Circulator pump

They are commonly found circulating water in a hydronic heating or cooling system.

They are specialized in providing a large flow rate rather than providing much head, as they are supposed to only overcome the friction of a piping system, as opposed to a regular centrifugal pump which may need to lift a fluid significantly.

Small- to medium-sized circulator pumps are usually supported entirely by the pipe flanges that join them to the rest of the hydronic plumbing.

Pumps that are used solely for closed hydronic systems can be made with cast iron components as the water in the loop will either become de-oxygenated or be treated with chemicals to inhibit corrosion.

But pumps that have a steady stream of oxygenated, potable water flowing through them must be made of more expensive materials such as bronze.

The tradeoff is the energy wasted in operating the pump and the additional demand on the water heater to make up for the heat lost from the constantly hot pipes.

While the majority of these pumps mount nearest to the hot water heater and have no adjustable temperature capabilities, a significant reduction in energy can be achieved by using a temperature adjustable thermostatically controlled circulation pump mounted at the last fixture on the loop.

These advanced hot water circulation systems utilize a water contacting temperature probe strategically installed at the last fixture on the loop to minimize the energy wasted heating lengthy return pipes.

A second type of system uses a thermostatically controlled pump which gets installed at the farthest fixture from the water heater.

These curves are provided in catalogues and in operation and maintenance manuals, however their stroke is the subject of pump manufacturers warranty.