Combi · wiring diagram
Combi boiler with a wireless thermostat wiring diagram
In short
A combi boiler heats the radiators and makes hot water at the tap, so there is no cylinder and no hot water valve. From outside it needs a supply, and a switched live for the heating on its room thermostat terminal: from a room thermostat or a wireless receiver’s switch, or, with two heating zones, from the zone valves’ end switches.
A combi boiler with a wireless room thermostat and its receiver, wired. No timer on the canvas: an installation needs one too (Boiler Plus), often the boiler's own plug-in clock.
This circuit, wired in the simulator. Wire colours as the lessons teach them. The meter reads what the circuit is doing.
Every wire, terminal by terminal
| From | Terminal | To | Terminal | Colour |
|---|---|---|---|---|
| Fused Spur | L | Combi Boiler | L | Brown (live) |
| Fused Spur | N | Combi Boiler | N | Blue (neutral) |
| Fused Spur | E | Combi Boiler | E | Green/yellow (earth) |
| Combi Boiler | L | Wireless Receiver | L | Brown (live) |
| Wireless Receiver | N | Combi Boiler | N | Blue (neutral) |
| Wireless Receiver | E | Combi Boiler | E | Green/yellow (earth) |
| Wireless Receiver | 2 | Combi Boiler | RT | Black |
Where it connects
Lessons that start from it
- Quick Jobs
Quick Jobs
Call-outs on this system
Other systems
- S-Plan
S-Plan
- S-Plan with a digital room stat
S-Plan
- Wireless S-Plan
S-Plan
- S-Plan with a frost thermostat
S-Plan
- S-Plan Plus
S-Plan
- Y-Plan
Y-Plan
- Y-Plan with a frost thermostat
Y-Plan
- Combi boiler with two heating zones
Combi
Back to every wiring diagram.
If this is your home: this page is written for heating engineers. Mains wiring and gas appliances are not DIY jobs; call a Gas Safe registered engineer. If you smell gas, leave the building and call the National Gas Emergency Service on 0800 111 999.
Read the explanation
- Wiring a wireless thermostat to a combi boiler: the receiver, the link and the room-stat terminals
A combi needs only its supply and a call on its room-stat terminals. The receiver’s relay replaces the link; check volt-free against mains-switched first.
Practise it in the simulator.
Runs in the browser on a laptop or desktop. Cancel any time.