How does the Flueblocker work?

The Flueblocker is made of a thick layer of wool felt that is rigid and dense. Purchase the size that is the same shape as your chimney flue, and 1″ or 2″ larger than the hole you are plugging. You tuck the Flueblocker into the hole and make sure the sides seal tightly against the chimney wall.

The insulation properties of the Herdwick wool in the Flueblocker make it dense and durable enough to seal and insulate at the same time.

For more info visit our How to use Flueblocker page.

Is it safe?

The Flueblocker is designed only to be used when your fireplace is dormant. Wool is naturally fire retardant and the handles are made of fire retardant plastic, so please don’t light a fire under the Flueblocker.

We provide warning markers with every Flueblocker so you can remind yourself the chimney is closed.

If you are concerned that someone may light a fire in your fireplace after the chimney is plugged, please use an inflatable Chimney Balloon to plug your flue. They are designed to collapse if exposed to heat.

Won't it get all sooty?

Yes it will. When you take out the Flueblocker have a bag handy to slide the Flueblocker into. You can transport it outside and shake it off.

The wool head can be washed on a wool cycle in the washing machine, but air dry it. If you tumble dry, it will shrink.

If it becomes too dirty to salvage, it can thrown out or composted, and a new head can be purchased.

Where do you put it when it's not in use?

Once removed the Flueblocker may have a sooty smell to it. So put it in a plastic bag and store it in the garage or shed. If you want to deodorize it a bit, you can sprinkle it with baking soda, or wash it.

What if I forget it's there and light a fire?

The Flueblocker is for dormant fireplaces. Do not light a fire under it! If you want to have a fire simply pull the Flueblocker out first, since it is reusable.

Remember, the person who puts the Flueblocker in place isn’t necessarily going to be the person who lights the fire. So put many indicators on your fireplace or wood stove that it is closed. We provide you a reminder dangle tag that is also a sticker, so you can post at least 2 reminders that your Flueblocker is installed.

If the worst comes to the worst and a fire is lit with the Flueblocker in place, the wool will smoulder and give off a bad smell. The fire will not draw properly, and the fumes and smoke will backup into the room. The handle and wool pad will be hot, so be careful if you attempt to remove the Flueblocker.

This is the reason it is advisable to keep a fire extinguisher handy if you have a fireplace or wood stove.

Do I need one for my woodburning stove?

Woodstoves often have butterfly dampers. These metal disc style dampers offer very poor sealing, so a Flueblocker can be tucked in below the damper into the flue pipe. Sometimes it is easier to access the flue pipe through the ash clean-out port.

Can I use it in my gas fireplace?

There are 3 styles of gas fireplaces: Vented gas log, non-vented gas log, and direct vent gas. According to building code the Flueblocker cannot be used in any of them if they are active units. You must disconnect or remove the gas unit from the fireplace to use a Flueblocker in the chimney.

What size Flueblocker should i get?

The Flueblocker comes in nine sizes. These sizes fit the vast majority of chimney flues, but not all. You can buy a Flueblocker that is slightly larger than you need, and then trim it down with scissors. Or you may have to cut a slit in the Flueblocker to accommodate obstructing damper hardware.

We do offer custom Flueblocker sizes if you call and let us know the measurements of your chimney. Our support line is 608-467-0229.

I ordered the wrong size. Can I change it?

We can appreciate that chimneys are hard to measure, and sometimes you need a different sized Flueblocker than what you ordered. However, It is much easier for us to exchange one that is not sooty from an attempted install.

If you have doubts about your measurements, do a test install with the plastic from the product packaging still wrapped around your Flueblocker. Size it up and see if it fits. This way if you need to exchange your Flueblocker for another size, it wont be all sooty.

If you are reading this after the fact, and you have already dirtied up your Flueblocker, give us a call at 608-467-0229. We will do our best to accommodate you.

Will the Flueblocker stop birds from nesting in my chimney?

No, The Flueblocker goes in near the bottom of the chimney, and birds nest at the top of the chimney. But the Flueblocker will stop the nesting debris and noise that birds send down the flue.

If you leave the Flueblocker in for a long period of time, be careful when removing it.  It could have a range of debris collected on it, and that would indicate a nest that needs to be cleared from the crown before using the chimney.

Will it cause problems with moisture buildup in the flue?

The wool is naturally breathable and will allow moisture to permeate through. If you have a problem with dampness in a chimney, it is usually a problem with the cap, crown, flashing or tuck-pointing of a chimney not routing precipitation properly.

You would be best served by calling a certified Chimney Expert to review your fireplace if you have dampness issues.

I have a chimney cap. Do I still need a Flueblocker?

Most simple chimney caps only function as a way to keep precipitation and pests from entering the chimney top. So using a Flueblocker with a simple chimney cap like this can help you control cold air, chimney odors, and bugs that the cap does not effectively stop.

Some chimney caps have a top damper function actuated by a cable or chain that allows you to close of the chimney at the top. These caps have a variety of brand names like: Lock-top, Lyemance, Energy Top, Seal Tight, Chim-a-lator, or Top Seal dampers. They do a great job of sealing a chimney at the top.

Unfortunately, tightly sealing a chimney at the top can have some unintended consequences. If the chimney is has creosote and soot deposits, the odor can start backing up into the house. Cleaning the chimney can often make this worse, since a chimney brush will stir up the ash and expose a fresh layer of creosote.

In the winter sometimes a top sealed chimney feels drafty. It is because the chimney acts as a big brick radiator sticking into the cold winter sky. The cold conducts through the bricks and cold air sinks. So the cold air rolls right down into the room.

A Flueblocker works well with a top seal damper, since it can be installed around the damper cable at the bottom near the firebox. It stops cold air and odors from entering the room.

How does a Flueblocker compare with a Chimney Balloon?

The Chimney Balloon is a good way of blocking a chimney as well. The up side is they are non-air permeable, you can buy them with very long handles for higher installs, and  they have a safety feature that reacts to heat if a fire is accidentally lit under them.

However, the Flueblocker is a more durable device because it is made of a thick wool pad, and it can install into tight vertical areas because of its minimal height.

They both do an excellent job of sealing and insulating a chimney flue.

My chimney throat is more than two feet above the fireplace- can I still use a Flueblocker?

Each Flueblocker comes with a handle and one extension rod, making the total length 1 foot. You can extend the length by adding one or two 6″ extension rods, making the total length 2ft. If you add any more rods it starts to get a bit wobbly, and it is difficult to get enough pressure to push the Flueblocker into the correct location.

Another option is to install a Chimney Balloon. They can be installed with extension handles up to 3 feet long.