Domestic hot water in pipes will cool due to heat loss when there has not been a withdrawal for quite some time. In large domestic hot water systems, where the distribution piping is extensive, it will take a relatively long time to remove this cool water from the pipes before the hot water can be withdrawn. Due to comfort issues, this is often not acceptable.
Circulation of domestic hot water ensures a flow inside the pipes, even though hot water is not withdrawn. In this way, the waiting time is kept to an acceptable level. The domestic hot water is circulated at a given minimum temperature to minimise energy consumption. This is controlled by a circulation valve, strategically placed several places in the domestic hot water system. A circulator pump is used to keep the domestic hot water circulating back to the production system (heat exchanger or water heating unit).
Care taken to minimise bacterial growth in the pipe system often makes it necessary to establish circulation of domestic hot water at a higher temperature. Systematically increasing the temperature in the domestic hot water system makes it possible to destroy some of the undesired bacteria. In larger domestic hot water systems, circulation may conveniently be managed by a BMS.
Grundfos circulating pumps for hot water include circulator and water transfer pumps. These ensure optimal domestic hot water production and recirculation.