Sheep Wool Insulation Eco-Economiser Cylinder JacketWhat is a cylinder jacket? A cylinder jacket is an insulated cover that wraps around your hot water cylinder, also known as your hot water heater or tank. This cosy shield is designed to retain heat and prevent heat loss so that your hot water stays hotter for longer and more importantly, you spend less money heating up water. Cylinder jackets are usually made of synthetic materials like foam or fibreglass, but this Sheep Wool Cylinder Jacket uses