The Vaillant uniSTOR 150L pre-plumbed slimline cylinder, which has a diameter of just 435mm and is designed to make installers lives a little bit easier, is perfect for houses with limited storage space or difficult access and makes installation quicker and easier in any building. The uniSTOR features a newly created smooth bore coil, placed to optimise heat transmission inside the small unit, to provide optimum performance with a low standby loss of 1.8kW every 24 hours.