What Should Be The Optimal Height Of The Chimney Above The Roof Of The House

2023 Author: Philip Bishop | [email protected]. Last modified: 2023-05-24 22:24

• How to choose a chimney design
• Correct chimney device
• Determine the height of the pipe
• Graphical height adjustment method
• Ventilation device in a residential building
• Chimney designs
• Design and maintenance recommendations

Before you start building a house, you need to choose a project or order an individual development. To build even a small summer cottage, you need to know how to do it. You need to approach the chimney device responsibly, it is important to first determine the correct height of the pipe above the roof. It is relevant to get acquainted with SNiP41-01-2003 "Heating, ventilation, air conditioning", this document regulates the design standards for these sections of the project.

How to choose a chimney design

In order for the smoke from the combustion products to go outside, you need to create a draft. It occurs due to the temperature difference between the hot air in the oven and the outside. The heated air, getting up, begins to cool down, due to the pressure drop in the pipe, its movement begins, this is the thrust.

In order for the heating systems to function normally, and to obtain high efficiency, it is necessary to calculate the height of the chimney above the roof and its cross section. A large clearance in the pipe will create strong draft, rapid air cooling and condensation formation. This is undesirable for the heating system.

If by increasing the height of the pipe and, accordingly, making its cross-section smaller, this will increase the draft, a lot of cold air will flow, which will lead to unnecessary heat loss. The stove or boiler will have to be heated for a long time and use a lot of fuel for heating.

Correct chimney device

One of the main parameters for the calculation is the height of the pipe above the roof ridge. Correct calculation will help create strong draft in the heating system and save fuel. When making calculations, you need to take into account the instructions in the instructions for the heating unit and the recommendations of the following documents - SNiP41-01-2003 and SP 7.13130-2009.

You should know the rule that the chimney along the entire length from the firebox to the place where the smoke is released into the atmosphere cannot be less than 5 m long. With a flat roof, the smallest chimney height above the roof is set at 1.2 meters.

If the roof is multi-level, with complex differences in height, the calculation becomes more complicated. It is better to leave such calculations to specialists.

The cross section of the chimneys depends on the power of the boiler and should be as follows, mm:

• 140 × 140 - with a heating power of less than 3.5 kW;
• 140 × 200 - at a power of 3.5 - 5.2 kW;
• 140 × 270 - with its value of 5.2 - 7 kW.

For round chimneys, the cross-sectional area must correspond to the dimensions of the rectangular ducts.

Determine the height of the pipe

Consider what SNiP indicates to determine the height of the chimney above the roof. It is equal to:

• For a flat roofless roof, the height of the chimney above its covering cannot be less than 50 cm;
• on the same roof, only with the device of high parapets, the upper mark of the pipe must exceed the mark of the fence by 50 cm;
• when the chimney is located on the roof in a place located closer than 1.5 meters horizontally from the center of the ridge, the height of the chimney above the ridge of the roof will require 50 cm or more;
• the location of the chimney at 1.5 - 3.0 meters from the center of the roof horizontally will require a pipe height equal to or slightly higher than the ridge;
• if the chimney comes out to the roof close to its edge and is further than 3.0 meters from the ridge point, its height is determined by a line drawn from the ridge point to the chimney at an angle of 10 ⁰ downward from the horizon.
• when located next to a building under construction, other tall buildings, the chimney should protrude above its highest point. If there are structures with a higher upper elevation nearby, plantings, use the calculation along a line of 45 ⁰ to the horizontal, built from the highest point to the pipe. Its top cannot be located below this line.

Graphical height adjustment method

With a simple roof structure, you can try to graphically determine which pipe height above the roof would be most appropriate.

First you need to arm yourself with pencils, paper, a ruler. Draw the projection of the pitched roof on a scale. We mark the point of location of the skate. Next, we draw the axis of the location of the chimney, with a horizontal line we indicate the position of the ridge point of the roof.

We measure the distance between them. If it is less than 3 m, draw the chimney 50 cm above the ridge point (using the scale of your drawing), measuring the entire height from the roof surface to the top line of the pipe, we get the length of the chimney above the roof, applying the scale, and determine its real height.

If the pipe is located more than 3 meters from the ridge, the drawing will have to be complicated. From the horizontal, passing through the top of the ridge, lay down a line at an angle of 10 ⁰. Its place of intersection with the center line of the chimney will mean its upper cut. Next, you will have to measure this distance and convert it to a real value using the selected scale.

Ventilation device in a residential building

When installing a heating boiler for heating a residential building, ventilation of the room where it is located must be provided. It will help to determine the height of the ventilation pipe above the roof SNiP41-01-2003 "Heating, ventilation and air conditioning". The calculation of its height is carried out in the same way as determining the height of the chimney. Its location relative to the ridge, the roof structure, the location of high-rise buildings and other structures are taken into account.

What should be the height of the chimney above the roof if there is a chimney nearby? The ventilation hood must be below the chimney to prevent smoke from entering the room. The distance between the ventilation and smoke shafts must not be less than 5 m.

Chimney designs

For the heating system to work efficiently, you need to choose the right design for the flue ducts. The most used are:

• brick, the most durable, heat-absorbing. The disadvantage is the difficulty in manufacturing;
• asbestos-cement, inexpensive, light in weight and in installation, but loses heat;
• steel single-circuit, inexpensive, light weight, but not heat-resistant and short-lived;
• steel in two circuits, made of two pipes with intermediate insulation, a good modern option;
• ceramic, consists of refractory ceramics, insulation and a protective layer of concrete. Not a bad option, but tough.

Design and maintenance recommendations

When building a chimney, consider the following:

• when laying a brick chimney, the seams must be sealed, the inner surface should be made even and smooth;
• to reduce the load of the brick structure on the base in the attic, it is necessary to make a transition to lighter pipes;
• when choosing the cross-section of the chimney and the size of its internal passage, the characteristics of the heating equipment, its power should be taken into account;
• metal and asbestos pipelines are installed vertically;
• in order for the chimney to work efficiently, it must be constantly cleaned of soot;
• to prevent insects, birds or precipitation from entering the system, it is allowed to install protective caps on the pipe;
• when using chimneys above 1.2 m, they must be reinforced with additional elements.

Having realized how important it is to determine the height of the pipe above the ridge of the roof of the house, you can make the right choice of this parameter. This will ensure a comfortable and comfortable existence in the new home.