next to our shower:

Now, rather than turning on the shower and waiting for the water to get warm (and not always being prompt about getting in the shower once the water is warm), we can push the button, and five minutes later the water is hot, with none of it going down the drain!

This actually had a noticeable impact on our water bill. And since our sewer charge is based on water usage in the winter, it's a double win!