• 1. Any of the following could be a sign of CO in your home:
    • Flames of a lazy yellow or orange colour on your gas hob, rather than being a crisp blue;
    • Dark staining on/around appliances;
    • Your CO alarm (if you have one) activates;
    • Increased condensation inside windows.
  • 2. Issues such as carbon monoxide poisoning can be fatal. But many people are not aware of the warning signs, particularly older people, who may put flu-like symptoms or simply feeling drowsy, down to old age. Symptoms of carbon monoxide poisoning include:
    • Nausea
    • Light-headedness
    • Headaches
    • Shortness of breath
    • Dizziness
    • Sleepiness
  • 3. 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.