Chimney Deflector, Including Its Types With Characteristics And Principle Of Operation, As Well As Installation Features

2024 Author: Bailey Albertson | [email protected]. Last modified: 2024-01-17 22:26

Chimney deflector: selection and construction of an effective draft amplifier

Good draft is the key to normal operation of the stove, therefore, the design of the chimney should be given no less attention than the heating device itself. To improve the aerodynamic properties of the chimney, a special reflector, or, in other words, a deflector, is installed on its edge. This simple device will not only increase traction, but also protect the smoke channel from debris and precipitation. There are various designs of reflectors ranging from devices designed by home craftsmen to models that have been worked on by the engineers of the research institute. Any of these deflectors can be made by hand if you follow the drawings and have minimal skills in working with metal.

Content

• 1 Why do you need a chimney deflector and how does it work

• 2 Device and types of deflectors

  • 2.1 Deflector TsAGI
  • 2.2 Poppet
  • 2.3 Round "Volper"
  • 2.4 Grigorovich deflector
  • 2.5 H-shaped
  • 2.6 Rotating
  • 2.7 Deflector-vane

• 3 How to make a deflector with your own hands

  • 3.1 What is needed to make a TsAGI deflector

  • 3.2 Design work

    3.2.1 Table: design dimensions of TsAGI deflectors for chimneys of various diameters

  • 3.3 Making templates

  • 3.4 Installation instructions

    3.4.1 Video: do-it-yourself TsAGI deflector on the chimney

  • 3.5 Features of manufacturing rotating reflectors

    3.5.1 Video: do-it-yourself vane deflector

• 4 Installing a deflector on the chimney

Why do you need a chimney deflector and how does it work

Even the best stove will not be able to show good results if its chimney does not create the necessary draft. It is this factor that affects the efficiency of air supply and the timely removal of exhaust gases.

Strong wind and sudden changes in atmospheric pressure contribute to the deterioration of traction and a decrease in efficiency. These weather factors cause turbulence in the exhaust gas flows and can cause reverse thrust, in which the direction of movement of the combustion products is reversed. In addition, precipitation and debris easily enter the open chimney, which significantly reduces the cross-section of the smoke channel. It is clear that there can be no question of any normal operation of the furnace in such conditions.

As a deflector of air currents, the deflector, in fact, serves as a normal wind barrier.

Bumping into an obstacle, the air flow bypasses it from both sides, so a low pressure area appears immediately behind the reflector. This phenomenon has been known since the school physics course as the Bernoulli effect. It also contributes to the enhanced removal of gases from the combustion zone and allows the furnace to be supplied with the required amount of air.

The principle of operation of the deflector is based on the appearance of a low pressure zone on the leeward side

More recently, engineers have been closely involved with this topic. During numerous experiments, they found that just by choosing the right deflector, the thermal efficiency of the furnace can be increased by 20%. It is also important that the reflective device improves the aerodynamic properties of the chimney regardless of the strength and direction of the wind, the presence of precipitation and other weather factors.

Device and types of deflectors

Despite the existence of many models of deflectors, they are basically built using the following structural elements:

• inlet pipe with nipple or flange connection;
• an outer cylinder called a diffuser;
• housing;
• a cone-shaped cap called an umbrella;
• brackets for attaching an umbrella.

Different deflectors have common structural elements

For making deflectors with your own hands, galvanized or stainless steel sheet is best suited. In addition to these materials, the industry has mastered the production of devices with a protective enamel layer or a heat-resistant plastic coating.

Among the many deflectors that you can do yourself, there are several of the most popular designs.

Deflector TsAGI

The TsAGI deflector is a universal device that can be installed on any pipe - stove, exhaust or ventilation. Developed at the Central Aerohydrodynamic Institute. Zhukovsky device has a simple design with an open flow path and reverse draft protection. There are two types of TsAGI reflectors designed for external or internal installation. Due to its many advantages, this type of deflector has gained wide popularity among DIYers. However, the design is not without its drawbacks. The “weak link” is the narrow flow area that can be overlapped by a layer of ice on the inner cylinder. In addition, the TsAGI deflector is not efficient enough in light wind and calm - in these conditions, its design creates little resistance to natural draft.

