A house with a fireplace, stove or boiler is necessarily endowed with a chimney that goes out through the roof into the outside environment. If you look at the roofs of private buildings, you can see how various metal structures are located above the pipes. These are the caps. In this article we will tell you what they are for, what they are and how to mount them yourself.
Features and purpose
The hood, installed on the chimney head, resembles an umbrella or visor. It can look simple and practical, or spectacular and unusual. Observing the roofs of houses, it can be noted that not all pipes have a protective umbrella.
This is because this chimney element contains its pros and cons.
Advantages and disadvantages
The product may seem like a decorative end of a brick pipe, but in fact the cap performs quite practical functions
- The structure above the chimney protects against rain and snow.
- It prevents leaves, small branches and other debris from getting into the chimney.
- If the cap is stretched over the pipe, the birds have no chance to make a nest in it.
- Over time, the negative impact of the external environment destroys the brickwork of the head. The task of the hood is to extend the performance properties of the pipe coming out to the roof.
- During strong gusts of wind, reverse thrust can form, which is successfully prevented by the protective visor, redistributing the air flow.
- Decorative items become a real decoration of the roof. Sometimes a beautiful weather vane is added to them. With its help, you can always find out the direction of the wind.
Despite the importance of keeping a protective cap over the chimney head, not everyone thinks it is necessary. Several negative factors force some owners of private houses not to use this design. There are few cons, but they are significant.
- The hood, installed in the path of the outgoing smoke and combustion products, delays them to some extent. This is especially evident in the case when an unsuccessfully chosen design narrows the channel.
- During the combustion of fuel, water vapor is generated. It rises with the smoke and condenses on the inner surface of the sun visor. In winter, this leads to the formation of icicles that can block the chimney channel. Some modern flue gas passages are equipped with a special compartment that collects moisture, and this allows leveling the problem of condensation.
- Caps made of thin material burn out within five years and need to be replaced.
Based on the above arguments, some owners consider the cost of a product to be unjustified, from which there may be not only benefits, but also problems.
Now let's figure out how the chimney cap works. It consists of a number of elements.
- Weather vane cap (protective umbrella). This is the part that we see stretched out over the pipe. It has different shapes and designs, but all of them must protect the chimney from negative manifestations of the external environment.
- Dropper apron. This element protects the pipe head from dampness caused by drops bouncing off the cap during rain.
- Brackets. They hold the umbrella over the apron, creating sufficient ventilation space between them. The number of brackets is determined by the dimensions of the visor, and the distance between them is from 30 to 50 cm.
- Anchor bolts.
In addition to the protective function, the cap also performs other important work. The principle of operation of the system is as follows: the air flow is redirected by the cylindrical walls of the hood in a circle and pushed upward. At this moment, smoke is sucked in and pulled out of the chimney, which allows more intense air movement in the chimney itself. The area of reduced pressure formed under the bell makes it possible for smoke from the combustion chamber to rush towards it.
Those who decide that a pipe cap is necessary should familiarize themselves with the regulatory documents and SP 7.13130.2013. It is noted in them that the shape of the visor should not affect the calculated norms of thrust, worsen the process of removing air streams. More complicated structures on the chimney are foreseen at the stage of the roof design.
Modern builders have a large selection of chimney caps. These products are produced in different forms: they are decorative, with weather vane, stationary or folding, with spark arresters. TO
Glasses can be classified by design and shape.
Such systems have different design features. The most common are the following types.
- With opening lid. Convenient design for easy maintenance of the chimney.
- With a spark arrester. The product contains walls made of metal mesh and covered with a cap. The protection is installed on the chimneys of the baths, where sparks are successfully extinguished against the mesh walls of the spark arrester.
- With deflector. A chimney with a deflector in the best way regulates and enhances draft. This device increases the efficiency of a furnace or boiler by 20%.
- Often, pipes are decorated with forged or carved structures., supplemented by weather vane.
A wide variety of hood shapes allows you to choose an option that suits the architectural features of the house. Sometimes the shape of the chimney repeats the outline of the roof of the cottage and is gable, hip, flat, hip. You can also find caps of a round, hipped, vaulted, spire-like shape.
Sometimes protective structures look so impressive and unusual that they become a real decoration of the building. To be convinced of this, it is enough to familiarize yourself with a selection of photos of similar products.
