How Hot Does A Chimney Flue Get?

The flue and chimney are two parts of a fireplace that people don’t typically pay all that much attention to. But that doesn’t mean they’re not important. The firebox obviously reaches high temperatures, and precautions measures are taken, but how hot will the chimney flue get?

A chimney flue can get up to and over 1000°F, with the average operating temperature being between 300° and 480°F. If it is over 1000°F you might be dealing with or are close to a chimney fire.

The temperatures that the flue will reach can vary widely. Usually, high temperatures are not that big of an issue, but your flue can get too hot. How do you even check the temperature of a chimney flue? We cover all that and more in this article, read on to find out!

How Hot Does A Chimney Flue Get?

Your chimney flue temperature will vary, but a chimney flue can get as hot as 1000°F, if it exceeds this temperature then you likely have a chimney fire on your hands.

You must wonder just how hot it gets inside the flue/chimney when you have a fire roaring in the fireplace. There are many fireplace enthusiasts that monitor how efficient their stove is, and whether it is producing adequate heat to warm their homes or not. With that in mind, let’s look at just how hot it gets in there.

Your chimney flue will normally sit within the range of 300-480°F, unless you are adding a lot more fuel to the fire than is necessary. This would then cause the temperatures to be much higher which increases your risk of having a chimney fire and damaging your flue/chimney in the process.

When the temperature drops below the 300°F mark, this is when creosote starts to form on the inside of your flue. It is recommended to maintain the temperature of your stove above that mark to prevent creosote from forming and to ensure you are getting enough heat from your fireplace to heat your home.

Depending on the efficiency of your fireplace and flue/chimney set up, you may burn at a higher temperature than is given above to heat your home, and that is okay.

When you start to exceed 800°F consistently, you will want to consider having a technician look at your setup and see if replacing it makes more sense. When you need to burn that much fuel to keep a consistent temperature, there is a lot of heat loss happening that is making your fireplace very inefficient.

Creosote’s (the substance that builds up on the lining of the flue from smoke build-up) flashpoint is only 165°F, which means that any spark or flame that it comes into contact with will cause it to ignite. When the temperatures are much higher, creosote will change from a tar/solid substance to a liquid and drip down the flue into the fire.

We mention the creosote build-up because it is the main cause of all chimney fires and want to help you prevent any disasters if possible!

How To Check Your Flue’s Temperature

On a single wall stove pipe (flue), attach a magnetic stove pipe thermometer approximately 18” from the back of your fireplace. On a double wall stove pipe, you will need to use a probe-style thermometer and have it set to the very middle of the piping for an accurate temperature.

When you purchase a stove pipe thermometer, the instructions will show you how and where to install it on your stove pipe.

  • For a single wall (class A), you simply need to attach it at the 18” mark from your fireplace and it will give you an accurate reading.
  • On a double wall pipe (class B), you will need to get a probe style thermometer. Follow the instructions on the package, but it should be set up in the same location as the single wall thermometer.

Many fireplaces will come with a thermometer that will allow you to monitor its efficiency from day one. There are also a large variety of thermometer brands to pick from that are all highly rated.

Here are a few options that you could use:

  • Midwest Hearth Wood Stove Thermometer (Single Wall)
  • Galafire Magnetic Stove Thermometer (Single Wall)
  • Condar Fluegard Stove Thermometer (Double Wall)

These are all highly rated thermometers that are cheap to get off of amazon! These will help you monitor how hot your stove is and recognize when things are getting too hot!

Can I Put Anything Near The Flue?

You need to have 36” of clearance from the flue in all directions for it to be considered legal. So long as anything you are looking to hang or place near the flue is at least that far away you are safe to put it there.

Your fireplace or wood stove is required to have a stone, brick, or tile material surrounding any area within 36” of it. This goes for the flue as well since it too can get to dangerously hot temperatures.

If you are considering hanging artwork or some sort of decorative piece near your flue, consider whether it will be affected by the heat being released. Heating up the paint may lead to damages.

The tiling that is installed around a fireplace is often beautiful on its own, and if we had to make a recommendation, don’t place anything that isn’t related to the fireplace near the flue.

What Is A Chimney Flue?

A chimney flue is the inner barrier that protects the chimney from heat and corrosion. It is usually made up of steel, clay, or ceramic; it contains the combustible products and directs them outside.

The flue will vary depending on the type of fireplace that you have, whether you have a wood stove, masonry, or gas fireplace installed.

The flue on a woodstove is the round metal piping that you see coming out the top of it, and directed out the side or roof of your house. The flue on the other styles is made of a similar material, but it lines the inside of the chimney that directs the chemicals and smoke out the top of the building.

The most common flues we see now in modern homes are made from steel,. You can always check with your local building code to determine what kind of flue your home needs to have in it.

What’s The Difference Between A Chimney And A Flue?

A chimney is the vertical channel that directs smoke and combustion gasses from your fireplace; the flue is the inner sleeve, a conduit that is installed on the inside of your chimney that protects it from being damaged.

A chimney is a large structure that exhaust all the fumes from your fireplace. But inside the chimney, you can find the flue. One chimney can have multiple flues for multiple different fireplaces or appliances.

Dan Westfield

Hi everyone! My name is Dan and I currently have two fireplaces, a wood-burning and a gas one. I cannot live without them and love to share my passion with you all!

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