TsAGI Delector features a simple design and excellent performance

Poppet

This deflector got its name because of several cones (plates) in its composition and refers to devices with an open flow path. The reflector has a protective umbrella combined with a cone and a lower part in the form of a hood with a hole for smoke outlet. Vacuum occurs due to the plates directed towards each other, which form a narrowing channel for the incoming air flows.

In a disc-shaped deflector, a vacuum occurs in the gap between the cones directed towards each other

Round "Volper"

The device has a design similar to the TsAGI reflector. The differences concern only the upper part of the deflector. A hood that protects the inside of the chimney from debris and precipitation is installed over the diffuser, which eliminates some of the shortcomings of the device developed at TsAGI. Zhukovsky.

"Volper" has minimal differences from the TsAGI traction amplifier, which provide it with advantages in the absence of wind

Deflector Grigorovich

One of the more repeatable designs is the TsAGI Advanced Deflector. The smoke that comes from the chimney passes through the tapering channel of the diffuser, which increases the speed of its outflow. The Grigorovich deflector is best suited for chimneys installed in lowlands and in areas with weak air movement, since it is able to provide good draft even in complete calm.

Grigorovich deflector - ideal solution for areas with weak air currents

H-shaped

Deflectors, the silhouette of which resembles the letter "H", are designed to equip chimneys of powerful stoves and boiler installations. In such devices, the exhaust gas stream is split into two parts and exits with acceleration through two side diffusers. The advantages of the design consist in a significant improvement in traction when air masses move in any direction. In addition, the H-shaped deflector does not require the installation of a visor, since the chimney mouth is protected by the transverse pipe of the device.

H-shaped traction amplifiers are designed for installation on chimneys of powerful heating units

Rotating

The device is made in the form of a sphere with many curved side blades. The presence of blades allows the device to rotate in a certain direction and work like a turbine. Rotary deflectors are best suited for gas boilers and do an excellent job of protecting the chimney from debris and precipitation. The disadvantages of devices of this type are their low efficiency in case of icing and no wind.

Multiple blades of the rotating deflector create thrust like a turbine

Deflector-vane

Such a reflector has a rotating part (vane) that turns when the wind direction changes. In this case, the curtain of the deflector obscures the chimney from the incoming air masses and contributes to the appearance of rarefaction from the leeward side. Thanks to this, an active suction of combustion products is carried out, which excludes back draft and the formation of sparks.

The deflector with a vane can be rotated, orienting the reflector exactly across the direction of the wind

How to make a deflector with your own hands

Regardless of which model of the deflector is chosen for do-it-yourself manufacturing, the work is carried out in a certain sequence. First, measurements of the chimney are made and, based on tables and drawings, the parameters of the selected structure are calculated. Further, a sweep of the deflector body and drawings of parts with real dimensions are made. After that, the patterns of all the constituent parts of the deflector are cut out of the cardboard and transferred to the metal. All that remains is to cut out the blanks of the parts and assemble them into a single structure.

As an example, we will show how you can build one of the most popular structures in our country - the TsAGI deflector. Such a chimney reflector can be made by hand, even with minimal plumbing skills.

What is needed for the manufacture of a TsAGI deflector

Before starting work, you should prepare the following materials and tools:

• sheet galvanized or stainless steel up to 1 mm thick;
• thick cardboard for making patterns;
• pencil;
• ruler;
• compass;
• a scribe made of tool steel;
• pliers;
• scissors - office and metal;
• drill and drills for working with steel;
• riveter.

To build rotating deflectors, you will additionally need bearings, metal pipes and rods, bolts, nuts and a threading tool.

Design work

Before proceeding with cutting the metal, it is necessary to calculate the design parameters and make drawings. To determine the dimensions of the deflector, it is required to measure the inner diameter of the chimney pipe (d) and calculate according to the following ratios:

• outer ring width - 2d;
• the height of the outer part with the cap - 1.2d + d / 2;
• diameter of the diffuser in the upper part - 1.25d;
• the diameter of the visor (umbrella) varies from 1.7d to 1.9d;
• mounting height of the outer ring - d / 2.

