As soon as a heating central heating system is filled with water deterioration of the system begins. The combination of water, air and a variety of metals and installation contaminents such as flux can result in internal corrosion, sludge formation and scaling. Powerflushing is a highly effective method of removing harmful deposits.

Symptoms of corrosion and sludge deposits.

  1. Central Heating system is slow to warm up
  2. “Kettling” noises from the boiler
  3. Radiators partially cold
  4. Radiators fail to heat up
  5. Radiators require frequent bleeding
  6. Central heating water is dirty and discoloured
  7. Pump failures
  8. Valve failures or incorrect operation


Ideally a powerflushing pump is connected to the central heating by replacing the circulatory pump. However, it can be done in other ways such as across a pair of radiator tails.

The powerflush pump works at low pressure but pumps the water at a much higher velocity than the is usual through the central heating system. The fast moving water loosens the harmful deposits and suspends them in the water. This water is returned to the pumps resevoir where it is can be removed from the system.

Powerflushing is made more effective with the use of cleaning chemicals that help break up the deposits. Reversing the water flow will disrupt the normal water flow and in conjunction with rapid reversal of the flow creates turbulance that dislodges more deposits.

Advantages of Powerflushing

The powerflush pump is fare more effective than conventional chemical treatments and drain-down techniques for the following reasons.

  • The central heating system is not emptied of water and so air-locks and other filling issues are avoided.
  • The pump effectively clears pipes that are below the drain-down point.
  • Every radiator can be individually flushed by opening them individually.
  • Continuous flow of water allows monitoring of the turbidity of the water throughout the process to achieve a known end point.
  • Much quicker than drain-down methods.

It would be wrong not to mention some of the disadvantages of powerflushing. The system is highly effective and the downside is that it will find many weaknesses in an old system. These can be radiator valves that may start to weep water. In the worst case it can find highlight where radiators have pin-hole corrosion which have become blocked up by debris. These failures will happen eventually, so finding them with a plumber on-site is usually beneficial, if a bit annoying in the short term.

Powerflushing and Boilers

When installing a new boiler an existing central heating should be flushed. Powerflushing is a recognised method to comply with best practice standards. Modern boilers have very fine water passages in the heat exchangers and only very small amounts of debris can cause them to block reducing the efficiency of the boiler.

The use of high velocity water means that effective flushing can be achieved with less aggressive chemicals. This is very important for boilers fitted with aluminium heat exchangers..


Once cleaned a central heating system must be treated with a good quality corrosion and scale inhibitor. This will help prevent further corrosion and returning to a poorly functioning system.

Powerflushing other Installations

A powerflush pump is well known for resolving central heating cleaning problems. However, it can also be used to flush other installations. Examples would be new water installations in buildings such as domestic hot and cold water supplies where connection to the mains may be prohibited. In such systems, chemical treatments can be used to remove bacterial growth.