Watts and Taco Comfort Solutions are two examples of manufacturers that make circulating pumps. They list their hot water recirculation pumps on their official websites, and their products are readily available on home improvement online stores such as HomeDepot.com.
Watts focuses on water circulation, heating and cooling in its products, which include pumps, pipes, valves and other water systems. Watts is a long-standing company that has been in business since 1876.
Taco Comfort Solutions, or Taco Inc., provides similar products to Watts. It creates products such as air elimination devices and remote electronic control systems. Taco has been in operation since 1920.