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Chimney and Flue Systems

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  • Please note that the flue system information provided within this section should be used as a guide only. We strongly recommend that you acquire a professional fireplace survey prior to the purchase and installation of any stove or fireplace.

    Once you know what chimney type you have you will need to check the integrity of the chimney stack and may need the appropriate chimney flue liner. Our Twin Wall section explains the difference between these liners and will help you understand what grade of chimney liner is required for your chimney and flue system.

     Class 1  Class 2  Pre Cast Flue  No Chimney
     Class 1 chimney  Class 2 Chimney  Precast Chimney  No Chimney
    Commonly used in houses pre-dating 1960. Class 1 chimneys are identified by 7” (180mm) diameter, or greater flue. Ensure the existing chimney is structurally sound before any installation procedure. Used in either an older house, where the existing chimney has been lined by a proprietary steel flue, or a newer house with a steel flue built-in. This chimney type can be identified by a 5” (130 mm) diameter flue and a steel flue terminal. Modern houses, built later than 1960, often have a pre-cast concrete chimney system, which is identifiable by a rectangular box section flue and a terminal, as illustrated in the picture. Modern houses are often built with no chimney. This means that you can only use a modern decorative electric fire with up to 2kW heat output, a gas powerflue fire, or a flueless gas stove.