Passage of a chimney through ceilings and roofs.
When a chimney goes through ceilings an expansion gap of about 2-3 cm from each side of the chimney should be kept. It should be filled with incombustible material. Mineral wool is recommended. In case a chimney goes through wooden ceilings or roof construction 5 cm gap should be kept.
Placement of a chimney towards walls.
When a chimney is placed by walls made of easily inflammable materials a gap of 5 cm between the chimney and wall should be kept. The gap has to have proper circulation (e.g.: due to entry holes at the floor level and escape ones below ceiling). Distance between a chimney and incombustible walls can be 5-10 mm. The gap ought to be filled with flexible composition. The junction should be supported with plaster net and covered with expansion battens,
Passage of horizontal sections of flue through walls.
The point where flue goes through walls made of easily inflammable materials incombustible protection should be used at a range of minimum 15 cm. (mineral wool, cellular concrete). If the flue goes through incombustible wall dilatation of mineral wool should be used on the whole length of the passage.
Placement of elements towards scoot holes.
Soot holes should be placed 40 cm away from elements and parts made of easily inflammable materials. Usage of thermal coverage for soot doors allows to shorten the distance to minimum 20 cm Easily inflammable floor in front of soot doors requires protection – minimum 50 cm in front of and 20 cm on both sides from the door’s edges. .
A base of an appropriate height should be made on the bottom of the chimney. It prevents air grate from being choked, allows discharge of condensate and helps to choose the height for gas flue connection. Base is recommended to be 25 cm high. It helps in proper cooperation between and the boiler and chimney. The base can be made of hallow brick and concrete, bricks or concrete only. .
Geometry of flue.
Doors should be oriented perpendicularly to the axis of the entry of gas connection. The minimum height of gas connection is 112 cm measuring from the chimney base to its exit. Changes are possible due to modification of the base height. Constructional height of the connection changes in 32 cm steps accordingly to the amount of segments used (112 cm, 148 cm, 184 cm, etc.) .
Junction of flue and chimney entry.
Due to different thermal expansion of steel flue and fireclay chimney entry expansion gap between the flue and entry has to be used to avoid any damages. Measurements and filling of the gap depend on the temperature of exhaust gases in the flue. For gas and oil boilers 2-3mm gap filled with elastic high temperature silicon is appropriate.
For fireplace inserts and boilers fired with solid fuels the gaps should be wider (about 5-10mm) and filled with fireproof material of constant flexibility (e.g.: ceramic cord). .
Finishing with clinkier.
In order to finish chimney with clinker board supporting the walling is necessary. The board must be made of concrete at least B20 (C15/20), with ribbed reinforcement Φ10 and Φ8 accordingly to the scheme below. After placing the concrete in a mould it has to be thicken to avoid pressure cracks. After 7 days the board has resistance of about 55-60%. Full resistance is achieved after 28 days. Maximum height of supported walling is 2,5 m. Ventilation of the gap (15 mm) between the shaft and walling should be provided by lack of filling in vertical welds in the first and last layer of bricks in the walling. Reinforcement of the board has to be minimum 2 cm away from its upper edge. Drips on the perimeter of the board should be made to avoid damp patches. The reinforcement must be approved by a qualified specialist. .
Our offer includes also prefabricated supporting boards for typical sets of flues. .
Gas flues have to be finished with use of a covering board. Our offer include boards for typical chimney sets. In case of using different set of flues the board should be prepared on the construction side including instructions for supporting boards. Drops discharging rainfall water should be made. Edges of the board should protrude 8,5 cm over the hallow brick or walling. Below an example of covering board for set of flues PK+2 x ventilating brick without walling. Treatment of flue gas vent is described in the instruction available on our website