5.1.3 In case of surface wiring (optional)
Break the surface wiring knockout provided on the receiver before proceeding further
5.1.4 Make connections
In all the following cases for the C1727
• Terminal 1 is hot water off
• Terminal 2 is the common
• Terminal 3 is heating zone 2 or hot water live, if installed
• Terminal 4 is the main heating live
• In a typical single heating zone system only terminals 2 and 4 are required.