SIZING CHARTS

FOR BRANCHED COLLECTIVE FLUES (BCF)

Branched Collective Confluent System for "Type B" appliances

This System is indicated for natural draught boilers. Its structure is intended either inside a shaft of a multi-storey building (Type 1), or outside the building (model 2); in both cases, the boiler must be installed outside of the living space, since the combustion air for this type is provided by the surrounding environment. The sizing of the system, in any case, must be made in accordance with the Italian Standard UNI 10640 and is guaranteed for pressures up to 200 Pa for dry and wet operations.

Schematic outline for the sizing of a "Type B" Confluent System with a maximum number of 5+1

Boiler Output              Height of the System                               Diameter of the Main Duct                          Diameter of the Secondary Ducts          "No. of Connections"

19 KW
power developed about
16,000 Kcal / h

24 KW
power developed about
20,000 Kcal / h

27 KW
power developed about
23,000 Kcal / h

34 KW
power developed about
29,000 Kcal / h

Schematic outline showing the construction of a "TYPE B" BCF
for appliances with nominal output estimated between 20 and 24 kW

Type 1:
Schematically it consists of a single-skinned Main Duct, made of Stainless Steel AISI 316 5 Dc thick and Secondary Ducts confluent to it, made in Stainless Steel AISI 304 5 Dc thick, smaller in diameter than the main duct.
The Secondary Ducts have the function of collecting the flue gas coming from the individual appliances, to which they are connected through a 90° Tee, duly provided with a condensate drain.
The gas, thus collected, is conveyed to the Main Duct, through a 135° Tee, suitably reduced.
Each of the Secondary Ducts is equal to the height of an interstorey; the last boiler served does not connect to the Main Duct, but is autonomous and evacuates into the open atmosphere.
The Main Duct can have a base or intermediate start, but in any case must be equipped with an inspection chamber.
For flues adjacent to or intersecting living spaces, there should be an air shaft adequately ventilated. It is advisable to provide for the insulation of the system inside the shaft through the use of mineral wool for the Single Wall.

Type 2:
This type, schematically, is identical to the previous; it differs only for the Main Duct that is no longer installed in a shaft, but as a Twin Wall System installed on the outside of the building.
It is important, in both cases, that the number of boilers to be served must be in proportion to the actual dispersal capacity of the Main Duct, for which it is still recommended not to exceed five connections.
In the case of multi-storey buildings, in which the number of connections is increased to six, it is recommended that more branched collective flues be installed.

Collective Monoflow System
for "TYPE C" appliances

This system is suitable for roomsealed forced draught boilers; its construction is programmed either within a shaft of a multi-storey building or on the outside the building. In both cases, the installation of the boilers can also be done within the living space, but always in the proximity of a perimeter wall of the building, since the combustion air intake for this type is from the outside through a forced draught system. The sizing of the system must be made as required by Italian UNI 10641, and is guaranteed for pressures of up to 200 Pa for dry and wet operations.

Schematic sizing outline of a monoflow "Type C" System 
with a maximum number of 6

Boiler Output                            Height of System                       Diameter of the Main Duct                  Diameter of the Secondary Ducts                   "No. of Connections"

17 KW
power developed about
14,000 Kcal / h

26 KW
Power developed about
22,000 Kcal / h

34 KW
Power developed about
29,000 Kcal / h
 

Schematic outlines for the construction of a "TYPE C" BCF
for appliances with an estimated nominal output of between 20 and 24 kW

Type 1:
Schematically it consists of a single-skinned Main Duct, made of Stainless Steel AISI 316 5 Dc thick and Secondary Ducts confluent to it, made in Stainless Steel AISI 304 5 Dc thick, smaller in diameter than the main duct.
The Secondary Ducts have the function of collecting the flue gas coming from the individual appliances, to which they are connected through a 90° Tee, duly provided with a condensate drain.
The gas, thus collected, is conveyed to the Main Duct, through a 135° Tee, suitably reduced.
Each of the Secondary Ducts is equal to the height of an interstorey; the last boiler served does not connect to the Main Duct, but is autonomous and evacuates into the open atmosphere.
The Main Duct can have a base or intermediate start, but in any case must be equipped with an inspection chamber.
For flues adjacent to or intersecting living spaces, there should be an air shaft adequately ventilated. It is advisable to provide for the insulation of the system inside the shaft through the use of mineral wool for the Single Wall.

Type 2:
This type, schematically, is identical to the previous; it differs only for the Main Duct that is no longer installed in a shaft, but as a Twin Wall System installed on the outside of the building.
It is important, in both cases, that the number of boilers to be served must be in proportion to the actual dispersal capacity of the Main Duct, for which it is still recommended not to exceed six connections.
In the case of multi-storey buildings, in which the number of connections is more than six, it is recommended that more branched collective flues be installed.

In both cases, the correct installation of the system must be done by installing an inspection chamber at the base of the system and a flue gas analysis component over the 90° Tee at a distance equal to at least three times the diameter of the flue.

SINGLE USER CHIMNEY SYSTEM

This system is indicated for Open and Closed Fireplaces. It may be installed either inside a shaft (Type "A") or outside the building (Type "B").
For the correct installation of the Chimney System, it is important to install the appliance close to a perimeter wall.
The sizing of the system must be done in conformity with the regulations of the Italian UNI 10683.

Type "A":
Schematically it consists of a Vertical Chimney System, made of Stainless Steel AISI 316 5 Dc thick.
Following the exact sizing of the system, we recommend the appliance be connected to a 45 ° bend; at the point in which the system passes from indoors to outdoors, it is necessary to connect a 135° Tee.
This important measure, besides favoring an increase of pressure in the initial part of the system necessary to facilitate the rise of the flue gas, promotes drainage and the eventual collection of soot.
For flues adjacent to or passing through living space, a shaft adequately ventilated should be provided.

It is advisable to insulate the system inside the shaft using single wall mineral wool.

Type "B":
This type, schematically, is identical to the previous, differing only for the vertical section of the Chimney no longer installed in a shaft, but installed as a Twin Wall System on the outside of the building.

Design

The plan for a fireplace should follow some simple rules of proven validity:

1. the width, height and depth of the fireplace opening should be in the ratio of 6: 5: 4.

2. the height of the hood should be equal to that of the fireplace opening.

3. the height of the chimney system should be 10 to 15 times the height of the fireplace.

Sizing

The sizing of a Chimney System is carried out through the calculation of the area (expressed in m2) of the fireplace surface using the following formula:

                                                                                                                           S = (A + B) x H

The result is related to the effective height of the system in the Sizing Diagram. The intersection of these two axes coincides with the range of existence of the diameter that satisfies this condition.