Circulator pump potential side effects

Technological advancements within the industry allow for incorporating timers to limit the operations during specific hours of the day to reduce energy waste by only operating when occupants are likely to use hot water.Additional advancements in technology include pumps which cycle on and off to maintain hot water temperature versus a continuously operating pump which consumes more electrical energy.Reduced energy waste and discomfort is possible by preventing occurrences of hot water line siphoning in open-loop hot water circulation systems which utilize the cold water line to return water back to the water heater.Hot Water Line Siphoning occurs when water from within the hot water line siphons or is forced into the cold water line due to differences in water pressure between the hot and cold water lines.Utilizing "normally closed" solenoid valve significantly reduces energy consumption by preventing siphoning of non-hot water out of hot water lines during cold water use.Using cold water instantly lowers the water pressure in the cold water lines, the higher water pressure in the hot water lines force water through "normally open" thermostatic crossover valves and backflow check valves (which only prevent cold water from flowing into hot water line), increasing the energy demand on the water heater.

It is important to take note of the increased heat in the piping system, which in turn increases system pressure.Piping that is sensitive to the water condition (i.e., copper, and soft water) will be adversely affected by the continual flow.Although water is conserved, the parasitic heat loss through the piping will be greater as a result of the increased heat passing through it.

Quantitative measures of function 

During pump operation, a droplet flows in the center of the rotor, causing liquid to flow in through the suction port.In the event of an excessive pressure drop, in certain parts of the rotor, the pressure falls below the saturation pressure corresponding to the temperature of the pumped liquid, resulting in so-called cavitation, where the liquid evaporates.To prevent this, the pressure at the suction (at the pump inlet) should be higher than the saturation pressure at the net positive suction head (NPSH) corresponding to the liquid temperature.The following parameters are characteristic of a circulator pump: Capacity Q, pump pressure ∆p (head ∆H), energy consumption P and pump unit efficiency η, impeller speed n, NPSH and sound level L.In practice, graphical relationships are used between the values Q, Δp(ΔH), P and η.These are called pump curves.They are determined by research, the methods of which are standardized.These curves are specified for pumping water with a density of 1000 kg/m3 and a kinematic viscosity of 1 mm2/s. When the circulation pump is used for liquids of different densities and viscosities, the pump curve must be recalculated.These curves are provided in catalogs and operation and maintenance manuals, but their strokes are the subject of the pump manufacturer's warranty.