These closed cooling systems pump chilled water underground through insulated pipes from a central cooling station to commercial, industrial and residential buildings. Heat exchangers are used to transfer the cooling energy from the pipeline to the air conditioning systems located in each building. Over time contaminants including scale, algae, rust, sludge and sand can build up inside the chilled water system pipework, reducing the heat transfer efficiency. Flushing and cleaning of chilled water pipeline systems is a very critical element of any Heating Ventilation and Air-Conditioning Project (HVAC).

This procedure is undertaken to flush out any debris or foreign impurities from the pipeline system both after commissioning of a newly installed chilled water line, and during maintenance operations. Often utility companies undertake flushing of the existing network every couple of years. This is a requisite for their regular maintenance program for the network allowing them to provide cost effective district cooling.