Viessmann Vitodens Condensing Boiler Cover Insulation Board Type 0 – Duraboard Ceramic Fiber Insulation Plate

This is the duraboard ceramic fiber insulation plate used in the combustion chamber cover of Viessmann Vitodens condensing boilers. Known in the field simply as the asbestos board, this part limits heat transfer between the cover and the combustion chamber and keeps the heat of the flame in the combustion zone. Plates manufactured today do not contain asbestos; they are ceramic fiber based.

The round plate has an opening in the middle for the burner throat, three notches on its edge, and an oval slot and a straight-cut edge section on the top (as seen in the photos). These notches line up with the fixing points on the cover.

When Should the Cover Insulation Be Replaced?

• If the plate is cracked, broken at the edge or crumbles by hand.
• If it sheds pieces every time the cover is opened, or its surface is dusting.
• If the plate has been deformed or dislodged during burner, heat exchanger or cover gasket replacement.
• If darkening, overheating or a burnt gasket is seen on the combustion chamber cover, the insulation is also checked.

Dimension Comparison and Installation

• In Viessmann condensing boilers, cover plates are produced with different diameters and notch layouts depending on the model family. Before ordering, the outside diameter, center opening, number of notches and position of the oval slot of the removed plate should be compared with the photos.
• The ceramic fiber plate is fragile; it should be carried flat and not pressed at a single point.
• Before installation, old plate residue and soot on the cover surface should be cleaned off.
• The plate is not forced into place; the notches and center opening must line up with their seats.