With interest you can consider the plot scenes from the life of people or animals, presented in the form of figures on the surface of the visor
A cap crowned with a nest of storks with silhouettes of birds is considered a sign of happiness for the master's house. Their family's presence on the roof is as symbolic as the horseshoe at the front door
Sometimes the visor itself is transformed into a sculptural image of a bird, teapot or any other figure. It is much more pleasant to look at such a product than a regular cap
Such an extravagant design may appear for the owner, who takes the concept of "protective umbrella" literally
The complex model of the cap resembles a house with its own chimney, which is at the top of the chimney
The forged structures present in the exterior of the building are perfectly supported by the appearance of the canopy over the chimney duct
A weather vane theme is not uncommon for a protective cap. Swirling figures not only decorate the highest point of the house, but also allow you to know the direction of the wind
And this pipe is decorated with an amazingly beautiful copper product with four spiers on round turrets
In places where the chimney is led out to the roof surface, a gap may form between the pipe and the roofing material. The situation is resolved by a silicone cone, the dimensions and shape of which are selected individually for the pipe. Silicone can withstand temperatures up to +300 degrees and at the same time creates the necessary tightness.
Then a protective cap is installed over the chimney.The material from which it is made must withstand weather conditions of varying intensity and be resistant to fading. Finding the hood on the roof complicates its maintenance, so it is better to choose a model that is more expensive but more durable. The visors are made from the following materials.
- Copper. Copper alloys are most commonly used. Of all the materials, it is considered to be the most reliable. With a high-quality installation of the visor, the product can last up to 70 years.
- Stainless steel. It is also distinguished by its durability, lasts up to 50 years, and is cheaper than copper. Loyal price and durability provide the products with stable popularity.
- Titanium alloys. Soft yet strong and durable metal. The caps are of good quality.
- Cink Steel. Visors made of this alloy can last up to 20 years. But if a thin sheet of metal is used for the product, burnout occurs much faster.
When choosing a hood for a chimney, pay attention to the following points:
- pipe material;
- type of fuel for combustion;
- size and shape of the outlet.
All these factors are important to take into account, since the temperature of the combustion products exiting with the smoke will be determined by the type of fuel. Building material reacts differently to temperature readings.
Chimneys made of rectangular or square bricks can cause turbulence and impairment of draft.
The rough surfaces of the brickwork retain soot and soot on themselves, which over time leads to a narrowing of the channel. Traction in this case also deteriorates.
In such a situation, the best purchase would be a hood with a deflector. It will improve the draft properties of the chimney and increase the boiler efficiency. The deflector will not allow moisture to settle on the pipe walls, which will protect it from dust and soot sticking. Such a device will create a zone of reduced pressure under the visor, into which combustion products and smoke will actively rush.
Now let's figure out which cap is needed for ceramic pipes or sandwich-type structures (pipe in pipe). They are usually placed on solid fuel boilers. The products have a smooth surface and are often equipped with a compartment for collecting condensate, which to a greater extent prevents the deposition of soot on the walls of the pipes. The stability of the thrust is influenced by the height of the structure: it must be at least 8 meters. If it is necessary to lower the chimney, you can install a hood with a deflector. The pipe, reduced by 20%, will retain traction activity.
For a gas generator boiler, in which the escaping volatiles are burned separately, a canopy with an open nozzle should be installed. When fully protected from the external environment, it will not interfere with the removal of smoke at low temperatures. The same cap is suitable for a diesel boiler.
A conical umbrella with an open nozzle is necessary for boilers with a high level of efficiency, for which the traditional pyramid is contraindicated. The rounded cone top model is less prone to icing. When installing the structure on the chimney, you should work out the optimal distance to the head.
A too-raised visor will not keep the channel from debris and birds, and if it is lowered, you can get problems with traction.
In most cases, private house owners prefer to purchase ready-made hoods that meet the requirements of their chimneys. But lovers of doing everything with their own hands can make a visor on their own.
Tools and materials
Before starting work, you should purchase a galvanized iron sheet or other suitable material in advance, collect the necessary tools. To work, you need the following:
- metal sheet 0.6-0.8 mm thick;
- scissors for metal carving;
- rubber mallet;
- metal corners;
- welding machine;
The working process
First you need to make a sketch of the future cap.Knowing the parameters of the pipe head, it is necessary to calculate the dimensions of the product in such a way that the surface of the visor on all sides overlaps the top of the chimney by 10 cm. It is important to know the dimensions of both the outer and inner parts of the pipe, then the cap will fit perfectly. Next, the following actions are performed.
- A visor pattern is made from a sheet of cardboard.
- They put it on a sheet of metal and draw with a felt-tip pen.
- The surface is cut along the drawn lines using metal scissors.
- A box is formed in the form of a house, fixed with corners and rivets.
- Using a pattern, the drawing is transferred to the metal and a dropper is cut out. The apron is formed with the participation of a bending machine. Rivets are used for fixing.
- The brackets are cut into strips of metal several centimeters wide. The visor and the drip are connected into a single structure, maintaining a distance between the brackets of no more than 50 cm. This work is performed by welding.
- The finished structure is painted in a suitable color and fixed to the chimney.
Before attaching the hood to your own pipe, you should familiarize yourself with the regulations. In addition to decorative and protective properties, the product affects the process of removing combustion products into the external environment. For this, it is important to know the calculated draft rates.