A guide to fireplaces (2023)

In addition to adding great character to a home, fireplace systems are essential if you want to enjoy the cozy benefits of a fireplace.Wood stove(opens in a new tab). This guide will tell you everything you need to know about fireplaces and flues and how to make sure your fireplace performs to its full potential.

Why do we have fireplaces?

Although holes in the roofs and walls of old houses are evidence that our ancestors knew it was important to get smoke out of their houses, chimneys were not widespread until Tudor times, and even then only among the Upper class, with most common people having to tolerate smoke filled rooms.

Even when fireplaces were used, they were highly inefficient and often dangerous, being made of adobe and mud and vulnerable to fire. In 1710 all earthen chimneys in England were instructed to be rebuilt in brick.

However, a misunderstanding of heat and smoke meant that chimneys still didn't work as they should, and it really wasn't until the mid-18th century that people like Benjamin Franklin (once nicknamed "The Universal Smoke Physician") Charles Willson Peale and Benjamin Thompson, later known as Count Rumford, vowed to make things better.

Earl Rumford invented a chimney and chimney to reduce smoke pollution in London. The new Rumford fireplace reflected heat towards the ceiling with the fireplace built into the wall.

How do fireplaces work?

Jonathan Green all forumsfornos Clearview(opens in a new tab)She says: “You can light a bad stove in a good fireplace, but not a good stove in a bad fireplace. It is even more important that a fireplace works properly. First you need to know what makes a fireplace do its job. In other words, why is the smoke going up the chimney and not leaving the room?

The upward movement of air and smoke in a chimney is called a chimney.blotter.The draft is due to the physical fact that hot gases are less dense than cold gases. Gases that are heated in a fireplace are lighter than air in the atmosphere and are therefore breathed in.

Logic suggests that a taller stack creates more draft simply because it contains more of the warmer, lighter gas, creating more updraft. However, the increased draft inherent in a taller stack tends to be offset by the increased friction in the stack and the tendency for gases to lose heat as they rise.

A very dirty chimney with a tall, thick chimney with poor insulation and possible air leaks may be less efficient than a shorter, well-designed chimney.

Another physical fact has an impact, albeit minor, on the performance of the fireplace. When air is blown into the end of a hose, there is a pressure drop across the end of the hose. First discovered almost 200 years ago by an Italian, GB Venturi, this principle is the principle by which most carburetors inject gasoline into the air stream. Wind blowing through the chimney has a similar effect, increasing draft.

For a fireplace to work well, it needs good airflow and the fireplace must maintain the highest possible temperature, which is why there are strict building codes for building fireplaces. For example, it is important to insulate chimneys as this will keep the smoke warm and less likely to condense as tar deposits. This is especially important with wood-burning appliances, as they burn cooler than coal.

Chimney terms explained

• Deduction:The cavity through which the products of combustion are vented to the atmosphere.
• fireplace insert:The material from which the draft in the chimney is formed.
• smoke pipe:A metal pipe used to connect an appliance to the chimney.
• Schornstein:A structure that surrounds one or more chimneys.
• Chimney connection:Another word for pot, hood, or other method of closing the top of the chimney.

types of smoke

The terms "chimney" and "chimney" are often confused. The chimney is the working section of the chimney that carries the products of combustion up and into the atmosphere, while the chimney is a structure built around a core of clay or concrete chimney liners and ending with a tray. (see the anatomy of a chimney below).

Fireplaces are divided into "classes".

• ANDclass 1Fireplaces are common in homes built up to the 1960s. They consist of a brick chimney located on an interior or exterior wall and containing multiple chimneys for multiple fires (although fires cannot share a common chimney). This type of fireplace can be used with all types of solid fuel fireplaces and stoves and also with gas fireplaces. They only need to be lined if they fail a smoke test.
• 2nd degreeExhaust systems (5 inches in diameter) are commonly found in homes built after the 1960s. They consist of an interlocking metal pipe that runs through the home, but can only be used with certain types of gas fireplaces. Class 2 (Precast) systems consist of a rectangular concrete or clay block void that extends through the wall void to a ridge vent or metal flue in the roof. Can be used with slimline gas fireplaces
• Balanced deductions:A balanced chimney exits through the back of a gas fireplace and receives combustion air from the outside and in turn expels the products of combustion through the same chimney.
• diversified deductionsThey are visually similar to an air/combustion gas extractor, but they extract combustion air from the environment in which they are installed. With electrical power, they can be placed away from an exterior wall. Both options are good options when there is no usable chimney.

fireplace materials

Both fireplaces and hearths are available in a variety of materials, including stainless steel, concrete, pumice, clay or ceramic, and plastic. Concrete, pumice, and clay or ceramic are collectively called "brick chimneys."

Plastic flues can only be used with low-temperature condensing appliances and some stainless steel fireplaces and chimney systems are designed for use with gas appliances only. However, clay and pumice fireplace systems are suitable for use with wood burning, multi-fuel, oil and gas appliances.

Factory-made chimney systems with pumice, clay, and ceramic can be retrofitted, but tend to be reserved for new construction, as they require a foundation and are best left to an experienced mason to build.

The anatomy of a chimney.

Uses:The following diagram shows a brick fireplace with a chimney. A chimney can actually contain more than one chimney, and its type is determined by the required heat-producing device. To open up an old chimney, the chimney must be cleaned and inspected by a professional chimney sweep and possibly relined to meet standards.

