Modern wood heaters use a clear ceramic material instead of the tempered glass that older fireplaces used. This ceramic material is usually called heater glass for simplicity. It will not break with heat generated by wood burners, but it can break if the fasteners are over-tightened or if it is struck hard with a poker or piece of wood. The glass must be sealed tightly to the door to prevent air leaks. This is normally done with a flat woven gasket, usually with adhesive on one side. Clean the glass before installing the gasket. Remove the paper backing from a length of gasket and lay it on a flat surface, sticky side up. Center the edge of the glass along the gasket and press it into the adhesive.
Now rotate the glass and press the next edge into the next length of gasket. Repeat until you get back to where you started and cut the gasket to the right length. Now wrap the edges of the gasket around the edges of the glass. The glass gasket will need replacement at some point, but usually not as often as door seals. If you see brown streaks on the glass coming in from the door frame, replace the gasket. Here is the glass, with gasket installed, being mounted in the door frame. heater glass is very expensive, but should never need to be replaced, although some heater models seem to cause etching of the glass with normal use over time. You may wish to replace it to renew the clear fireviewing. Regular maintenance and replacing glass will require you to tighten glass fasteners. When so doing ensure that you tighten them lightly, allowing room for the glass to expand when heated. If you crack your glass, in many cases the heater may be used for a short term while you find a replacement. Replacement glass can be cut to size at our factory.