Chimney Damper Buyer's Guide
- Smoke back drafting into the home
Have you ever watched someone fumbling with a damper on a smoky fire? A fireplace damper acts as a gateway for the chimney, opening to let air pass through or remaining shut to keep the chimney sealed. They're a simple mechanism, but how do you know when they should be open or closed? And should they ever be left partially open?
Here's a guide to the different kinds of chimney dampers and how to operate the different styles. You'll also find tips on how to replace or install them.
What is a Fireplace Damper?
A fireplace damper is a simple flap that opens and closes inside the flue of your fireplace. When closed, it seals off the chimney so that warm air from your house doesn't escape. (No one enjoys paying to heat the outdoors.) When open, it allows the fire to vent properly and let the smoke go up the chimney.
- Prefabricated damper
Although there are different types of dampers, most are operated with a latch, handle, or pull-chain. They're made from fire-resistant material like steel, cast iron, or ceramic and sit inside or on top of the chimney.
Regardless of the type of damper, the basic purpose is the same. The ability to shut the damper and seal off the fireplace is much more energy-efficient. Without a damper, the chimney is a gaping hole sucking warm air (and heating dollars) out into the cold. The closed damper also protects from water and debris. Open dampers regulate oxygen to the fire and provide an exit for the smoke and exhaust from the fire.
Some damper models have only two positions: fully open or fully closed. However, most dampers allow you to adjust the opening so that the damper is partially closed. This gives more control over the fire because you can adjust the airflow and drafting. This extra degree of control increases the heat efficiency of traditional masonry fireplaces, which usually aren't very heat efficient.
Types Of Dampers
There are two main categories of dampers: throat dampers and top mount dampers. The throat dampers sit near the base of the chimney close to the top of the fireplace. Top mount dampers are mounted either outside on the top of the chimney or just inside the top of the chimney.
You also may come across names in the industry like poker damper, rotary damper, and pivot damper. These refer to the different types of controls by which the damper is opened and closed.
Poker dampers (sometimes called banana handles because of their shape) have a long, radiused metal piece with steps cast into it. This contoured handle pushes on the damper flap and the steps let you prop it up at different heights.
- Vestal poker-style damper control
A rotary damper uses a rotating worm gear to push open or close the damper. These usually operate with a "key" component on the outside of the fireplace that you can rotate to open or shut the damper.
- Vestal rotary-style damper control
Pivot dampers are similar to a poker damper, but the handle is jointed. To open the damper, lift up on the handle and push in. The handle slides along with a separate piece with grooves cut in it, allowing you to lock the damper in different positions.
Another type of pivot damper is a round damper plate that is attached to a control rod with handle and designed to be mounted within a stove pipe just above a wood burning stove. This type of damper is not often used on new stoves because they contain their own air control systems, but is necessary for older models that require a damper to be used in conjunction with the air controls on the stove to regulate the rate of burn.
For decades, the most common damper in masonry fireplaces was a cast-iron throat damper. This style consists of a cast-iron frame or throat mortared above the top of the firebox inside the smoke chamber with a cast-iron plate that pivots open or shut.
- Vestal 42-inch cast-iron throat style fireplace damper
The downside of these throat dampers is that they do not create a good air seal when the damper is closed. (This makes your home less heat efficient since it doesn't seal off cold drafts and lets warm air leak up the chimney.) It can also be difficult to find replacement damper plates for older dampers, due to the fact that damper plates sizes differ and aren't always branded.
A more effective damper option for masonry chimneys is the top mount damper. These mount at the top of the chimney and feature a silicone seal that makes them airtight when closed. They open with a weight or spring action and usually have a chain or cable to pull them shut. The chain or cable is routed down the flue and secured to a bracket inside the fireplace opening. These models are newer and are gaining popularity across the industry because they offer a much better seal.
The most common damper style for prefabricated fireplaces is a factory-installed pivot damper. In many cases, this is a round plate that is only slightly smaller than the inner diameter of the flue pipe. The plate pivots open and closed and is operated by a handle. The gap between the round plate and the flue pipe is small, so there is less air lost to the chimney than a masonry throat damper.
- Closing a prefab fireplace damper
There are also top mount dampers available for prefab fireplaces. Because prefab chimneys require a specific chimney cap, these dampers have a "drop-in" style that mounts inside the top of the chimney. The damper is not as airtight as a masonry top mount because it does not use a seal. However, it is very popular as a retrofit for masonry fireplaces that have been relined with a steel liner or prefabricated fireplaces that have a damaged or missing pivot damper.
