Heating
Combi Boiler
In short
Combi Boiler: Combi boiler with 4-core connection (L/N/E/RT). It has 4 terminals: L (Live), N (Neutral), E (Earth), RT (Room Thermostat).
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.
Terminals
| Terminal | What it is |
|---|---|
| L | Live |
| N | Neutral |
| E | Earth |
| RT | Room Thermostat |
How it fails
- Wireless receiver relay failed
The receiver has power and shows a demand, but its relay never passes the live to the boiler.
- Open circuit between receiver and combi boiler
The receiver's output is live but the boiler's RT terminal is dead: the conductor between them is broken.
Where it connects
Lessons that use it
- Spot the Dangerous Wiring
Electrical Fundamentals
Systems it is part of
Also in heating
Your first fault is waiting.
The demo opens with the launch: leave your email and the link lands in your inbox that day.