The Fireplace Damper – Everything you need to know

Getting to grips with a working fireplace requires a sound understanding of the different parts of your fireplace and how they are used. Knowing the proper use of key fireplace components such as the fireplace damper means that you will enjoy being able to properly control and maintain your fire, save on energy and cash, as well as keeping an eye on your fireplace’s general upkeep.

The throat area of your fireplace, that sits above the firebox is a mystery to many homeowners but it is important to know how it functions. Much like a human throat, this area of the fireplace allows air to move from the chimney through to the fireplace and enables the hot combustion exhaust of your fire to escape up your chimney to your building’s exterior. The fireplace damper, which sits in the throat area of the chimney performs the important work of controlling airflow through the chimney. In this handy guide, we explore everything you need to know about the fireplace damper including its identification, use, and maintenance.


What is a fireplace damper?

This device is located just above the firebox of your fireplace. It enables your fireplace to be sealed shut when not in use. It is incredibly simple and is little more than a sheet of metal (cast iron or stainless steel) or ceramic seated within the flue on a spindle, which can be opened or closed by hand to allow the flow of air and smoke through your chimney. The damper is resistant to its exposure to fire and heat, as it needs to maintain its shape to properly occlude the chimney throat. Because the fireplace damper is not externally visible it may be easily overlooked, but if you start a fire and it is inadequately opened you may find yourself with a roomful of smoke. Your damper can be opened with either a chain, latch or handle, depending on the design of your fireplace.


Key benefits of a fireplace damper

It may not be the first thing on your mind when approaching your fireplace, but the damper is critical to the safe handling of your fireplace. A properly functioning damper carries the following benefits:

  • How To Use A Fireplace Damper GuideOne of the primary purposes of the damper is to let the smoke out of your firebox quickly, thus providing a key ventilatory function.
  • Your damper will keep cold air out. When you are not using your fire, if your damper is open, cold air will find its way down the chimney and into your living space. As the seasons’ transition, you may find your room with the fireplace feeling unseasonably cool and draughty. This most likely to be due to a damper that has been left open since the end of the last burning season.
  • A closed damper keeps more warm air inside your room. A household can lose a significant proportion of its heat through an open damper, up to 10 percent, meaning greater energy consumption and higher costs. Draught exclusion is a fast way of saving dollars on your heating bill, so you should close your damper as soon as it is safely possible after using your fire.
  • Enjoy greater control over your fire. You can vary the aperture made with your damper to control the amount of air your fire receives and therefore its intensity, from a roaring blaze to mellow embers. Leaving the damper fully open may mean that your fire burns out all too quickly. Closing it slightly slows down the consumption of fuel for a longer burn, with more heat retained in your property.

Key types of fireplace damper

Depending on the type and use of your fire, there are a variety of types of chimney damper doing the work of acting as a gateway between your home and the outside elements. Choosing the correct type of damper is critical to ensure that you have the correct closure in the throat of your chimney.

Types of damper include:

1) Top mount chimney damper

A chimney mount damper is positioned at the very top of the chimney and cap the chimney against heat loss or entry into the chimney flue of debris, leaves and animals or birds. Dampers at this position mean that the chimney maintains a temperature similar to room temperature, meaning that when a fire is started the chimney is already warm and able to effectively conduct smoke up and out of the building. The more contemporary models are made from metals like stainless steel or aluminum with a mesh guard around its edge, and may even possess a rubber gasket for a tight seal and to offset the effects of weathering. Chimney mount dampers are usually custom installed and are more expensive than the other types of dampers. They are controlled via a stainless steel cable which drops the full length of the chimney to a lever at the fireplace level.


2) Throat damper

A throat damper sits in the throat of your chimney and provides a seal to keep chilly draughts at bay. This is the traditional type of damper that is installed when a masonry fireplace is first built. For many old properties, this type of damper may be well worn and in need of replacement. It is a metal trap door that is simply opened or closed manually to allow your fire the ventilation it needs and to keep draughts out. These metal or ceramic plates may not create an optimal seal and corrosion or wearing may mean that they become draughty. Conversely rusting of the lever mechanism that opens and closes the damper may become stiff, preventing easy opening.


3) Inflatable dampers

These modern chimney dampers are a solution for chimney draughts that are not adequately dealt with by an existing damper. They are also known as chimney balloons, and as the name suggests they are inserted into the chimney flue and inflated to provide reliable occlusion that keeps cold air at bay. This type of damper is best suited to homes where the fireplace is not regularly used. It is made of a heat reactive material that disintegrates if in contact with heat so that it will not block the flue if it is accidentally left in place when a fire is kindled.


