Re: Vaillant ecoTEC Plus 831 Condensing Boiler.

Ignition and pump run when cold water taps are turned off.

All functions are working alright except that when the cold taps are run, the boiler fires up momentarily when the cold tap is turned off, then powers down with the pump overrun. What could be the cause of this and what is the solution to remedy.

Edward, September 2012

Have you had any recent changes to your water pipework? The common cause of this is a 'dead leg' in the water pipework.
Think and check.
The other way of sorting this out is to install a non-return valve on to the cold water pipework in to the boiler.

Carefree, September 2012