What is the difference between a chimney and a flue?

Author: Hilma Runolfsdottir  |  Last update: Tuesday, November 11, 2025

A chimney is a passage way for combustion byproducts to travel up that runs from a fireplace or stove up to the top of a house. It is usually made of stone or brick. Inside the chimney is a flue. In most cases, a chimney flue is made up of a steel chimney liner or ceramic chimney tiles.

Are flue and chimney the same thing?

In general, the terms "flue" and "chimney flue" can be used interchangeably to some extent, but they are not completely synonymous. A flue refers to a duct or pipe that carries exhaust gases, while a chimney flue refers specifically to the pipe or duct within a chimney that is used to exhaust gases from combustion.

How do I know if my chimney has a flue?

A chimney contains a flue (some chimneys will contain more than one flue). > Flue - this is the space or cavity within the chimney which allows the smoke and gases from your fire to pass up, away from the fire, and out of your home. As you can see a chimney is the structure which contains the flue.

Do you need a flue if you have a chimney?

Although it isn't a requirement of the Building Regulations, it is the norm and definitely good practice to have a flue liner. Chimneys constructed prior to 1965 often lack a chimney lining and are in poor condition.

Can you have a flue without a chimney?

Yes. You can install a wood burning stove in properties without a chimney. Stovax has designed a twin-wall flue pipe system – the Stovax Professional XQ™ range – which allows rooms without chimneys to enjoy the benefits of a wood burning stove.

How Does a Chimney Flue Work?

What fires don't need a chimney or flue?

Balanced Flue Fires

If you are in the market for a gas fire but do not have a chimney or flue look no further than this balanced flue gas fire range. At Stoves Are Us, we offer a diverse range of balanced flue fires to meet every taste and requirement.

Should you open chimney flue all the way?

OPEN OR CLOSED? The damper should be kept closed when there is no fire or coals burning. Warm air from your home will not be lost up the chimney when the fireplace is not being used. Fully open the damper before your start a fire and keep it fully open until all embers and coals have burned out.

Do old chimneys have flues?

Clay tile flues are common in older homes and masonry chimneys. These flues have interlocking terra cotta tiles stacked vertically inside the chimney. Clay tiles are durable and can withstand high temperatures, making them suitable for different fuel types.

Can a house have a chimney but no fireplace?

Why A House Might Have A Chimney But No Fireplace. In some cases, the home in question had a fireplace at the beginning but was covered up when the owner renovated. Chimneys and fireplaces were typical in house buildings before the 1900s because the fire was the primary method to heat homes.

Does a brick chimney need a flue?

An unlined brick or block chimney should never be used to vent any type of heating appliance or fireplace. Some local jurisdictions do require certain types of flue liners as opposed to others. It is not uncommon to have building code officials require stainless steel flue liners for a chimney.

Where is the flue in a chimney?

Fireplace Flue Tiles: The vertical passageway up the inside of the chimney is the flue. The damper is often (mistakenly) called the flue, but the flue is the passageway. Clay flue tiles are the most common material used to line masonry chimneys when built.

How often should a chimney flue be replaced?

The average lifespan of a chimney flue liner is about 15 to 20 years. If you lived in your home 15 years or more you probably need to get the entire liner replaced to make sure it is up to code. If there is damage to your chimney flue liner your home is at risk for a serious home fire.

Does each fireplace have its own flue?

Each fireplace will have it's own separate flue which is divided by the mid feathers. The chimney breast in a lounge will usually house two flues; the lounge fireplace itself and also the bedroom fireplace directly above.

How many flues does a chimney have?

A flue is a venting system, each system needs its own so If you heat your home with oil or gas and have a fireplace you would have two flues. Often times they are in one chimney so if you were to look down the chimney it would be separated into two venting system inside one chimney.

How often should you clean your chimney?

The NFPA recommends that all chimneys be cleaned and inspected annually because if the system is compromised, it creates a fire hazard. It's best not to merely assume that a chimney system is in good working condition, no matter the circumstances.

What is the difference between a Class 1 and Class 2 chimney?

Class 1 chimneys are built to handle high temperature flue gas emissions making them suitable for powerful heating devices. Class 2 Chimney: A Class 2 chimney, on the other hand, is typically constructed using metal flues or prefabricated systems. These are commonly found in modern homes built post 1970s.

What is a fireplace with no chimney called?

Modern ventless fireplaces don't need any chimney or venting allowing you to have an indoor or outdoor fireplace in your house, apartment, or a condo without a chimney. These vent-free fireplaces provide a convenient, low-cost alternative to traditional fireplaces. They are easier to install and easier to maintain.

What is a false chimney?

Our CGMA quality assured GRP chimneys provide an excellent alternative to traditionally constructed stacks, offering speed of construction and extra floor space within the home. Offered in brick, stone and render finishes, using exactly the same material being supplied to the property.

How many chimneys does a house have?

In many cases, homes are just built with two separate chimneys instead of one with multiple flues. Alternatively, most areas require a separate chimney if you have heating sources on different floors (e.g. a wood stove on the ground level and a fireplace upstairs).

What is a flue vs chimney?

A chimney is a passage way for combustion byproducts to travel up that runs from a fireplace or stove up to the top of a house. It is usually made of stone or brick. Inside the chimney is a flue. In most cases, a chimney flue is made up of a steel chimney liner or ceramic chimney tiles.

Why does my old house have a chimney but no fireplace?

Chimneys with no fireplaces may have historical significance. They could be remnants of past heating systems that have been replaced or removed over time. These chimneys serve as reminders of the historical evolution of home heating methods. Other possible explanations include misinterpretation of external features.

What is the lifespan of a flue?

Stainless steel flue liners generally last for 15 to 20 years (though low quality liners may not even last for five). Good quality stainless steel chimney liners often come with a lifetime warranty.

Is a damper the same as a flue?

The damper and flue are two different parts, but they are related and involved in the same function. The flue is the inside tunnel of your chimney that brings gases from your fireplace out of your home, while the damper closes or opens the access to the flue.

Is it okay to leave the flue open overnight?

If you're leaving the home or retiring for the evening, always close the glass doors but leave the flue open.

How much heat is lost through an open chimney?

Warm air from your home naturally rises, and an open chimney provides an easy escape route. In fact, it's estimated that up to 30% of your home's heated air can be lost through an open chimney when the fire isn't in use.

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