Chimney - a vertical pipe or channel, rectangular or circular cross-section, which is used for removal of smoke or the combustion products from the appliances and devices for heating, cooking, heating water.
Practice flues use shows that for normal operation they should have insulation. Sometimes it is possible to insulate the pipe as a chimney stove with his own hands.
The most commonly furnace flues or chimneys are prepared using the masonry, as well as metal or asbestos cement pipes of suitable diameter. To prevent fire from inadvertently slip through the flue duct spark, a top mark (headroom) is raised above the surface of the roof at a height of not less than one meter.
Why do chimneys need insulation
So, for normal continuous operation the smoke channels must be insulated from the surrounding space. Why insulate the chimney, it is a necessity?
In operation, to which is attached the flue, the temperature difference between the inner and the outer surface may be tens or hundreds of degrees Celsius. This causes formation of condensed water, which when mixed with the escaping combustion products constitutes aggressive acidic or alkaline substances adversely affecting the flue structure channel.
The inner surface of the flue duct without insulation is covered with thick resinous sediments hindering its regular cleaning and affect the strength characteristics of the material from which is made chimney.
For example, brickwork starts as a result of erosion is rapidly destroyed from the outside and the inside, the same applies to asbestos-cement pipes. The metal structures emerge and rapidly evolving corrosive phenomenon.
To prevent the emergence and development of such defects are the most effective measures to ensure the shifting of the condensation space (dew point) for the outer limits of the structure. This contributes to tying chimney insulation, especially in those places where it passes through the non-insulated loft and rises above the roof in contact with the outer atmospheric air.
Materials and methods of thermal insulation of the most common types of flues
The main requirement, which should have a heater used for chimneys, is that it should be non-combustible and in any condition does not sustain combustion. With its high insulating properties, in operation the material must not modify its properties, be subject to shrink phenomena associated with a decrease in volume and formation of unfilled voids and cavities. Thermal insulation can be:
- in the form of compressed fiber mats, capable of passage around around the tubular structures with a circular or rectangular cross-section small area;
- granular, fine sand as a medium or a large fraction, of many ways resulting solid porous refractory material,
Thus, as heat protection material is a flexible plate or mat of mineral wool from basalt, or expanded clay, perlite, vermiculite or sand mixtures, and in some cases ground foam or aerated.
The most popular types of fume collection channels include:
- brick;
- asbestos;
- metal.
brick chimneys type most often used for heating furnaces and devices, which include some types of fireplaces. Offtakes permeate their entire structure and for better heat dissipation are the horizontal and vertical sections. Insulation bricks fume collection passages may be formed in several ways:
- Plaster, with application to the surface of the brick structure, reinforced with fiberglass. In the recipe may include materials such as sand, clay, lime, fireclay (refractory), perlite or vermiculite sand (with a volumetric weight of 75... 120 kg / m3).
- Skin insulation material. As masonry insulation typically use a mineral or basalt wool, manufactured in the form of mats. For the installation of wool used wooden or metal frames. Cells between horizontal and vertical elements forms a lattice fill insulation is slit to size and fixed with tape or glue. Then over sheathe flat asbestos cement slabs, plasterboard fire resistance or veneer tiles - clinker, granite, and others.
- Additional rows of bricks lining the outer side, which increase the chimney section. For this purpose, as a conventional clay brick (red) and a special fireproof - fireclay having yellow sand color and a pronounced grain structure.
Chimneys of asbestos pipes. Usually they are used for the removal of smoke and combustion products from cooking ovens, gas hot water columns automatic boilers, serving to heat coolant used in central heating systems, private houses, working gas, coal or wood. Their insulation is most easily done with the help of metal casings, which are made of galvanized roofing tin.
In the first phase structure is wrapped mineral wool segment forming a kind of bag and secured with tape or a soft steel wire knitting.
Further, the casing is made. The shield may be as round or square shape and composed of two halves interconnected by means of clamps. One of the conditions - that is, the distance between the inner surface of the casing and the outer side corresponds to the estimated asbestos pipe insulation thickness.
For the convenience of the installation of individual heat protection casing length portions should not exceed 50 cm. Each of them is at the bottom provided with a broadening to allow the installation overlying wear member to the one which is located below. When this overlap, which protects against ingress of water and snow casing, should be at least 5... 10 cm.
Sometimes the protection of asbestos-cement chimney using foil or mineral basalt insulation. After wrapping around and fixing, on top of it establish a fine mesh glass fiber or steel wire, which serves deposited on the armature to its strong heat-resistant layer of plaster, protected channel from mechanical damage and accidental shock loads.
Metal fume collection channels are made of metal tubing of the desired diameter. Mainly they are used for temporary heating devices, and other types of cooking stoves that are being built in the inner rooms of the house. How to insulate a metal chimney pipe? Thermal protection designs of this type is carried out on a "pipe in pipe".
Since the wall thickness of the metal tube is less than 1... 2 mm, we can always choose another thin-walled tube with a diameter greater than the chimney a double thickness of insulation. After installing and centering sinus therebetween filled with a mineral wool or any non-combustible granular substance - expanded clay or perlite, crushed foam or gas concretes. Individual section height not exceeding 50 centimeters, can be assembled on the ground and then mounted in a vertical position in the right place by the insertion of one element into another. When it is necessary to ensure that no gaps between the insulation able to form cold bridges which impair performance.
Warming Chimney refers to these types of construction works, most of which can be made with your own hands. To do this, you need to stock the necessary materials and components flues protection, as well as simple to prepare instruments that are always in stock at the home worker to independently engage in the construction and furnishing his house. It is better, if at the time when the insulated chimney, close the assistant will be present, is needed not only to perform ancillary works, but also for insurance at high-altitude works.
When installing thermal insulation on top, special attention should be paid to the reliability and stability of the use of ladders, scaffolding or ladders. You also need to use a construction helmet to protect the head, as well as special mounting belt or harness and secure mounting to prevent an accidental fall from the roof.