nest Learning Thermostat Installation Manual page 6

Install the Heat Link
3. Connect to power
Take a look at the wiring in your heating
system to determine what type it is.
Connect the L (live) and N (neutral)
connectors on the Heat Link to the L and
N connectors on the boiler or junction
box. This will power the Heat Link.
TIP: If there are multiple heating
zones in the home, each zone valve
will need its own Nest Thermostat
and Heat Link.
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4. Connect the control circuit
Connect the heating control circuit to
the Heat Link 1 (satisfied), 2 (common),
3 (call-for-heat) as needed.
If the system has a hot water control
circuit, connect it to 4 (satisfied),
5 (common), 6 (call-for-heat) as needed.
If you have an OpenTherm boiler,
connect its control circuit to the OT1
and OT2 terminals.
→ See pages 20-27 for detailed wiring
diagrams for these system types:
230 V combi boiler
Low voltage/dry contact combi boiler
S-plan
Y-plan
OpenTherm boiler
District heating with electrical
control valve
5. Connect to the thermostat wires
If you're installing the Nest Thermostat
in a new place, skip this step.
Take two wires from the wire bundle that
goes to the current thermostat and
attach them to the T1 and T2 terminals
on the Heat Link.
HEATING
Call-for-heat
Common
Satisfied (optional)
12 V DC power
Earth
OpenTherm (42 V DC max)
HOT WATER
Call-for-heat
Common
Satisfied (optional)
230 V AC live and neutral
input power
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