Taco Plumb n' Plug®Circulators periodically re-circulate hot water through the domestic piping system to decrease the delivery time to outlet fixtures and reduce wasted water. These UL-listed units feature quiet, efficient operation and low power consumption. Self lubricating, with no mechanical seal and Taco's unique replaceable cartridge design, Plumb n' Plug® circulators are field serviceable and maintenance free.