As you stand around waiting for hot water to arrive at your bathroom sink—or, worse, wander off to do something else while the tap is running—watch what's flowing down the drain: not just water, but all the energy that went into heating it. But let's say you could press a button and have hot water in an instant. That's the work of a clever device called an on-demand recirculating pump. Installed under the sink, the pump captures the not-yet-hot water before it exits the tap and shoots it back to the water heater. The process repeats until the water gets hot enough, at which point the pump shuts off, you turn on the tap, and the steamy stuff flows. Obviously, this setup saves water.
Less intuitively, it also saves energy. That's because the water going back to the heater is usually slightly warm, so reheating it takes less energy. And the pump moves water faster than a typical faucet can, which means less heat loss in the pipes‚ and less waiting time for you.
Metlund D'Mand S50 Recirculating Pump:
$375 (includes all fittings for copper pipe)