Telford 1050 x 450 Indirect Vented Cylinder, designed to be linked to a remote heat source, such as a gas boiler or coal fire. The water within the central heating system is heated by the remote heat source and is passed through the coil in the cylinder. As the primary normally operates at around 80°C, the heat is exchanged into the cylinder and warms the domestic water. Manufactured and fully approved to the latest British Standard specification BSI566:2002 (Part L).