Chimney Dampers, a hidden helper

Chimneys appear to be simple structures comprising a hearth on the inside of a building and a stack visible from the outside, but they are made up of several parts one of which is a chimney damper. In this article, we look at chimney dampers, what they are and why their correct use is important.

What is a chimney damper?

Chimney Dampers

A chimney damper is a plate of metal, often made of cast iron, steel or other heat-proof material, that can be pulled up or down to open or close the flue. Opening and closing the chimney damper controls the airflow, regulating the draught. When a fire is lit, the damper must always be open to allow gases to escape. It can be closed when the fire is not in use to prevent heat loss from the room and to prevent cold air from blowing down the flue.

It is a good idea to think of your chimney as an appliance. It is there as part of the heating system of your home. When used as an open fire to burn wood or solid fuel, a good burn is achieved through the power of the draught.  The draught is also most important to ensure the gases created during burning are taken up the flue and expelled out. However, most chimneys, especially domestic chimneys, are not lit all the time. A consequence of this can be a cold draft blowing down the flue and into the room. This is where a chimney damper comes into use.

Where is the chimney damper?

There are two positions in a chimney where you might find the damper. The most common is in the throat, which is a position just above the firebox, or where burning takes place. They are close enough to the hearth, or fireplace to be seen by looking up the chimney. The damper is open if, when looking up the chimney, the flue is visible.

The other type of chimney damper is a top-sealing damper, sometimes known as a chimney cap damper or top-mounted damper. As you would think, these are located at the top of the chimney stack. They have the same function as one located at the throat, regulating the airflow. A top-sealing damper has a rubber seal making it airtight, so it also has the benefit of preventing rain, wildlife, and debris from entering the chimney.

How do they work?

Both types of damper are opened and closed manually with a mechanism in or close to the fireplace. Throat dampers are operated with a handle. These vary from a ‘saw’ style or a poker type which attaches to the damper and are either pushed or pulled. Alternatively, there are rotary-style handles that are turned as you would a key to open or close the damper. With a top-sealing damper, the mechanism to open and close the damper is by a handle, usually at the side of the firebox. The handle is attached to a steel cable that reaches up the flue to the damper.

The position of the chimney damper should always be checked before lighting the fire. It is important that the damper is fully opened before starting the fire otherwise smoke and gases will be expelled into the room. Burning wood and solid fuels creates carbon monoxide, a poisonous gas, so it is imperative that the damper is open and the chimney is in good order when using a fireplace. Any closed, or partially closed damper will restrict the flow of these gases and can be injurious to health. You can read our article for more information about Carbon Monoxide.

What type of chimney damper should I have fitted?

If you have a chimney, you will already have a damper as they are part of a chimney’s construction, and it is likely to be a throat damper. If there are issues with the damper, then you could choose to replace it with a top-sealing damper.

Pros and cons of throat and top-sealing chimney dampers

Throat damper


  • Easy to use
  • Easy to control
  • Helps retain heat in the room


  • Metal on metal, so not a full seal
  • Can warp over time
  • Can rust over time

Top-sealing damper


  • Airtight
  • Energy efficient
  • Keeps rain, debris and wildlife out


  • Can only be fitted on masonry chimneys
  • Can only be fitted on open fireplaces
  • Access is via the roof only


Do I need a damper for my wood-burning stove?

Modern wood-burning stoves do not usually need a damper because they are designed to be efficient in expelling the gases of combustion. Older models may well have a damper to help to control the airflow. These would be in the stove pipe. Where there is no damper, some older models may benefit from having a damper fitted. If your wood-burning stove is not working to capacity and you are having issues, then it is a good idea to have the stove inspected.

Billing Chimneys has years of experience in wood-burning stove installation and can help you achieve optimum efficiency in your stove. Our expert engineers will be able to tell you if a damper would help or if there is something else that is interfering with the system.

Cleaning and maintenance of a chimney damper

As with everything associated with a chimney, keeping the chimney damper clean and well-maintained is essential for it to work safely and efficiently. It goes without saying that the fire must be out and the firebox completely cold before attempting to do any cleaning inside.

It is possible to remove, clean, and replace the damper plate if it’s a throat damper. There are nuts that when undone will allow for the rod to be removed and the plate lifted out. If it’s cast iron, it’s likely to be heavy, so care must be taken. When it’s out, check it for warping and rust. The plate can then be cleaned by brushing to remove soot and any creosote burned onto the damper.

With top-sealing dampers, because they are made of steel, rusting is unlikely. The cable may need replacing or debris removed from on top of the plate. However, maintaining a top-sealing damper will need access to the roof and is best left to professionals like Billing Chimneys.

Whatever you choose to do, cleaning and maintaining your chimney damper is a messy job, so why not call in the professionals? Billing Chimneys offers a full range of maintenance and repair services carried out by experienced and friendly engineers.

Your chimney damper is an important part of your chimney’s system and ensuring it is in good working order will provide your home with warmth alongside optimum energy efficiency. If you have any questions or concerns about your chimney damper, give us a call.

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