• Carbon monoxide is known as the 'silent killer' due to it being colourless, tasteless and odourless. Early symptoms of carbon monoxide poisoning are similar to flu and may be ignored for what they truly are. If not detected carbon monoxide can kill. Over 40 people a year die due to carbon monoxide poisoning.
  • 1. If your carbon monoxide alarm sounds or you suspect a leak:
    • Stop using all appliances, switch them off, and open doors and windows to ventilate the property
    • Evacuate the property immediately; stay calm and avoid raising your heart rate
    • Call the Gas Emergency number on 0800 111 999 to report the incident, or the Health and Safety Executive (HSE) Gas Safety Advice Line on 0800 300 363
    • Donʼt go back into the property; wait for advice from the emergency services
    • Seek immediate medical help; you may not realise youʼve been affected by the carbon monoxide and going outside into fresh air wonʼt treat any exposure by itself
  • 2. If you have misplaced or lost your user manual, you can locate a replacement manual from this list of Vaillant boilers (please have your model number to hand).
  • We update the maintenance tips and troubleshooting guidance from time to time and aim to make it as helpful as possible. The purpose of the maintenance and troubleshooting section of this website is to provide you with general guidance. Please ensure you read and follow our instructions carefully and do not undertake the maintenance or troubleshooting unless you are aged 18 or over, are competent to do so and are confident that you can complete the maintenance. If in doubt do not attempt any actions and where an appliance is gas fuelled refer to a Gas Safe engineer for assistance.

    This website is not intended to be a substitute for professional advice and does not:
    - cover every reason that your product could fail;
    - cover all of the maintenance that can be undertaken for your product;
    - supersede any advice in your instruction manual or from your product manufacturer.

    Do not carry out any maintenance or use the troubleshooting guide if it puts you or anyone else in danger or if you believe it may cause damage to your, or another person’s property.