Table of Contents
The flue arranged with observance of all regulatory requirements is not only security guarantee of its operation, but also guarantee of efficiency of use of energy resources on heat supply. Within this article the principles of mounting are in detail stated and some calculations necessary for design and arrangement of chimney system of owner-occupied dwelling are given.
For what the flue is necessary?
The construction of flue is necessary for removal from the furnace, fireplace or other unit of heat supply of the house of combustion products. Smoke and gases are removed in the atmosphere through flue under the influence of the draft created in flue. The draft carries out also intake of the air containing oxygen in the furnace camera, thereby supporting fuel burning process.
Basic rules of the device of flue
The correct arrangement and mounting of flue depends on the correct design that, promotes decrease in fuel usage, heatlosses, guarantees compliance of air quality indoors to requirements of sanitary standards and ensures fire safety of building constructions. Selection of material for flue is not so big and various that simplifies task. Stainless acid resisting steel which part molybdenum is is considered the most modern material, but the frost-resistant clay brick remains traditional, usual material for wood-fired and universal furnaces and fireplaces.
Horizontal sites of the canal should not exceed 1 meter, at design and mounting it is necessary to meet strictly this condition as exceeding of length will surely provoke the increased sedimentation of soot on walls of flue and, as a result, weakening of draft, so and decrease in overall performance of all system.
The flue of their brick is constructed in strict accordance with calculations and with corrections to them, at the same time it is necessary to try to make pressurized construction which internal cavity have to be the most smooth. At installation of the new gas boiler the existing brick flue can be used only after carrying out its modernization consisting in installation in it steel acidproof pipe with providing gap.
Reducing adapters can be necessary in need of connection (insert) of pipe of the heating unit with flue at discrepancy of their diameters. Joints at the same time are required to be pressurized carefully. To exclude running off of condensate and pitches on outside pipe wall indoors, pipes it has to be docked in such a way that their expansions will be directed up. It concerns round metal pipes. To exclude formation of condensate and to provide fast warming up of pipe it is possible at the expense of external heat insulation.
In overlapping mounting of pipe is made with observance of measures of fire safety, building constructions have to be from flue at distance not less than 30 cm, the design of pipe in the place of passing through overlapping has to be provided with additional thickness of course. The metal pipe should not have joints in places of passing through overlappings and roof not less than 15 cm up and down. External part of flue (pipe) has to be strongly recorded and protected from wind. The pipe can be protected from atmospheric precipitation the deflector. If the flue is intended for withdrawal of products of burning from the gas equipment, the protective cap is forbidden to be established.
Flue wall thickness indoors has to be not less than 10 centimeters. Cross-section of flue has to be identical on all its extent. Calculate section proceeding from ratio 1 to 1.5 where flue section undertakes unit, and for 1.5 – fire chamber section.
The flue can be the general for several units allocating burning products under conditions:
- bend of smoke pipes no more than 30 degrees, deviation them down should not exceed 1 meter;
- all sites have to be the most smooth and not have roughnesses;
- the area of horizontal sites should not be less vertical;
- all units have to use the same type of fuel;
- the general flue has to be expected the greatest possible summed-up flow of products of burning from all devices.
The main constructive parts, flue beginning from below (from the furnace), are:
- The mounted pipe — is established on top of design of the brick furnace. As a rule, in it valves are mounted. At construction of mounted pipe the principle of block bond is surely observed: if in 1 row bricks keep within on two nearby, and with joint step, then in the 2nd row they stack perpendicular to the previous row, etc.
- The neck of cutting is place of passing of flue through overlapping, this part begins for 5 or 6 rows from mounted pipe to the overlapping plane.
- The first cutting is constructed with broadening of external part of flue, inside the section of flue should not change. Several rows of cutting ushiryat outside part of flue on 25 – 40 centimeters.
- The strut – the vertical part of flue located on the attic comes to an end strut at roof.
- The second cutting – the place of contact of flue with roof with broadening of external part of flue not less than on 10 cm. The otter does not allow hit of rainfall on the attic.
- The flue neck – is constructed also as well as strut, but after otter, outside of roof.
- Headband — is the completing constructive part of flue, it is carried out with broadening of flue outside. On headband establish metal cap or vane which purpose is protection of flue against hit of rainfall in it. Competently picked up cap increase in draft is promoted in flue, so and by furnace capacity in general.