- Lock-top energy saving chimney damper
Before Buying A Fireplace Damper
New prefabricated fireplaces should come with information about the type of damper they require, with many already including a factory pivot damper. When replacing old dampers, determine the type and position so you can find the matching replacement. Also, investigate any local codes and regulations for the use of dampers. Some areas restrict replacement or retrofit dampers depending on the type of fuel used.
Use a flashlight to look up the chimney or flue and examine the damper. If the existing damper is rusted, doesn't function, or doesn't seal, then you should consider repairing or replacing it.
Take note of the type of material the old damper is made out of (ceramic, steel, etc.) This can help you narrow down the best replacement. You'll also want to look for how it is operated and what mechanism (handle, rotary wheel, pull-chain) is used to open and close it.
- US Stove cast iron stove damper
If the damper sits right above the fireplace, it is a traditional throat damper. These are usually operated with a push/lift rod (poker damper) or some type of rotary control. If the damper sits on or near the top of the flue/chimney, then it is a top mount. These are often spring-loaded and default to an open position. They are operated using a pull-chain that hooks to the side of the fireplace.
If you wish to retrofit the fireplace with a different type of damper than the original or need assistance replacing an existing damper, consult with an NFI certified fireplace technician or reputable chimney sweep for guidance and installation.
- Gelco Manufacturing - In operation since 1979, Gelco Manufacturing established itself as an innovator in chimney services after introducing the first stainless steel chimney cap. Based in Aberdeen, North Carolina, Gelco produces durable, high-quality Lyemance and Lock-Top chimney dampers, designed to provide an exceptional seal and prevent the effects of backdraft.
- Vestal - Founded in 1946 after three brothers returned from the war, Vestal started as a steel fabrication and iron foundry plant in Sweetwater, Tennessee. The company extended its original product line of wood-burning heating, cooking appliances, and agricultural products to cast iron and steel products for residential house construction in the 1950s. Despite subsidizing under the Jim Walter Corporation and a later buyout, Vestal remains a leader in the industry, reputable as the world's largest producer of cast iron dampers and other essential fireplace parts and accessories.
- Lindemann - Priding itself on business ethics, honesty, and integrity, Lindemann places the customer first, always delivering the best chimney service products. Lindemann has an extensive product line, including liners and pipes, chimney caps, dampers, and fans, chimney sweep equipment and tools, masonry supplies and repair, and hearth and fireplace products.
- Bernard Dalsin Manufacturing Company - Conceptually birthed in 1969 after the founder decided to split his commercial roofing company of 25 years into two separate businesses. BDM began paving the way for a new product line, CHIM-A-LATOR. With a focus on quality, Mr. Dalsin centered the mission for the new line on performance reliability and economic value, establishing its current position as a leader in the industry for fireplace products.
How To Use A Fireplace Damper
Many people wonder about how to properly use a chimney damper. Opening the damper is straightforward: always make sure the damper is fully open before lighting a fire in the fireplace. This allows the chimney to draft at maximum efficiency during startup and effectively remove smoke. Closing the damper is more complicated. You want to leave it open long enough for the initial startup smoke to escape, but not so long that you sacrifice heating ability. This also only applies to masonry fireplaces with adjustable throat dampers. Prefabricated fireplaces and top mount dampers do not have the ability for variable adjustment.
Wood burning stove pivot dampers also should be fully opened when first lighting the fire. Once the kindling fire is burning and the first fuel logs are burning well, the damper can be slowly closed to regulate the fire and gain a longer burn. Operating a pivot damper in conjunction with the air controls on a stove is an art and requires practice to find the balance between efficiency and accidently choking out the fire.
Never close the damper completely while the fire is still burning. You want to make sure smoke and dangerous carbon monoxide don't flow into your home instead of out the chimney. If you have a wood burning fireplace that has been converted to gas, wait for approximately 30 minutes after turning off the flames to make sure the fumes have cleared and the damper has cooled before shutting it. Wood fireplaces take much longer since you need to wait until there are no more smoldering embers.
This is a good time to point out that carbon monoxide detectors are an absolute necessity for safety with fires. If fires are improperly vented, they can spill carbon monoxide which is harmful and even deadly into the home. Carbon monoxide is odorless and colorless, so by the time you notice something is wrong, it is often too late. Carbon monoxide (CO) detectors alert you to the danger so you know if there is ever an issue with the venting.
Some dampers are adjustable so you can have them partially closed. This is one way you can control the amount of airflow and adjust the burn rate of the fire. Keep in mind, however, that partially closing the damper increases the risk of getting smoke and carbon monoxide in your home. Always monitor the fire closely and ensure the fire is still able to vent and get oxygen.
