# 4: I Have a Round Drop-down Trapdoor Style Damper. How do I Plug the Round Flue Pipe?

by blogediter | Aug 21, 2017 | Chimney Plugs, Fireplaces

# 4: I Have a Round Drop-down Trapdoor Style Damper. How do I Plug the Round Flue Pipe?

4-1 Open Flue Pipe above a Round Side-Hinged Damper

4-2 Closed Round Trap-door Side-Hinged Damper

4-3 9×9 Chimney Balloon installed in a Majestic Fireplace

Fireplace #4: Round Trapdoor Side-Hinged Damper Covering a Round Flue

This is the easiest of all the fireplaces to plug. The damper drops out of the way, and you get a clear shot at the round chimney flue. These sheet metal dampers are often fitted on Majestic or Superior brand zero-clearance pre-fabricated fireplaces. These were popular in the 70’s and early 80’s, and it is hard to get damper parts for them anymore. The sheet metal doors often warp, then the asbestos ring falls off the edge of the door. At that point they drop open on their own.

Wood Burning Fireplace Users:

Open the damper and make a diameter measurement of the hole just above the damper (image 4-1), then buy a Flueblocker that will fit in that hole. Or buy one that is a bit big for the hole, since you can then trim it down to fit with a sharp pair of scissors. Here are some examples:

Example 1: You measure 8” diameter = You buy a 9” Round Flueblocker

Example 2: You measure 9” diameter = You buy a 9” Round Flueblocker

Example 3: You measure a 11” diameter = You buy a 12” Round Flueblocker

Flueblockers are physically a little bit larger than their labeled size. This is so they can press in to fit and hold in place by pressure tension. When yours arrives you just press it right into place into the round chimney flue. It is up to you if you want to close the damper below the plug.

IMPORTANT! ESPECIALLY FOR FORGETFUL PEOPLE!:
If you close the damper below the Flueblocker, mark the fireplace VERY CLEARLY that the chimney is plugged. It is easy to forget about the Flueblocker up above the damper. You MUST open the damper AND remove the Flueblocker to use the fireplace.

Gas Log Users: If you have a gas log set in this fireplace, you have a decision to make.

Here are your two options:

You can turn off the gas line to this fireplace and put in a small 9×9 or 12×12 Chimney Balloon just above the damper. This way if you have a house guest that fires up the gas logs without asking, he won’t back up exhaust fumes into the house. The Chimney Balloon will burst and fall out since it is designed to do that. The downside to this, is the Chimney Balloon is an inflatable and not as durable as a Flueblocker.
You can turn off the gas line and remove or permanently disable the gas log set and then put in a Flueblocker. Do NOT light a fire under a Flueblocker. If you do light a fire under a Flueblocker fumes backup into the house and bad things happen…enough said.

Gas logs are a separate conversation. We also have an article on how gas logs can poison you or pick your pocket over time.

#3: I Have a Round Butterfly Damper with a Handle Attached. How Do I Plug the Round Chimney?

by blogediter | Aug 21, 2017 | Fireplaces

#3: I Have a Round Butterfly Damper with a Handle Attached. How Do I Plug the Round Chimney?How Do I Plug the Flue?

3-1 Open Round Butterfly Damper with Handle

3-2 Closed Round Damper with Handle

above the zero clearance fireplace damper

3-3 Flueblocker above Round Damper

Fireplace #3: Butterfly Damper in a Round Chimney with a Handle on the Face of the Damper

OK, so you have a butterfly damper with a hinged handle attached to it. Sometimes these are inset into the chimney a few inches (image 3-2). Sometimes they are right at the bottom of the chimney, and the chimney widens out to the firebox immediately below the damper (image 3-1). These sheet metal butterfly dampers pivot in the middle like a carburetor choke, and are often in bad shape, rusty and warped. After-all they are just made of sheet metal, and they are in a caustic and heated environment.

Wood Burning Fireplace Users:

Option 1: If you have space below your damper.
If you are lucky enough to have a small 1”or 2” vertical bit of chimney pipe sticking down below the closed damper before the pipe opens to the firebox (image 3-2). This is the perfect spot for a Round Flueblocker. You can tuck the Flueblocker against the face of the damper. But you will have to cut a slit in the edge of the wool pad for the damper handle to come down through.

