Mechanical troubles with fireplaces: dampers

Sometimes it is the little problems that make a fireplace seem unusable. Here we will cover some common mechanical difficulties, and how to solve them.

Stuck or Non-Functional Dampers

Corrosion and debris are the most common causes of stuck dampers. 

A good first step is to have the fireplace professionally cleaned. Your chimney professional will sweep the flue and remove the soot and debris that is piled up around the damper. At the same time, he/she can lubricate the moving parts and make adjustments, or recommend a new damper if yours is damaged beyond repair. If it has been a year or more since you have had the flue cleaned, have it done, anyway, for fire safety

For the do-it-yourselfers, here are some hints for fixing dampers. But this doesn't take the place of a professional chimney cleaning. 

Safety Alert

Wear gloves and eye and ear protection any time you work on your fireplace. Damper edges are sharp, and will cut you. Debris in the flue could get into your eyes and ears, causing injury.

Fixing Throat Dampers

If your damper is a throat damper, the kind located just above the fireplace opening, it is operated either by a handle inside the fireplace, or by a small knob on the outside, somewhere between the mantel and the opening. 

Using a flashlight, take a look at the moving parts. If anything looks warped, rotten, or broken, call your chimney professional for a quote on a replacement damper. If the parts look rusty or corroded, first try oiling them. A spray penetrating oil works well. Put some newspaper down in the fireplace to catch run-off, and don't get any oil on the brickwork. 

Take a look at how the handle assembly works. Some are simply a notched handle that pushes the damper blade up. (The damper blade is the plate, the thing that actually opens and closes.) 

Others (among the external-knob type) have a worm-gear on a shaft. When you turn the knob, the shaft turns the worm gear. A ring moves along the worm gear, and pushes a lever connected to the damper blade. It sounds complicated, but take a look, and you will see it is pretty simple. 

A third type incorporates a handle and a counter-weight. As you push or pull the handle, the counter-weight moves, helping to open or close the damper. 

Yours might also be a variation on these basic types. Try pushing (gently!) against the damper blade. See if the damper blade's stuck, or if the handle mechanism seems to be the culprit. 

Safety Alert:  Watch out for falling debris!

You might find that there is a buildup of sand, soot, and debris behind the damper that is preventing the blade from moving. If so, have the chimney cleaned. 

Also, check along the bottom edge of the damper blade. Sometimes there are metal tabs or notches designed to fit into slots or holes in the housing. If the blade isn't set in place properly, that could be your problem. Sometimes it is necessary to disassemble the handle mechanism to get the blade back where it goes. 

It is probably wise to call a professional at this point, or you may end up with a pile of parts and no idea how to put them back – especially if you have the external-knob style of damper. If you decide to try it, be careful not to drop any pieces. Cast-iron parts break easily, and you could hurt yourself, too. 

Fixing top-sealing dampers

Adjusting a top-sealing damper requires getting up on the roof, a job best left to a chimney professional. Although top-sealing dampers tend to be relatively trouble-free, sometimes the cables need to be replaced or adjusted, or debris interferes with the moving parts. 

If you think the damper is frozen shut (during or after an ice storm), check with the operating instructions or the installer. Sometimes there is a feature built into the damper that allows you to tug sharply on the cord, engaging a lever-type device on the damper that breaks the ice seal. 

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