BES stock the correctly sized expansion vessels to meet your needs. Including our new range of robokit compact vessels for when space is tight. Both types are 8, 12, 18 litre capacity vessels with the standard range having 24, 35, 50, 80, 105, litre capacity. All kitemarked to BS 4814. We also stock safety relief valves, mounting brackets, filling loops and sealed system filling kits.