L_BC_1 L-Building Construction I

CHIMNEYS

Keywords: Chimney, vent connector, flue (venthole), chimney casing, effective height, sweep opening, pickup opening

BASIC CHARACTERISTICS AND CLASSIFICATION OF CHIMNEYS

Chimneys are designed to remove flue gases from appliances to a free space outside the building where they are scattered so as not to endanger the quality of the living environment of the house's residents.

Chimneys are among the most stressed building elements - they are exposed to extreme temperature conditions and aggressive flue gases.

The chimney consists of:

  • One or more chimney flues
  • Chimney casing
  • Sweep openings
  • Pickup openings
  • Vent connector
  • Chimney heads, or extensions

Classification of chimneys

According to the appliances we distinguish chimneys for:
  • Solid fuel chimney
  • Liquid fuel chambers
  • Gaseous fuel chimney
According to the structure, we distinguish chimneys for:
  • Single-layer chimneys - The chimney's passage is formed by a chimney casing
  • Multi-layer chimneys - The chimney consist of a structure consisting of a chimney liner, an insulating layer and a chimney casing
According to the location of chimneys, we distinguish chimneys for:
  • Fitted or built-in chimneys
  • Solitary chimneys
According to the ground plan shape of the chimneys we distinguish:
  • Square chimneys
  • Rectangular chimneys (up to 1: 1.5)
  • Circular chimneys
According to the size of the flue to distinguish:
  • Narrow chimneys (up to 40,000 mm2)
  • Medium chimneys (over 40,000 mm2)
  • Man chimney (minimum cross-section up to 10 m high is 450 x 450 mm)
According to the built-in material we distinguish chimneys for:
  • Chimneys made of non-flammable or non-easy possibly flammable materials
  • Chimneys made of materials with an absorption capacity not exceeding 20% of the specific weight
  • Chimneys made of materials resistant to the effects of flue gases
  • Chimneys made of frost-resistant materials
According to the arrangement of flues, we distinguish chimneys for:
  • Continuous chimneys
  • Storeys chimneys
  • Overflow chimneys
  • Tree chimneys
According to continuous longitudinal axes we distinguish chimneys for:
  • Direct chimneys
  • Moving chimneys

DESIGN AND IMPLEMENTATION OF CHIMNEYS

The flue gas is exhausted by chimney flues formed in the chimney casing. The hole through which the flue gas is fed into the flue is called the vent connector. Other openings in the chimney enclosure are used for cleaning the flues - pickup hole and sweep hole. The chimney ends the chimney head.

The chimney draft depends on the difference in mass of hot combustion gases and fresh air in the chimney head. The draft of the chimney also depends on the size and shape of the flue, on the smoothness of the interior surface of the flue, and also on the effective height. The effective height is part of the chimney from the chimney to the chimney head and is intended for flue gas removal. Part of the chimney from the flue connector to the chimney soil is used to collect solids of flue gas and condensate.

The chimney flue should have a constant cross-section along the height. Chimneys may contain flue for exhaust gas and may have ventilating vents (vents). Flues for exhaust gas cannot be used as ventilation vents and vice versa. Flues are designed generally vertical and straight. Any deviation from the vertical should not be greater than 15°. The flues may have a square, circular or rectangular cross section.

The chimney casing should be non-flammable, low absorptive and resistant to flue gases. The chimney passing through the interior or building structure shall not have an outer surface temperature above 52°C during operating. A part of the chimney directly exposed to atmospheric influences should be protected from freezing.

Single-layer chimneys must have a masonry chimney thickness of at least 140 mm. The curvature of chimney's flue shall be formed by a smooth curve with a radius of at least 300 mm. The outer surface of the monolayer masonry chimney can be plastered or sprinkled, or fitted with a non-flammable coating.

Multi-layer chimneys are usually three-component. They are consisting of chimney liner, an insulating layer and a chimney casing.

Openings in the chimney must always be accessible. The flue connector is part of the chimney, which connects the appliance and the chimney flue to which the exhaust gas. The flue connector cannot be larger than the light cross section of the flue into which they are inserted. The flue connector should be direct and toward the flue should rise. Sweep openings are designed for flue and liquid fuels that cannot be swept straight through the chimney head. The holes are placed over the roof or in the attic. Pickup openings are designed at the level of the soil of the chimney flue. The floor around the selection holes must be non-combustible. All chimney openings should be closed with chimney door made of non-combustible materials.

Chimneys are positioned above the roof so high that they do not disturb the environment or pollute the surroundings with flue gases. The smallest permitted chimney height is given by the type of roofing and the location of the chimney

POS1 Chapter 9 - 12
POS1 Chapter 1 - 12
12.-chimneys.pptm
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