- Operating cast-iron throat damper
If you want to adjust the damper, start with the damper fully open and light your fire. After the fire has burned for a little while, slowly adjust the damper so that it is partly closed. Do this in small increments. The flames may die down, but watch to make sure that the fire is not getting too smoky. The goal is to achieve a slower burn with smaller flames that don't produce too much smoke. This slower burn is a more efficient fire that uses less fuel and can help keep the room warmer by reducing the draft. If you start to get more smoke, open the damper back up again. Rotary dampers can easily be adjusted during the burn, but a damper tool or hearth glove is needed to adjust a poker damper and prevent burns.
Wood burning fireplaces that have been converted to gas do not require as much damper maneuvering to control the intensity of the fire. Instead, the damper is used mainly to control the stability of the flames, direct flue gases up the chimney, and maximize heat output.
Poker dampers have a contoured handle or rod located either inside the fireplace. To open the damper, lift up on the handle to free it from the retaining bracket and push upward. You can then lock the damper in its new position by setting it down into a different notch.
Pivot dampers are similar to poker dampers, but the handle has a hinge in it. These dampers typically default to a fully open position when unlatched. It is important to leave these dampers fully open during operation because they do not utilize adjustment steps and can accidentally fall closed during operation.
Rotary dampers often have a rotating knob or key on the outside of the fireplace. Spinning this knob operates a gear that pushes or pulls on the damper depending on the direction that you are turning. This opens and shuts the damper. If you are unsure of the damper's position, you can shine a flashlight to watch the movement of the screw while you twist the key or knob.
How To Install Or Replace A Chimney Damper
Masonry fireplaces usually have a throat damper with a cast-iron plate. The plate itself is simple to replace as long as you can find a matching piece. If the throat piece itself is damaged, consider installing a top mount. Prefabricated fireplaces rarely need replacement dampers, but there are solutions if necessary.
- Chim-A-Lator top mount damper
Over time, the plate on masonry fireplace dampers can warp, which increases the amount of air that escapes when the damper is closed. The plates are easily removed and replaced, but the problem is finding one that fits. There are many different sizes and manufacturers of damper plates, so it may be difficult to find a match (especially if the fireplace is old.)
Top mount dampers are more expensive, but they are a definite upgrade for masonry fireplaces. The design offers a far better seal, so you won't be losing warm air up the chimney. You may decide it's better to skip repairing the throat damper and move straight to the top mount. Just make sure the old pieces of the throat damper don't interfere with the operation of the new damper. (It may be best to remove the plate if you install a new top mount damper.)
If the throat piece itself (not just the cast iron plate) is rusted or damaged, the repair is extensive. We recommend hiring a professional since improperly removing the old throat could damage or collapse the fireplace.
Many prefabricated fireplaces have the damper plate screwed to the pivot rod or held in place by pins. These can be removed and replaced as needed. Some damper plates are welded in position and cannot be replaced.
As mentioned above, it's very rare for a prefab fireplace to need a replacement damper. If you do and the damper plate is welded, you can opt for a drop-in top mount. This version of the top mount isn't necessarily an upgrade, but it will substitute for a broken welded damper. Both the prefab throat damper and the drop-in damper have similar properties. They are not completely airtight but do offer good protection against drafts.
Top mount dampers are worth fixing if they just need a replacement spring, cable, pivot arm, or spring arms. If the base or lid is damaged, we recommend replacing the whole thing.
Chimney dampers are shipped by small parcel carriers like USPS, UPS, or FedEx. Check the package when it arrives to make sure nothing is missing or damaged. If you notice damage, contact the manufacturer immediately. Warranties are often time-sensitive, so the sooner you report any issues, the better!
Care and Maintenance
Not surprisingly, the lifespan of fireplace dampers is directly related to how often the fireplace is used and how hot the fire gets. Chimney caps also help protect dampers from moisture and debris, which keeps them in better condition. At least once every burning season, inspect the damper to make sure all the parts are in good working order.
- Holding a flashlight
To inspect a throat damper, wait until the fireplace is completely cool and then use a flashlight to look at the damper. Check for rust or warping. Test the handle or other components and make sure the damper responds properly. Use a similar process to test the operation of top mount dampers.
Chimney dampers are the lids that open to let the smoke out and closes to keep the heat in. Knowing how to properly time the opening and closing of the damper is part of ensuring a safe and efficient fire. Be ready for burn season by making sure your damper is intact and working properly.
If you have any questions about chimney dampers, reach out to one of our NFI Certified Specialists. We are happy to help!
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Chimney Dampers Q&A with the NFI Certified Specialists* Please Note: All customer questions are answered by our NFI Certified Specialists free of charge!
