How To Tell If A Damper Is Open Or Closed

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How can you tell if a fireplace damper is open or closed? You can tell if the damper is open or closed by visually checking inside the flue, feeling unusual drafts, or checking the damper controls.

Gas fireplaces use the same metal flue system as wood-burning fireplaces. The flue runs the chimney’s length and allows smoke and other exhaust gases from the fire below to exit the home.

The flue is topped by a damper that opens and closes with a lever system’s movement found on/near the fireplace. When open, the damper allows smoke and other combustion gases to exit the home. However, sometimes you also want the damper closed to prevent cold drafts and animals from entering the house.

Knowing how to check whether the damper is open or closed, therefore, is very important. During the warm weather, you need to keep the damper closed. But, as soon as the heating season sets in, you must check to ensure that the damper is open. Read on to learn how to determine whether your damper is open or closed.

What is a Chimney Damper?

The chimney damper is a device commonly found in wood and gas-burning fireplaces, designed to seal the furnace when you’re not using it. This way, it helps prevent conditioned (cool or warm) air from exiting the home when you’re not using the chimney.

You need to open the damper when you start a fire in the fireplace to allow for proper airflow and let the smoke out. Otherwise, there’s a severe risk of smoke and other harmful combustion gases filling the house.

How Does a Chimney Damper Work?

Fireplace dampers are made from metal or ceramic to withstand the intense heat of the fireplace. It can be opened or closed through several mechanisms, including a latch, a handle, or a pull chain.

The flap is located inside the chimney flue found inside the chimney. Although the damper’s primary use is to allow smoke out of the chimney or keep cold drafts out, depending on the position (open or closed), it also helps control the fire’s intensity.

By adjusting the amount the damper is open or closed, you effectively vary the amount of oxygen available to the fire. Oxygen is crucial to burning fires. Less oxygen means a smaller fire, while more oxygen generates a bigger, roaring fire.

What Type of Damper do You Have?

There are two broad categories of fireplace dampers – throat dampers and top-mount dampers. Here’s what you need to know about each;

Throat Dampers

A throat damper closes the base of your chimney and insulates the home from cold air. It’s built into the fireplace and can be seen at the top of the firebox.

The upper portion (throat) of the firebrick that lines the back of your fireplace should have a slight angle to guide smoke up and out while reducing air intake. It may also slant towards the throat damper. The throat damper swings to seal the throat shut when the fireplace isn’t in use.

Most throat dampers are made from iron or steel and are either black or rust-colored. You can easily reach into the fireplace opening and behind the lintel to touch the throat damper. It opens/closes with a knob located on the fireplace’s front or a special rod found above the firebox.

Top-Mount Damper

The top-mount damper seals the chimney cap, this closing the entire chimney flue. A key advantage of top-mount dampers over throat-mounted models is that it can also keep out animals and debris from entering the chimney flue.

A spring helps keep the top-mount damper open while the controlling handle is attached to the fireplace wall. You may also want to know that for top-mount dampers, the open position is the default. Therefore, you have to pull a chain or cable to close it during the summer when you won’t use the fireplace.

Fireplace Flue Open Position – How to Know It’s Open or Closed

Since, as we’ve mentioned, flues can create a pathway for cold drafts to enter the home and animals/debris to enter the chimney flue, knowing whether the damper is open and closing it when you’re not heating is critical.

Fortunately, it’s not very difficult to determine if your chimney flue damper is open. Consider the following three tricks;

Check Visually

This is really simple and one of the surest ways to check whether the damper is open or closed. Stick your head inside the fireplace and look up the flue. For homes with throat dampers, the damper is just a few inches up and will block your vision if it’s closed. You can even reach up and touch it to determine whether it’s open or closed.

For top-mount models, check for daylight at the top of the flue. If you can’t see the light at the other end, the damper is likely closed.

Can you Feel a Draft?

If the answer is yes, then the damper is likely to open. An open damper lets in cold air from outside the house via the flue. Move closer to the fireplace and even move your hand or face across the fireplace area. If the damper is open, you’ll feel a strong cold draft.

Check the Controls

Finally, you can determine whether the damper is open or closed by checking the damper controls’ current position. The controls vary. But, most chimney flue dampers use cable, rod, and handle controls. If you’re familiar with the on/off position of the controls, you should be able to tell, with ease, whether the damper is open or closed.

Chimney Damper FAQs

  • Push or Pull to Open Flue? It depends. For rod controls, you need to lift it (all the way) to open the damper. For top mount models, often, you need to pull a chain.
  • Where is the Damper on my Fireplace? It depends on whether it’s a throat-mount or top-mount damper. Throat mount dampers are built into the fireplace and visible at the top of the firebox. Top-mount dampers, meanwhile, seal the chimney cap.
  • How do you open a Damper? You can open a damper by lifting a rod, rotating a knob clockwise, or pulling a chain.
  • How do you open a Fireplace Flue with a Chain? There are two chains for throat dampers, one for opening the damper and the second for closing. All you need is to pull the right chain. For top-mount dampers, there’s a single chain inside the firebox. When the damper is closed, the chain is pulled in and placed on a hook. To open it, release the chain from the hook.

Now You Know

Remember, closing the chimney damper when you’re not using the fireplace is just as important as keeping it open during the heating season.