Woodstove problems: dampers

Author – Todd Woofenden

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:

• Damper malfunction
• Broken/stuck/loose handles
• Warped or broken parts
• Cracked or broken glass
• Worn or missing gaskets
• Malfunctioning catalytic combustors
• Poor performance
• Wood stove damper malfunction
• Bypass Damper

Handle moves, damper doesn’t

If you can move the handle of your by-pass damper, but the damper is stuck open or shut, there are three possibilities:

Disconnected or loose wood stove damper linkage

The handle is usually connected to a bar or lever that pushes up against the damper blade when you turn the handle. (The damper blade is the metal plate that opens and closes.) Sometimes there are several components leading from the handle to the damper blade, and one might have become disconnected, or loose enough that it isn’t engaging the damper blade any more.

Broken damper linkage component

If someone has forced the handle of a stuck damper, a part may be broken.

Warped, broken, or misaligned damper blade

Especially under conditions of regular over-firing or rough use of the stove, the damper blade sometimes warps, breaks, or comes out of its proper seat, so the linkage no longer engages the blade. 

In any of these cases, you have two choices: hire a chimney professional to examine and repair the stove, or try to do it yourself. Some damper linkages are easily accessible, and others are nearly impossible to get at. An exploded diagram of the stove will be especially useful. Ask at your local stove shop if you don’t have one in your owner’s manual. 

Bypass damper: handle is stuck

If the damper handle is stuck, don’t force it! You could bend or break it, creating a much bigger problem. There are three basic causes of stuck bypass dampers:

Damper blade is warped

If the blade is warped from over-firing of the stove, it might become stuck in place. Sometimes this happens only when the stove is cold, or only when it is hot. This is due to the expansion of the metal: In one position or the other, (hot or cold) it might hit another component of the stove, or bend out of shape enough to prevent smooth operation.

Linkage Is broken, bent, or improperly connected

Sometimes a damaged or improperly-connected component will jamb the linkage.

Improperly adjusted mechanism

Some dampers have adjustable devices such as snap-locks that hold the damper in the closed or open position to help prevent accidental movement of the damper, or tabs on the back of the damper blade that engage the damper linkage. If these are too tight, the damper could be stuck open or closed. 

Again, the solution is to examine the damper and linkage, and repair/adjust/or replace as needed. A properly adjusted bypass damper should operate smoothly and easily. 

Pipe damper

Handle moves, blade doesn’t

Most pipe dampers are connected to the handle by friction: the steel rod that passes through the stovepipe has a small ridge on it that pushes up against a corresponding indent in the damper blade. A spring on the handle outside of the stove pipe puts tension on the rod, keeping the rod engaged to the blade. (Take a look at it next time you have the stovepipe off for cleaning, and you will see that it is really quite simple.) 

If the ridge on the rod or the indentation in the blade becomes worn, the damper blade may begin to spin freely on the rod, so that the damper handle no longer turns the blade properly. 

First remove the section of stove pipe and clean the pipe and the damper, to verify that this is the problem. Sometimes you will find that the ridge has simply slipped out, and you can push it back where it belongs. If it is worn, measure the diameter of the stove pipe, and buy a replacement damper at your local stove shop. 

Stuck damper

If the damper is stuck, chances are you have a buildup of creosote and soot in the pipe. Disconnect the section of stovepipe and clean it. It is probably time for a chimney cleaning, too… 

Door is too loose or too tight. Most door latches have adjustments on them. But if the door used to be okay and now seems too loose, first check the door gaskets. (See below) As gaskets become worn, the door will often feel loose. Since gaskets are the key to preventing air from leaking into the stove in the wrong place, replace them if they are worn, before you adjust the door latch. 

If the door is too tight, first make sure it is properly in place and in good shape. Check the hinge pins for wear (replace them if they are worn), and carefully check to see if the door has become warped. A slightly- warped door may be okay, as long as you can properly gasket it and adjust the latch so that there are no air leaks. But if the door is badly warped or damaged, replace it.

~ Todd Woofenden