4) Custom fabricated dampers

A custom-made damper may be necessary if a chimney has an unusual shape size or performance requirement.


5) Automatic dampers

These dampers are typically used on gas fireplaces and automatically open when the fireplace is in use and close when the fire is switched off. Some are calibrated to adjust for certain temperatures and conditions and can shut off the fireplace if conditions are unsafe.


6) Gas fire dampers

The dampers used for wood-burning and gas fires are not the same. A well functioning throat damper for a wood-burning fire can be lethal if left in place over a gas fire. This is because if the flue is completely occluded a gas fire can generate poisonous carbon monoxide due to inefficient ventilation. This odorless, colorless and tasteless gas can silently kill do neglecting a damper can be fatal. For this reason, if a wood-burning fireplace is converted for a gas fire, the damper needs a damper stop which prevents complete closure at all times.


7) Flue dampers

A flue damper is typically a feature on a wood-burning stove. It is comprised of a piece of metal on a spindle that is externalized so the metal plate can be rotated to alter the opening of the flue. Flue dampers are typically used to prevent a strong up-draught or pull on a newly started fire. It can also increase heat output.




Fireplace damper opening mechanisms

In addition, you need to be able to identify the opening mechanism used to operate the damper properly. If you are in a new property it may not be readily apparent. Throat dampers are opened and closed using a variety of mechanisms which include:

  • How To Use A Fireplace Damper GuidePoker dampers (aka Banana Handle) possess an arched lever with tooth-like notches which will hold the damper in the desired position when the lever is raised and lowered into place.
  • Rotary dampers open and close by turning a screw-type rod which pushes the damper open and closed depending on whether the rod is turned clockwise or anticlockwise.
  • A double pivot damper works by pulling a notched handle which props the damper into the position you desire. Opening and closing with this damper handle mechanism may be difficult, especially if the component parts are old or worn.
  • Butterfly choke dampers operate on a chain system with one chain pulled to open and another to close or shut the damper. The chains are typically marked with a letter, O for ‘open’, C or S for ‘closed’ or ‘shut’.
  • For top-mounted chimney dampers, owners will probably have a stainless steel chain system that hangs by the fireplace. Pulling on a few inches of the chain will open or close the top-mounted damper as required and can be secured in the desired position.

How do I know if my damper is open or closed?

Before you attempt to start a fire you will need to know if your fireplace damper is open or closed. A roomful of smoke is bot the ideal way to find out that the damper is closed. Take the time to make yourself familiar with the signs that your damper is open. Usually simply looking or feeling is enough to assure yourself that your damper is in the position you require. Here are some ways in which you can tell the position of your damper.

1. Feeling for cold air. A vigorous draft is a sure sign you have an open damper. Place your hand inside the empty fireplace and feel for a cold draught or breeze, that is air traveling unimpeded, down the chimney.

2. Look inside the fireplace to make a visual check. Take a flashlight and put your head into the fireplace to look up into the chimney. If you can see straight up the flue then a throat damper is open. If you have a metal barrier overhead then that is your damper in the closed position.

3. If you have a chain or control you can check if it is in the open position. Turn rods, lift levers and pull chains, and then check for that reassuring draft.


How to use a fireplace damper

Once you have identified your damper you need to ensure that you put it to proper use when using your fireplace.

Before starting a fire you will need to ensure that your damper is open and your chimney is unobstructed to allow good airflow to your newly kindled fire. Using the opening mechanism, move the damper to the fully open position and keep the damper fully open until your fire is fully established, However, a fully open damper will cause a lot of the heat of your fire to be lost. To retain heat, adjust the damper so it is partially closed meaning more of the fire’s heat will stay in your home. When your fire is fully extinguished and cool the damper can then be fully closed. Do not close the damper before the fire is fully out as the live embers and ashes are able to generate carbon monoxide. Check for hotspots and stir the ashes to be absolutely sure. If your fire is left overnight you should keep the damper open, despite heat loss, to prevent a build-up of monoxide.

Also if you need added ventilation in the summer months the damper can be left open.




Using a damper in bad weather

In bad weather such as storms, rains, and hurricanes, the damper must be shut to prevent torrential rain entering your property as you would with windows and doors. A top mount chimney damper should be fully closed through bad weather. If you have a throat damper this should also be fully closed.


Troubleshooting damper problems.

