A COMPANY managing more than 4,000 council homes is marking central heating boilers with an anti-theft device.

Engineers who service boilers for Dale and Valley Homes, which manages Wear Valley's housing stock, is marking them with SmartWater, an invisible liquid that has its own chemical DNA and can only be seen under an ultra-violet light.

Police will also be making routine checks for marked boilers in scrap yards and during house searches, because stolen boilers are often sold for scrap or reused in people's homes.