Should a Wood Stove Flue be Open or Closed?

All wood burning stoves will have a flue. And that flue can be controlled using the damper but should a wood stove flue be open or closed?

This is a common question for anyone new to using wood burners but in short, when the fire is on, the flue should be open. When it’s not on, it’s up to you.

What is a Flue?

Before we can talk about whether the flue should be open or closed, we first need to understand what a flue actually is.

This might sound slightly strange, but technically speaking, the flue is nothing but air. The flue is essentially the gap between the fire and the chimney. When your wood logs create smoke, the smoke will travel through the flue and out of your house.

Some may think, “A flue isn’t nothing; it’s a metal pipe”. But that’s not a flue. That is a flue pipe. The actual “flue” is the nothingness (or air) inside the tube.

This is a technicality, but since you’re here you may as well know it.

What is a Damper?

A damper is used to open and close the flue, and as a result control your fire, but what is it?

A damper is a small door that sits on top of the firebox, usually just above the flames. Most of them are made of metal, although it’s not unheard of to have a ceramic damper.

The purpose of the damper is to open and close the chimney.

When the damper is open, the air coming from the chimney can provide oxygen to the fire. But, when it’s closed, air cannot come in from outside, and the fire will die out much quicker.

Should a Wood Stove Flue be Open or Closed?

When the fire is on, the damper should be open. This is another way of saying that the flue should be open.

This will serve two key purposes in building and maintaining your stove fire.

Firstly, fire needs oxygen to continue burning. When the damper is open, air can travel from outside, down the flue pipe, and into the fire.

If the flue is closed, there won’t be enough oxygen to keep the fire going.

Secondly, the waste gasses need somewhere to escape. If the flue is closed, harmful gasses such as carbon monoxide can leak into your room and result in unpleasant smells, dirty air and potentially illness (with exposure over a long period of time).

This is why, before starting a fire, it’s essential to ensure the flue is open.

Should a Wood Stove Flue be Open or Closed when the Fire is Out?

Most people will not use their fires 24/7. Whether it’s too hot at certain points in the year, you prefer other heating methods, you’re on vacation or some other reason, there will be times when your stove remains unused.

We recommend having the flue closed when you are not using the fire. However, keeping it closed when the fire is not in use is not as important as keeping it open when it is.

Hot embers, just like fire, can create harmful gasses. When you close your flue, make sure all embers are completely dead. If you close your flue before the embers go out, the toxic gasses may enter the room.

You may choose to keep your flue open all year round. In the winter, you will most likely want it open because you have a fire burning. In the summer, you may want cool air to come through the flue pipe.

How to Open and Close a Flue?

Although each flue may be slightly different from the other, most of them will have a lever that enables you to open or close it at your leisure.

If you’re unsure to begin with, use a flashlight to check whether or not the flue is open.

Most of the time, when the handle is to the left, the flue is closed. And when the handle is to the right, it’s open. The damper shouldn’t be half-open- it must be either open or closed.

If you want to open it, move it to the right. Want to close it? Move it to the left. But, this is a rule of thumb, not a law, so make sure you know how to operate your flue damper in line with your stove manufacturer guidelines.

Flue and Damper Safety Tips

When dealing with fire, safety always needs to be a top priority. So, here are some tips to remember when dealing with a flue.

  • The damper is made of metal, and metal gets hot. Do not touch it unless you’re 100% certain the damper is cold. You could get anything from an unpleasant blister to second-degree burns if you touch hot metal. It’s better to be careful and make sure it’s cold before you grab it.
  • Wait for the fire to cool before you close the flue/damper. As we’ve already mentioned, if you close the flue before the fire cools down, any excess waste gasses will not be able to escape and will go into the room.
  • Open the flue before starting a fire. If you build a fire before opening the flue, the end result could be a room full of smoke and nasty gasses.
  • Be careful not to get your fingers caught. Just like with other doors, if your fingers get caught in the damper when you close it, that can be extremely painful. So just be careful where you put your digits.

Dampers Vs Vents: What’s the Difference?

Some people get dampers and vents confused. But, they are different.

Vents are located at the front of the firebox. Their primary purpose is to control flame size via increased or decreased oxygen levels. You can adjust them if you want a smaller or larger flame, as well as a fire that burns quickly or slowly.

The damper stops cold air from getting in when the fire is not in use. It is located at the bottom of the flue or the top of the firebox.

Once you’ve mastered a wood burning stove flue, you’ll never have to think of it again as the design and principle remains largely the same across brands and models.

We hope this helps, and for everything else home heating stick with