Power Flush Machines

Power flush machines clean wet central heating systems by pumping water and cleaning chemical through the pipework and radiators at a high flow rate. They shift sludge, rust and scale that cause cold spots, poor circulation and boiler noise, and they are often used before a new boiler is fitted. This category includes flushing machines, powerflushing cleaners and magnetic filters made to work with them.

How power flushing works

• Connection: the machine connects into the circuit, for example in place of the circulating pump, at the boiler connections or at a radiator.
• Flow reversal: a lever reverses the direction of flow at intervals to loosen deposits from both sides.
• Radiator by radiator: each radiator is flushed on its own with the full output of the pump.
• Dumping: dirty water is dumped to a drain while clean water replaces it, until the water runs clear.

Choosing a machine

Compare the pump flow rate, tank capacity, maximum operating temperature and the hoses and fittings included. Machines are made in 230V and 110V versions; reduced voltage 110V equipment runs from a transformer and is widely used in construction. A magnetic powerflushing filter in the circuit captures magnetite during the flush and shows what has been removed.

Finishing the job

When the system runs clean, refill it and add a corrosion inhibitor. This follows BS 7593, the code of practice for treating water in domestic heating systems, and when a new boiler is commissioned the checklist records that the system was flushed, cleaned and dosed with inhibitor. Follow the manufacturer's instructions and safety data for the machine and the chemicals. Work on gas pipework, appliances and their gas parts must only be carried out by a Gas Safe registered engineer.

For chemicals and filters, see central heating cleaner and central heating filters.