SOLZAIMA Pepper 70, Инструкция по эксплуатации

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4
4.1. Combustion Air and Gas Circulation
4.1.1. Theoretical notions for chimneys installations
There are some existing factors that can cause significant changes in the depression
created in your chimney and consequently on the smoke draft that will have on your
equipment.
The combustion created in your equipment, generally increases greatly the temperature
at the beginning of your chimney in view of the exterior temperature. This fact causes
low pressure in the inner part of your chimney (near the cooker) which conjugated with
a superior pressure on the outdoor air to chimney creates the strength that causes a
natural movement of the flue gases through the chimney flue, which we name of natural
draft or “chimney effect”, which also generates the inlet of air necessary for combustion
inside the stove. The taller your chimney is, the greater the difference of pressures and
therefore the greater the natural suction or chimney effect.
This effect has on its base a physical measuring that indicates that the minimum height
of the chimneys must not be inferior to 4 metres, in relation to an average altitude of the
land, to average ambient temperature differences, and to average temperatures of the
wood cooker functioning. However, this measurement is not compulsory, once there can
be chimneys functioning well with less height and other chimneys with superior height
functioning worse. In order to install efficient chimneys, the reasons for this
phenomenon must be understood. Beyond these geographic factors (altitude, exposure
to the sun, direction) and of atmosphere (rain, fog, snow) that influences the chimney
draft and it’s depression as well as the ability to draw the smoke from the stove, there is
still another factor to consider that in many cases is crucial – the wind.
In fact, the predominant wind (which depends many times on the land morphology and
house implanting zones) can cause many relevant changes to the depression created in a
chimney, that is, wind with a predominant arising flow, causes an increase of depression
on the chimney and that justifies better drafts. Contrary, a predominant descendant
wind causes decrease of the depression effects, which means that it eliminates the
capacity and extraction of chimneys. A predominant crosswind has an effect that
depends on how the chimney is installed.
For one to understand this effect, we can evince that a descendant wind at 45° with a
velocity of 8 m/s (on a wind beaufort scale from 0 (calm) to 12 (hurricane), corresponds
to a wind of 5 (fresh breeze) causes a pressure increase effect about 17 Pa, which can
eliminate the effect that a chimney has, for example a normal depression of 12 Pa.