nest Learning Thermostat Installation Manual page 14

OpenTherm boiler
Power supply
for Heat Link
N L 1 2 3
230 V/50 Hz
3 A fuse
mains
L
N
OT boiler
26 26
Only required if you
have existing
thermostat wires
4 5 6 OT1 OT2 T1 T2
12 V power to
Nest Thermostat
District heating with electrical control valve
Power supply
for Heat Link
N L 1 2 3
230 V/50 Hz
3 A fuse
mains
L
N
N L
District heating valve
Only required if you
have existing
thermostat wires
4 5 6 OT1 OT2 T1 T2
12 V power to
Nest Thermostat
27