If getting to grips with your damper is more difficult than expected you may have a problem with your damper. Throat dampers, in particular, are prone to wear and tear over time as heat, soot, and creosote take their toll. The cast iron from which the dampers are traditionally made can also corrode. Any defects in the damper or its function should be promptly addressed so you can continue to safely use your fireplace and keep out drafts when you need to. Do not neglect a poorly opening or closing damper as it can impede vital ventilation of your fire.


These are some key fireplace damper problems you need to be on the lookout for:

Drafting problems

Simply put this is an unacceptable backup of smoke and fire into your property. A plugged or closed damper is one of the most obvious causes. Consider this if once you start your fire, the smoke fails to dissipate. Even if slightly open the aperture may be inadequate, meaning the damper needs to be opened all the way. Even when open, a cold damper and chimney may cause the smoke to divert into your room. Warm the damper with a flame under the flue.


Creosote build-up

If you have neglected to adequately clean your fireplace you may be dealing with a build-up of thick, black and oily creosote around your fireplace which not only can cause the damper and its operating parts to jam but can be ignited if you start a fire. It could be burning creosote that produces the excess smoke rather than a closed damper. Your annual chimney inspection should deal with this problem.


Difficulties in starting a fire

A chimney cap and top mount chimney damper that will not open will prevent an adequate amount of air getting to your fire. If you are aware you have a top mount chimney damper, it will require inspection for proper functioning prior to the burning season.


A poorly opening damper

Always assess the opening of your damper before starting a fire. If you cannot open the damper, it may be jammed, broken or have a damaged opening mechanism. The metal components in the damper are susceptible to rust, corrosion, and build-ups of dust, soot, and creosote. Your first step is to seek a good clean for your chimney and see if this loosens up the damper system. A professional clean from a chimney sweep can also lubricate and reposition the moving parts so that they work smoothly and reliably. The handle assembly may be problematic. A handle and valve blade and chains can also become jammed or disengaged. Rotary dampers are particularly troublesome as the long screw-like handle can warp or corrode. All these problems require correction by an experienced chimney pro.

In very cold weather, the damper may well have frozen shut.


The damper is unable to close

A damper which cannot close will leady to draughts and loss of energy, It may be unable to seal shut because of warping or cracking in the damper over many years of use. A broken damper like this will need to be replaced. Depending on the design. the damper may also have become misaligned, dislodged, or the handle may have failed. In these cases, the professional remedy is very simple.


Can a fireplace damper be replaced?

Yes. Both the damper and the frame in which it sits within the throat of your chimney can be replaced. The cost depends on whether you are able to complete this job reliably yourself, or require the services of a chimney sweep. Even if you undertake a DIY job is important that you have your chimney inspected afterward by a competent professional. Replacing a faulty damper can be completed in a number of straightforward steps, but if you encounter unexpected problems do not hesitate to get help.

1) Clean your chimney. Before attempting removal of the existing damper, get into the fireplace and clean off the soot, dust and creosote build-up that is present. This will make the removal job much more simple.

2) A throat damper can be removed by unscrewing the nuts and bolts that hold it in place in the masonry. This may be made difficult if they have rusted and are difficult to release. Use WD-40 to loosen rusted bolts. Once the fixtures that secure the damper in place are removed, it can be dislodged and removed by way of your firebox.

3) Take the measurements of your damper for online ordering or take the whole damper to a retailer of chimney hardware to procure a suitable replacement of the right size. If your fireplace is exceptionally large you may need a custom damper to be made.

4) The replacement damper can be slid back into place in your chimney and secured with the nuts and rods you removed, provided they are in good condition. At this stage, you need to make sure that the damper is properly secured or you will encounter problems with its function. It should not be able to wiggle or fall.

5) Test your newly installed damper for proper opening and closing. It should be performing normally before you light a fire.


In conclusion

The fireplace damper is an essential component of a properly functioning chimney. It works as a valve to open or close access to the chimney from above or within the chimney’s throat. If you have a fireplace you need to familiarize yourself with the type of damper you have (whether top mounted or throat damper) and the means of opening and closing the damper effectively. Ensure that you open the damper fully whenever you are starting a fire and close it after use. Given the rigors of a working fireplace, you should ensure that your damper is inspected and cleaned regularly to ensure that it is working properly. Problems with venting of your fireplace or excessive draughtiness point to issues with the damper. Cleaning and inspection are good first steps for remedying any problems, but if concerned a professional chimney sweep had the experience and competence to make a proper repair or replacement of a defective damper.