Diagnostic Guide
Boiler won't start — no hot water or heating
Steps to diagnose why your boiler won't fire up. Common causes and when to call a technician.
1
Check the boiler has power (display screen should be on)
2
Check the system pressure — it should be between 1 and 1.5 bar
3
If pressure is low, open the filling valve until it reaches 1.2 bar
4
Make sure the gas valve is open
5
Press the reset button on the boiler (usually a red button)
6
If it shows an error code, write it down — it helps the technician diagnose faster
⚠️ If you smell gas, DO NOT touch any switches. Open windows, leave the property and call 112 and your gas company.