Low Vent Pipe

Whenever I carry out a Powerflush I always investigate the cause of the excessive sludging up of the radiator system. One classic cause is that the vent pipe above the feed and expansion cistern is not high enough. 

When this is the case the primary water expands and pumps over into the cictern, this introcuces air bubbles which are carried into the system helping the corrosion to occur. The red/brown sludge in the water is ferrous oxide i.e. rust.

By extending the height of the pipe to the regulation height of 450mm above the fill level, for fully pumped systems,  this pumping over is eliminated.

Regular bleeding of the radiators will also reduce corrosion.

Remember without oxygen rust cannot form so the less air in the system the better.

The reason for the odd shape to the new vent pipe is that a roof beam was situated just above the cistern which is probably why the original vent pipe was so low.

Before                                                        After