A very important component in a ventilation plant is the air inlet. The function of the air inlet is to receive fresh outdoor air which is to be guided further to the ventilation plant. The air inlet is the front line defence of the ventilation plant against pollution and moisture from the outdoor air and therefore to the largest extent possible, should stop moisture, such as fog, drizzle and snow and additionally also larger pollution such as pollen, coarse dust, insects and leaves.

The expression air inlet does not only cover the inlet as such, but also the channel leading to the next component in a ventilation plant, the main filter. This is a part of the plant which is very exposed to moisture and pollutions and therefore should be given special attention. Care should be taken to provide the air inlet to be a collection area for moisture, dust and organic material as this may be unfortunate as to micro biological growth.

It therefore is a challenge to design the air inlet and the channel to the ventilation plant in such a way that moisture and snow do not penetrate to the plant. Precautions therefore have to be taken to ensure that inspection and cleaning of the air inlet and the channel as such can be performed correctly and frequently. This again means that the air inlet, the transfer channel and the filter of the ventilation plant as such, are made easily accessible.

Penetration of moisture through the air inlet and the channel into the ventilation plant will contribute to increasing the risk for undesired micro biological growth in the system. From the inlet to the filter there frequently will be many possibilities for deposit of dust from the outdoor air. Dust combined with moisture provided the best growth conditions for many microorganisms.

It is naturally especially large concentrations of dust in the filter. However, also the inlet channels will have large deposits of dust, dependent of the flow conditions in the channel as well as the procedures and routines for maintenance and cleaning. Another problem is the use of silencers arranged between the air inlet and the plant, thereby to reduce the noise from the plant as such. Such means very often are very little accessible for inspection and cleaning and additionally the sound absorbent binds more dust than a smooth surface.

Combined with the moisture penetrating into the above mentioned devices, there will be good conditions for undesired microorganisms. Blooming of undesired microorganisms may in worst case, lead to health damages, such as asthma, allergy and others for persons staying in the building as such.

Moisture which penetrates through an air inlet and which is not rapidly dried up or drained in a proper condition, may also have other consequences than the micro biological effects.

Such water penetrations also will contribute to increased risk for corrosion in the inlet channel and in the plant as such. Thereby the value and function of the entire plant may be decreased quicker than in dry conditions.

Another problem is that moisture leaking from the inlet channel will flow out in the building as such. This is very often difficult to discover and the consequence after a while may be apparently not understandable growth of undesired microbes with following negative health effects. Additionally such leakages may cause large damages to the building if not discovered and repaired quickly enough.

The air inlet with the channel to the plant according to the present invention ensures that the plant very easily can be inspected and maintained. This is achieved with the air inlet according to the invention as defined by the features stated in the claims.

The drawing discloses in figure 1 schematically a longitudinally section through a ventilation plant comprising an inlet screen with a coarse filter in front of a chamber solution with a main filter, figure 2 discloses in a perspective view the chamber solution of the ventilation plant, between the inlet screen and the plant as such and figure 3 discloses the components of the air inlet.

The air penetrates into the ventilation plant through an air inlet 1 and thereafter is guided into a service chamber 2 with a main filter 3. In the service chamber 2 the air is guided through the main filter 3 through a ventilation plant 4. The air inlet 1 comprises a prefilter, preferably of the amerkleen type, to stop moisture and pollutions. The prefilter preferably is of the type amerkleen m80. By making replacement of the prefilter in the air inlet 1 simple and easy and also carry out such replacement frequently, smelling from the filters is avoided resulting in that the main filter 3 as such need not to be replaced very frequently.

The service chamber 2 is air tight and clear and ensures that the air flowing through from the air inlet 1 to the main filter 3, makes the service work, such as replacement, cleaning etc. of the filter 5 in the filter cassette 9 of the ventilation plant, easy and quick. Depending on the need, the number of main filter 3 may be increased to achieve a lower pressure fall through the plant, the SFP-figure, possibly the number may be decreased as such work is made substantially easier as this is performed from and in the service chamber 2.

By constructing the screen in the air inlet 1 with a chamber solution where the coarse filtering is performed in the air inlet 1 and the finer filtering is performed in the main filter 3, both of which being arranged in the service chamber 2, the best possible filtering is achieved. By designing of the service chamber 2 it is ensured that cleaning and maintenance of the inlet channel is made very easy. The main filter 3 is replaced in a quick and safe manner. Furthermore the principle with a service chamber 2 between the air inlet 1 and the ventilation plant 4 provides good freedom of choice as to the degree of fineness in the filters and the filter surfaces.

The air inlet 1 comprises a number of filter cassettes 9, each of which being adapted to receive a perforated filter bottom 8 and a filter 5. A perforated a cover 6 holds the filter 5 in place against the filter bottom 8 in the filter cassettes 9, against the pressure from the air flow from below and up through the filter bottom 8, the filter 5 and the cover 6.

In case the air inlet should be used in areas with possibilities of snow and frost, heating elements 7 are installed suitably between the filter bottom 8 and the filter 5 in such a way that the heating element 7 which may be a heater cable having physical contact with and being secured to the filter bottom 8. The heating elements 7, respectively the heating cables heat the filter bottom 8 in such a way that ice which may have been created and snow which has been attached to the filter bottom 8, is melted. In this way is ensured that very little snow penetrates through the filter 5.

Between the filter cassettes 9 are arranged inclined plates 10 to guide the air from below through the filter bottom 8, through the filter 5 and into the service chamber 2.

The filter 5 is made of a glass material having a thickness of approximately 100 mm and as a coarse filter this will stop fog, drizzle and coarse dust. The filter 5 suitably is treated with an adhesive agent to capture the dust. To stop the coarse dust is important as this causes high pressure drop on the main filter and smell in the plant because the coarse dust allows mould fungus to thrive.

Installing of pressure sensors above the screen or the filter cassette 9 allows for registration in case of the filter 5 is blocked or freezes. At a pressure fall of approximately 250 Pa, the plant will be stopped and the heating elements 7 will be activated. Upon a shorter period of time such as 1/4 hour, the plant is free of ice and can be started again. In this period the ice will loosen and fall down on the inclined plates 10 and slide further down. The inclined plates 10 also keep water away from the filter bottom 8.

The air inlet 1 ensures that fog is prevented in entering the plant when the environment has a temperature below the freezing point and at least down to minus 25 °C.

Upon shorter shutdown of the plant for melting ice and snow, the plant can be placed in operation modus within a short period of time, such as up to a minute.