This plumbing design requires the hot water side of each fixture (faucet, shower or other appliance) be placed in a continuous loop by connecting a hot water return line from the last fixture to the water heater.
Wilo Hot Water Cast Iron Circulator 10 GPM 3-Speed 1/8 HP # STAR-S21F. Quiet maintenance-free performance. Low energy consumption, UL/CSA listed. Functionally replaces Grundfos 15-58FR, Taco 009-F5, Armstrong Astro-70 and Bell & Gossett NRF-22