14 Questions &
from San Pedro, CA asked:
February 19, 2020
I am looking for the damper lid for a house built in 1929 and just need the lid. It was a chain pull style with notches at the two ends for a "lay in" cast iron lid that pivots using the lid's end pegs. My lid opening (without the flange measurement on which it sits - about one inch wide - is: 6" x 20 1/2". Can this still be bought?
Unfortunately, we do not offer any replacement damper plates outside of the Vestal products we offer. Since none of the Vestal damper assemblies operate in this fashion, the plates wouldn't work.
on February 19, 2020
from Lake Forest, CA asked:
January 16, 2020
My gas fireplace has a manual damper that requires me to lay down and reach into the fireplace. Are there any automatic solutions?
We do not sell any automatic dampers for gas fireplaces. We apologize for the inconvenience.
Tyler M. - NFI Master Hearth Professional
on January 17, 2020
from Canton, OH asked:
December 31, 2019
Seeking a bimetallic thermo movement air/heat vent for my Superior gas fireplace. Do they make replacement bimetallic hinges?
We do not offer any such parts for gas vent pipe. We apologize for the inconvenience.
Tyler M. - NFI Master Hearth Professional
on December 31, 2019
from East Hampton, NY asked:
December 6, 2019
Do you sell a conversion kit for a wood stove into a normal fireplace damper?
With most old wood stoves, a connector and/or adaptor such as you describe needs to be custom-made, usually fabricated locally.
Tyler M. - NFI Master Hearth Professional
on December 6, 2019
from Bowie, MD asked:
November 22, 2019
Is there an electric, remote or manual [external] damper for a fireplace with a wood burning insert?
We apologize, but we do not have a damper that is listed for use in conjunction with a woodburning fireplace insert.
Tyler M. - NFI Master Hearth Professional
on November 22, 2019
from Pittsburgh, PA asked:
November 18, 2019
Looking for a damper plate for a 24in x4in 1922 Majestic Damper. It has a handle on the side.
We apologize, but we do not have a part that will work for your application.
Tyler M. - NFI Master Hearth Professional
on November 20, 2019
from Bryson City, NC asked:
October 12, 2019
Is there a top-mounted damper that works with a zero clearance flue pipe that seals the flue as well as the vented air space around the inside flue pipe?
There isn't because the space between the inner and outer pipe must remain open with any air cooled chimney system.
on October 14, 2019
from 27403 asked:
March 18, 2019
I am looking to replace my fireplace damper. My current damper measures 5 inches wide and most of the ones I have found online are 7 inches. Any suggestions? Can I use a 7 inch one or do I need to keep looking for 5-inch?
A 7" damper plate likely wouldn't work because it wouldn't have the properly sized hinges to hang onto your space.
on March 19, 2019
from Seattle, WA asked:
March 12, 2019
What top chimney dampers will work with the following flue measurement:
Outside 17" x 8 5/8"
Inside. 15" x 6 5/8"
from Lake Forest, CA asked:
February 28, 2019
I have a 10 x 13 inch OD oval shaped flue on my woodburning fireplace chimney. I would like to put a chimney top damper on it to prevent cold air from entering my home. Do you have such a device?
from Bozeman, MT asked:
January 27, 2018
Are there any electric dampers for gas logs designed with shielded wiring harnesses that can be ran through the chimney pipe instead of trying to feed wire through walls, etc?
We are not aware of any product matching this description. If you are installing vented gas logs in a masonry or prefabricated wood burning fireplace, you should remove or affix the damper open and not use any top-sealing damper system of any kind.
on January 29, 2018
from Chicago IL asked:
January 1, 2018
I read that a lock top damper should not be used in gas log fireplaces. Why? Is that a requirement or a recommendation?
This is because a damper should never be used with a gas log set, as the house will fill with carbon monoxide if the set is turned on but the damper is accidentally left shut. All vented log sets come with a damper clamp to make sure that any operational damper is left open at all times.
on January 2, 2018
from kensington, NH asked:
November 8, 2016
We have a missing damper plate in our fireplace. The actual opening measures 28 and 13/16" x 5 3/4". I assume we'd need something a bit longer on both measures, right? Do you have a replacement plate that might fit?
from Philadelphia, PA asked:
August 19, 2014
How do you determine what size damper you need? Can a novice replace the handle?
The damper throat should be sized to the width of the fireplace opening. If the opening is sized between the castings available, it should be sized to the closest casting step. The handle itself is usually simple to replace. Most models simply have a drive pin holding the handle in place, but it differs from design to design.
on August 19, 2014