Chilled Water System Flushing Procedure

Flushing with water at sufficient velocity will remove loose scale. It will not remove surface rust. In carbon steels, without inhibitor, it will cause rust.

Chemical cleaning is required to remove rust.

It is important to fully survey the system before flushing commences. In almost every case, flushing will be carried out at the normal system operating velocities – or faster. Equipment sensitive to damage from high-speed swarf/slivers of metal, large volumes of scale/dirt should be removed before flushing commences. Likewise, restriction orifices and anything else that could impede the flow should be taken out. Where applicable, strainers should be fitted to protect pumps and other equipment.

Ordinarily, HVAC equipment is completely isolated during flushing until 100% of the pipework is cleaned.

It depends on the size and complexity of the system – and which processes are required. Typically, flushing can take anywhere between 1 day to 2 weeks.