• FIREPLACE LINING:An approved refractory material lining the interior of theFireplace, usually made of refractory concrete or waterproof clay, but sometimes of metal. All chimneys should be built with a chimney liner to protect the masonry from flue gases, which liner also improves flow. It was not uncommon for old chimneys to be lined (lined) with lime mortar when the chimney was erected, but many were not lined. There are two types of linings: Class 1 (solid fuel) and Class 2 (gas).
• RAUCH:A vertical pipe or flue that provides a safe path for heat, smoke, and other combustion by-products away from the chimney. Located inside the fireplace. The chimneys must be high enough to guarantee a sufficient draft, in most cases around 4.5 m.
• EXHAUST CONNECTION:Connect chimney toFireplace. Curves must not exceed 45° to be swept.
• SMOKE CHAMBER:the square aboveperiod, where the smoke "accumulates" before merging with theFireplace.

• COMBUSTION AIR INLET:The fire must receive air from outside the house to burn the fuel safely; this input controls the amount of air supplied for combustion.
• FIREPLACE:A base that insulates a heat-producing device from people and combustible objects. The thickness of the stove depends on the device.
• FIRE BRICKS:Refractory brick masonry that forms the back and side walls of a fireplace. Refractory bricks are made of a ceramic material primarily built to withstand high temperatures.
• TO JOIN:A narrow opening between the chimney outlet andFireplace, onperiodusually raised to improve airflow and reduce pressuresmoke box.
• SMOKE BOX:A horizontal plane just behind itperioda chimney to avoid drafts. It also helps the chimney to get smoke up.Fireplace.
• PERIOD:Also called "neck". A rotating or sliding metal tab on theFireplacewhich regulates the air flow and prevents excessive fluctuations. You can also close the chimney from the outside of the house, preventing air leaks when the chimney is not in use. Sometimes it's on the device.

The meaning of the relationship.

For an open fireplace to function properly and for the fireplace to draw draft, the chimney to chimney relationship must be exactly correct. Chimneys over 6m in height should generally not be less than 1/7 to 1/8 of the area of ​​the chimney opening, for example a 225mm (9″) diameter chimney will support a chimney opening up to approximately 550 x 550 mm (22″ x 22″) (See Building Standards J 2.2.)

For bungalows, the ratio should be reduced to 1/6.

A great advantage of prefabricated chimneys and chimney systems is that the conditions have been carefully worked out, thus guaranteeing perfect operation.

If you're building a new fireplace, pay attention to what works for neighboring properties. They are already built or adapted to the local environment.

When placing siding, the connectors should be with the outer ends facing down. The idea is not to get all the smoke to rise, but rather that the water that comes out reaches the bottom, where it boils again.

How much will it cost?

Material costs for a new fireplace start atabout £1,000and, depending on the version, it can spiral up. However, there is usually a significant amount of work involved.

The budget option for a wood stove is a prefab stainless steel fireplace. While a gas appliance can use a single wall chimney, with solid fuel you should use an insulated double wall chimney to prevent smoke from condensing in the chimney. Typical material costs for a 7m long double-walled stainless steel cooker hood are approx.£ 1.300- £ 1.500. the main manufacturers arerite-ventilation(opens in a new tab),Poujoulat(opens in a new tab), miSFL(opens in a new tab).

Double-walled ceramic hoods are a more elegant option and are 30-50% more expensive than stainless steel. Ceramic impressions generally carry a 30-year warranty (instead of 10 years for stainless steel impressions). They are recommended for intensive use, especially withbelarus(opens in a new tab).

Precast pumice fireplaces offer a very easy way to build a durable, insulated masonry fireplace system at a cost similar to a double-walled stainless steel fireplace. Rather than having to purchase components from several different vendors, these fireplace systems are supplied as kits for easy assembly. Names to watch out for here are Isokern and Anki.

In short, chimneys require foundations while steel or ceramic chimneys do not. If you want a traditional pot, you'll need a chimney, since chimneys have finials. While fireplaces work with any type of construction, fireplaces work best with blocks.

maintenance

The number one cause of smoke entering a room from an existing chimney that used to be running is a clogged flue. The solution is to sweep the chimney. Inadequate airflow in the room can also cause blowback. Keep in mind that houses were traditionally very drafty, whereas today they are too cramped for a campfire.

If you don't provide enough oxygen to the fire, it will find its own, drawing large drafts up the chimney and spewing smoke into the room. Add a vent on an exterior wall next to your stove or fireplace, if necessary.

Rehabilitation of existing chimneys

Many people want to keep an existing fireplace and adapt it for use with a wood burning appliance. Check that the fireplace is functional and sufficient; a chimney sweep should be able to help here.

And it's common these days to install flexible chimney liners that normally slip into the existing chimney. While often not essential, a flexible fireplace insert will help free up the flow of smoke and make your fireplace more efficient.Expect to pay between £400 and £600 for flexible chimney liners plus the work to attach them.Keep in mind that it can take a lot more work to get an existing fireplace back into service.

gas fire

Most gas fireplaces can be installed as a gas water heater with a through-the-wall vent. You can also use electric fireplaces, which allow you to direct the exhaust greater distances with your elbows. This allows you to place a gas fireplace away from a suitable exterior wall.

Many thanks to Jonathon Greenall and Helen Davis of Clearview Stoves for their helpful fireplace tips.