Secondary Return Pump
A secondary return pump is used as part of a hot water recirculation system. The simple function of a secondary return pump is to draw or pull the hot water that has cooled down through heat loss from long pipe runs back to the hot water cylinder for reheating so that hot water is available almost instantly at the hot water outlets or taps, so that you are not waiting long periods of time for it to travel from the hot water cylinder to the taps.
In this secondary hot water recirculation an additional pipe or pipes are required to run back from the furthest outlets back to this secondary return pump, that is usually located close to a cylinder. A non return valve is also required after the pump as well as isolation valve before the pump and after the non return valve in order for maintenance of the secondary return pump.
Secondary return pumps must be made of non-ferrous materials for the parts that are in contact with water. The back housing is usually in most contact with the water as well as the impeller. So the housing ( back part of pump) must be made of either bronze, stainless steel, or plastic. These materials by standards should be wras approved, although technically if the materials is as mentioned then it will be suitable. The impeller can be stainless steel or plastic. The shaft must also be stainless steel or equivalent.