Just make a diameter measurement of the hole below the damper (image 3-2), then buy a Flueblocker that will fit in that hole. Or buy one that is a bit big for the hole, since you can then trim it down to fit with a sharp pair of scissors. Here are some examples:

Example 1: You measure 8” diameter = You buy a 9” Round Flueblocker

Example 2: You measure 9” diameter = You buy a 9” Round Flueblocker

Example 3: You measure a 11” diameter = You buy a 12” Round Flueblocker.

Note: Flueblockers are physically a little bit larger than their labeled size. This is so they can press in to fit and hold in place by pressure tension.

Option 2: If you do not have space below your damper and it immediately opens to the firebox.

If there is no room below the damper (image 3-1), you will have to go with a Flueblocker ABOVE the damper (image 3-3) The wool pad is semi-rigid, so getting it up past the damper can take some pivoting and maneuvering. You may want an extra 6″ handle extender to make your handle longer.

Gas Log Users: If you have a gas log set in this fireplace, you have a decision to make.

Here are your two options:

You can turn off the gas line to this fireplace and put in a small 9×9 or 12×12 Chimney Balloon just above the damper. This way if a house guest come over and fires up the gas logs without asking, he won’t back up exhaust fumes into the house. The Chimney Balloon will burst and fall out, since it is designed to do that. The downside to this, is the Chimney Balloon is an inflatable and not as durable as a Flueblocker.
You can turn off the gas line and remove or fully disable the gas log set and then put in a Flueblocker. The Flueblocker does not burn away if you light a fire under it. If you do light a fire under a Flueblocker fumes will back up into the house. DO NOT do that!

#2: I Have a Circular Center Pivot Damper with No Handle. How Do I Plug the Round Flue Pipe?

by blogediter | Aug 18, 2017 | Fireplaces

#2: I Have a Circular Center Pivot Damper with No Handle. How Do I Plug the Round Flue Pipe?

2-1 Round butterfly damper

2-3 Where to Measure

round Flueblocker chimney plug installed

2-4 Flueblocker above the damper

round Flueblocker installed below the fireplace damper

2-5 Installed Below the Damper

Fireplace #2: Butterfly Damper with External Handle

The good news about this application is there is no damper hardware to fight with around the damper door. The damper handle is usually on the outside lintel face of the fireplace. Sometimes those handles don’t even work, because they get disconnected or rot out. But that doesn’t matter, because we don’t need them anyway!

Wood Burning Fireplace Users: Believe it or not, this application makes you very lucky. You will notice that there is a small 1”or 2” vertical bit of chimney pipe sticking down below the closed damper before the pipe opens to the firebox. This is the perfect spot to install a Round Flueblocker below the damper door (image 2-5). Or you can install the round Flueblocker above the damper (image 2-4).

Just make a diameter measurement of the hole below the damper (image 2-3), then buy a Flueblocker that will fit in that hole. Or buy one that is a bit big for the hole, since you can then trim it down to fit with a sharp pair of scissors. Here are some examples:
Example 1: You measure 8” diameter = You buy a 9” Round Flueblocker
Example 2: You measure 9” diameter = You buy a 9” Round Flueblocker
Example 3: You measure a 11” diameter = You buy a 12” Round Flu eblocker.

Note: Flueblockers are physically a little bit larger than their labeled size. This is so they can press in to fit and hold in place by pressure tension.

Gas Log Users: If you have a gas log in this fireplace, you have a decision to make. Here are your two options:

Option 1) You can turn off the gas line to this fireplace and put in a small 9×9 or 12×12 Chimney Balloon just above the damper. This way if someone fires up the gas logs without asking, they won’t back up exhaust fumes into the house. The Chimney Balloon will burst and fall out, since it is designed to sacrifice itself if introduced to flame. The downside to this, is the Chimney Balloon is an inflatable and not as durable as a Flueblocker so it will wear out after time. Also, you will have to install the Chimney Balloon above the open damper.

Option 2) You can turn off the gas line and remove or disable the gas log set and then put in a Flueblocker. The Flueblocker does not burn off if you light a fire under it. If you do light a fire under a Flueblocker fumes will back up into the house. So DO NOT light a fire under it.