Provides automatic temperature control of domestic wet central heating systems. Used either as a direct switch for circulating pumps and boilers or to operate spring return and motor open/motor close zone valves. Features dual-diaphragm temperature sensing element. 10 to 30°C Temperature Range Suitable for All Boilers 3-Wire Installation Mains-Powered Without Display Insulated Without Frost Protection Fits Custom Backplate Heat Anticipator for Close Temperature Control Change-Over Contact Switching 10 to 30°C Temperature Range Suitable for All Boilers 3-Wire Installation Mains-Powered Without Display Insulated Without Frost Protection Fits Custom Backplate Heat Anticipator for Close Temperature Control Change-Over Contact Switching