Arrangement of pipe on the rooftop
When mounting pipe on roof of the building the requirement for ratio of heights of roof and pipe is strict:
- during removal of pipe from the fad to 1.5 meters, the pipe has to be above the fad not less than 0.5 meters;
- during removal from 1.5 to 3 meters, the pipe has to be level with the fad or above it;
- during removal more than on 3 meters, the upper point of pipe cannot be located below the line drawn from the fad to the horizon at an angle of 10 degrees.
Height of chimney pipe over roof, anyway, should not be less half a meter.
Once again about the main thing
Any owner having skills of economic construction jobs can build brick flue if he likes to work hands and at it it successfully turns out. Perhaps, the following advice will help you in difficult, but useful and pleasant business on construction of brick flue:
- Experienced stove-setters with ease break away bricks in the right place, receiving pieces of the size necessary to them. If you have no similar experience, use the grinding cutting machine.
- Bandaging of bricks is the key to qualitative laying, do not neglect it.
- The brickwork seams are thinner, the flue design therefore you do not hurry to cut off bricks is stronger. Have near at hand marker that the line of the machine cut has been accurately designated on brick.
- The most difficult elements of design are cutting therefore it is necessary to think whether you will manage to execute them. It is possible to make simpler if you are afraid that you will not be able to execute laying of cutting. Spreading flue, do it of same width. But in places of cutting provide concrete pads. For this purpose metal rods (armature) with a diameter of 5 – 7 mm, concrete of the high brand will be necessary for you. Where the design of flue has provided broadenings, build in pieces of armature of the necessary length laying, armature has to be in the laying, but not cross flue cavity. Afterwards by means of armature build wood form of the necessary height and width and fill in with concrete mix.
Care of flue
During the summer period it is necessary to check extent of pollution of flue. At detection on soot layer pipe walls more than 2 mm, flue need to be cleaned. If not to make it in time, then you risk to be left during the winter period without heating in the house, the thick layer of soot is capable to light up, and from high temperature and the high-pressure flue can simply break off. The furnace also is in danger at the increased soot content in flue.
For cleaning of flue it is possible to employ specialists, but it is possible also most to perform such work. For this purpose the rigid metal or plastic brush of large diameter, scraper on the long handle and rope will be required. After flue clearing you, most likely, should do clear-out of the room where you have located fire chamber or it is even necessary to paint ceiling and walls. Therefore it is better to combine cleaning of flue and repair indoors.
First of all, it is necessary to close hermetically fire chamber, ashpit and other openings from where soot falling is possible, to open valves. From the room where there is furnace, it is desirable to remove furniture or to carefully cover it with polyethylene film. It is recommended to close windows and doors that there was no excess draft.
Cleaning of flue is begun from above, at first by means of scraper get soot upward and put in the prepared tanks, then gradually go deep into flue cavity brush which will shake soot down. The fallen soot needs to be collected from fire chamber and ashpit and to throw out.
It is known that birch and aspen firewood emits soot most less, and here pine and other coniferous firewood promotes considerable formation of soot in flue. If to heat the furnace coal and briquettes, then the flue should be cleaned especially often.
There is checked national method of prevention of sedimentation of soot in flue: burning of potato cleanings in fire chamber, cleanings it is not obligatory to dry well, they are enough to be taken on newspaper 1 – 2 hours, and then to burn together with firewood. If you do not begin to throw out potato cleanings, and will burn down them regularly in fire chamber, then you should clean the flue less often.
The typical mistakes made at construction of flues
If at the device of flue serious miscalculations and negligence when mounting are allowed, then and it will be bad to function it. It is difficult to redo such work, it is unprofitable.
Unfortunately, there are typical mistakes made at nonprofessional execution of works:
- Incorrectly made calculations of the allowed loadings lead to destruction of the basis of flue. Before beginning to build flue it is necessary to know possibilities of the basis precisely. Certainly, all calculations have to be carried out on furnace projecting phase.
- Incorrectly chosen section and extent of flue reduce system efficiency.
- It is impossible to apply the materials for construction of flue which are not intended for this purpose. For gas boilers it is necessary to use acid resisting steel pipe. It is strictly forbidden to use plastic, asbestos-cement pipes.
- Badly executed heat insulation threatens ignition of designs and can lead to the tragedy.
At construction of flue there are no trifles, not without reason at all times good stove-setters were held in high esteem, behind them came from far away and asked to lay out the furnace and flue.