The proportions of the sides are applied to the drawing of the TsAGI deflector, which are necessary to determine the dimensions of individual elements

For the convenience of calculations, the external parameters of the deflectors are included in the table, where they are presented for the most common chimney sizes.

Table: design dimensions of TsAGI deflectors for chimneys of various diameters

Chimney diameter, mm	Outer ring diameter, mm	Height of the outer ring with a cap, mm	Diffuser diameter on the outlet side, mm	Cap diameter, mm	Outer ring mounting height, mm
100	200	120	125	170-190	50
125	250	150	157	212-238	63
160	320	192	200	272-304	80
200	400	240	250	340-380	100
250	500	300	313	425-475	125
315	630	378	394	536-599	158

Measurements and calculations should be carried out very scrupulously, because the aerodynamic qualities of the structure and the possibility of its installation on the chimney without cracks and gaps depend on them. When designing a deflector, not only the diameter of the chimney is taken into account, but also the shape of its section. For a square chimney, a deflector of the same configuration will be needed, although the presence of corners affects the efficiency of the traction amplifier.

Making templates

The pattern of the diffuser of the TsAGI deflector is a sweep of a truncated cone.

The pattern for the manufacture of the diffuser of the TsAGI deflector is a truncated cone

To make a pattern for a part, you need a calculation using the following data:

• chimney diameter - d1;
• diameter of the diffuser on the outlet side - d2;
• maximum diffuser height - H.

An umbrella pattern is even easier to make. For this, a circle with a diameter of 1.7d is drawn on cardboard. After that, you should select a sector with an angle of 30 degrees at its base and leave an overlap of 15–20 mm to fix the side of the cone.

To fix the side of the cone, it is necessary to leave a lap

It remains to cut the piece along the contour and separate the triangular area (selected sector) from it.

Installation instructions

After the patterns of all parts of the TsAGI deflector are cut out, a full-scale model is made and its compliance with the calculated dimensions is checked. In the future, this will help to avoid situations when individual parts of the device do not fit together, and the connecting dimensions of the structure do not correspond to the diameter of the chimney.

Full-scale modeling of cardboard deflectors avoids operational errors

After checking, the model is disassembled into its constituent elements and proceeds to the manufacture of metal blanks. This work is done in stages.

1. The contours of the patterns are transferred to a metal sheet, for which they use a scribe made of hard alloys, chalk or a simple pencil. At the joints, add 20 mm each in order to leave a slight overlap.
2. With the help of metal scissors, a sheet of galvanized or stainless steel is cut.
3. Sections of the outer contours of the parts are bent no more than 5 mm, tucked in with pliers and tapped with a hammer.

4. The blanks of the outer ring and the inlet pipe are rolled up in a ring with a 20 mm overhang of one part to the other, and through holes are made along the centerline of the resulting overlap. The drilling step depends on the size of the elements and varies from 20 to 60 mm.

   

   After folding the diffuser into a ring, its edges are fixed with rivets

5. The parts are connected with rivets or bolts.

6. The cap, diffuser and protective visor are made in the same way. Metal is tapped along the bending lines with a hammer. This will make the sheet thinner and allow you to do much less effort when processing it.

   

   The overlap, which will allow fixing the deflector cone, must be taken into account even at the modeling stage.

7. 3-4 brackets are made, by means of which the individual parts of the deflector will be connected to each other. For this, strips 30 mm wide and up to 20 mm long are cut from a metal sheet. To increase the rigidity of the holders, a 5 mm wide flange is made along their outer edge, which is tapped with a hammer.

8. An indent of 50 mm is made from the inside of the cone and holes are made for attaching the brackets.

   

   After attaching the brackets to the cone, it is necessary to bend them in the direction opposite to its top

9. The metal strips are attached to the umbrella and bent at a 90 degree angle.

10. The cone with brackets and a protective cap are attached to the diffuser.

    

    For the final assembly of the deflector, riveted joints are used.

11. The structure is inserted into the outer ring and fastened with riveted joints. At this, the assembly of the TsAGI deflector can be considered complete.

    

    If you follow the instructions exactly, you get a functional deflector

In the same way, you can make any type of deflector with your own hands. The only exceptions are rotating structures, which, in addition to metalwork, require the manufacture of a rotary assembly.

