High
BUBNEB STAYS ON on Chaffoteaux Britony Duo 55

Your boiler is failing to ignite properly because debris or trapped air is interfering with the gas or water flow, meaning your heating and hot water will not work.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

I) Air in pipework; II) Gas valve stays open; III) Venturi blocked; IV) Dirt on gas valve facing; V) Loose jumper on house stop cock tap; VI) Dirt foreign matter is water section; VII) Slow ignition device stuck

From this model's manual
Verified against the Chaffoteaux Britony Duo 55 installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Find a Gas Safe engineer
Search the official register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like BUBNEB STAYS ON: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Related guides you might find useful

No hot water but heating works

Almost always a stuck diverter valve on combis.

Read →

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →

Pilot light keeps going out

Older boilers — thermocouple, draught, gas supply.

Read →