Woodstove problem: cracked or broken glass

Although there are countless different models of wood stoves, there are relatively few basic types of stoves, and the mechanical problems they experience are similar.  Your first step in caring for your stove is to read your owner's manual for specific information on your model of stove. If you don't have a manual, look for a label on the back of your stove that identifies the manufacturer and model, (or snap a photo of it if you can't find any label) and go to your local stove shop. You may be able to purchase a manual. 

Here we will discuss some of the basic categories of problems you might experience, and what to do about them. We will cover:

Cracked or broken stove glass

Under normal conditions of use, the stove glass will not crack or break. Causes of glass breakage are:

  • Severe over-firing of the stove.
  • Impact (hitting the glass with a log, or slamming the door into a protruding log).
  • Spilling cold liquids on hot glass.
  • Improper glass installation.

The first three are obvious, but the fourth bears comment. In most stoves, the glass is held in place with steel clips or a cast-iron or steel frame around the glass. There is a gasket between the glass and the door, but not always between the glass and the clips or frame. If the frame is over-tightened or unevenly tightened, especially in doors that use clips, the glass could break from stress. 

Picture a piece of glass held in with small metal glass clips, two of which, opposite each other, are cranked in gorilla-tight. As the temperature of the stove and metal clips increases, the clips expand, exerting pressure on two points of the glass. This is an almost sure- fire way to break the glass, and it will usually crack from one clip to the other. 

So if your stove glass breaks, before you take all the pieces out, take a look at where it broke. It may offer a clue to the cause. (But first, ask if anybody slammed a log into it...) 

Obviously, you need to replace cracked or broken glass. If it has been a long time since you have re-gasketted around the glass, now's a good time to do that, too. 

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