Video: do-it-yourself TsAGI deflector on the chimney

Features of the manufacture of rotating reflectors

Since the manufacture of rotating deflectors has a number of features, let us consider in more detail how to build a traction amplifier with a rotating vane.

To manufacture a deflector with a rotating vane, you will need project documentation

In addition to the tools and materials that will be needed to make a structure from TsAGI, you should add:

• long threaded rod M10-M12;
• a piece of steel pipe Ø 30–50 mm;
• 2 bearings with an outer and inner diameter that matches the selected pipe and stud;
• M8 bolts for fastening rotation units;
• nuts М10-М12 in the amount of 8 pieces;
• set of taps;
• wrenches.

A deflector with a weather vane can be given the appearance of an outlandish bird - it all depends on the imagination and skills of the master

The initial stages of work do not differ from the manufacture of static deflectors. First, they draw up a drawing, cut out the patterns and transfer their contours to sheet steel. The workpieces are cut with metal scissors or a jigsaw. The wind vane shutter is assembled with rivets. The only difference is that you will need to attach brackets to the body, by means of which the reflector will be fixed on the axis.

Further, the work proceeds according to a different scenario:

1. The stud is shortened so that its length is sufficient to fix the bearings and the reflector housing.
2. Bearings are installed on the axle. The distance between them should ensure the stability and solidity of the swivel unit. The rolling units are fastened with a pair of nuts tightened with sufficient force.
3. Cut off the desired piece of steel pipe. In the places where the bearings will be placed, drill and cut M8 threads.
4. Holes are drilled in the pipe to which the holding brackets will be attached.
5. A ring (sleeve) corresponding to the outer diameter of the chimney is bent from a piece of steel strip 1.5-2 mm thick and 150-200 mm wide.
6. Four brackets are cut from the same strip, with which the ring will be attached to the pipe of the rotary device.
7. The reflector is attached to the axle using two pairs of nuts, which fix the vane in the upper and lower parts.
8. The axle with bearings is inserted into the pipe and fixed with M8 bolts.
9. A fastening ring is installed on the deflector. For this, the manufactured brackets are alternately fixed on the pipe of the swivel unit and the connecting sleeve. This completes the assembly work.

During operation, it is necessary to monitor the state of the lubricant in the bearings, otherwise the structure will rotate with difficulty or even jam.

Video: do-it-yourself vane deflector

Installing a deflector on the chimney

When installing the deflector, a number of conditions must be met that affect the efficiency of its operation:

• in areas with gusty winds, it is rational to use H-shaped traction amplifiers;
• in the northern regions, it is undesirable to install rotating deflectors;
• when installing a round deflector on a square chimney, a special adapter is made;
• the traction amplifier is not recommended to be installed where neighboring buildings can create an aerodynamic shadow;
• the device for enhancing traction must be blown by the wind from any direction.

There are two ways to install the deflector. In the first case, the traction enhancement device is attached directly to the chimney using clamps, rivets or threaded connections. The second method involves attaching the deflector to a special adapter, the inner diameter of which allows you to simply fit the device onto the chimney. The latter method is convenient to use if access to the chimney is limited or it is of considerable length.

To fix the deflector on the chimney, a metal clamp of a suitable diameter is suitable

In general, the installation of the deflector looks like this:

1. A piece of pipe is selected, the diameter of which is several millimeters larger than the size of the chimney.
2. At a distance of 10-15 cm from the end of the workpiece, holes are made for fasteners. The same drills are made in the reflector connecting pipe.
3. The holes in the pipe and the deflector are aligned, pins are threaded through them and fixed with nuts on both sides. In the future, the pins protruding into the branch pipe will serve as a stop for the chimney pipe.
4. The device is lifted up and placed on the chimney. For the final fastening of the structure, a metal clamp of a suitable size is used.

In order to eliminate the danger of air leakage, the joint is sealed with basalt wool, asbestos cord or any heat-resistant sealant.

Not only the efficiency and performance of the heating unit, but also the safety of your loved ones, depends on how competently the draft in the chimney will be organized. Even a simple self-made deflector can improve the removal of exhaust gases. It is only necessary to adhere to the exact dimensions and in the manufacture of the device for improving traction, show the utmost care and increased attention.