- It must have rectangular cross-sections with 1.5 maximum ratio between the sides;
- If the flue is installed externally or in a cool room (e.g. stove room), it is absolutely necessary that
it is insulated so as to prevent cooling of the flue gas and condensate build-up;
- Elements of non-combustible materials - capable of withstanding combustion products and their potential
condensation - must be used for mounting the flue gas pipes (for the section from the device to the flue
inlet);
- It is forbidden to use fibre cement pipes to connect the devices to the flue;
- Flue pipes must not pass through rooms in which the installation of combustion devices is prohibited;
- The assembly of flue pipes must guarantee adequate sealing of flue gases during low pressure operation
of the device;
- The assembly of horizontal sections is forbidden
- It is prohibited to use countersloping elements;
- The flue gas pipe must allow the recovery of soot or be cleanable, and must have a constant cross-
section;
- It is forbidden to allow other air intake conduits and plant pipes to transit inside the flue gas pipes, even if
over-sized.
The stack is the end section of the flue, and is used to facilitate dispersion of combustion by-products.
It must satisfy the following requirements:
- It must have a usable outlet cross-section no less than double that of the flue on which it is inserted;
- In must be shaped in such a way as to prevent rainwater and snow from seeping into the flue;
- It must be built in such a way as to ensure the discharge of combustion by-products even in case of winds
from every direction and with any inclination.
The outlet height (where height refers to the top of the flue, regardless of any stacks) must be outside of the
so-called reflux zone, in order to prevent the formation of counter-pressures preventing the free discharge of
combustion by-products into the atmosphere.
It is therefore necessary that the minimum heights - indicated in the following figures - are observed:
Dista nce > 5 m
Technical
volume
;
Dista nce < 5 m
10
Distanc e> 1,85 m
Distanc e< 1,85 m
Reflow zone