How do I wire the 3 wires from old Sunvic tlx 2259 temperature stat to the new tower rfnp thermostat which has 5 terminals. Old wires are in live neutral and a yellow wire. The new options are L N and 3,4,5. Tried different combinations but nothing seems to work. The new receiver has power and seems to connected to the separate temp unit but it does turn on the central heating... Any help advise appreciated