Impianti e ricambi per il riscaldamento e il condizionamento di ambienti

Fan Heating Systems for Schools

If the Aerferrisi system in apartment buildings represents a progress in wellbeing, in schools it is an absolute necessity.

We certainly remember when, entering into a classroom that had already been crowded for a few hours, a disgusting smell would welcome us.

A gathering of kids closed in a classroom, as large as it may be, requires a change of air. It is not allowed anymore, under modern health regulations, to have gatherings of this kind without an artificially created correct air change that permits to stay and breathe in a room at tolerable conditions.

An average classroom of 100-120 cu m can host 25 to 30 students. For optimal conditions, each student needs 20-25 cu m of air each hour. The total air change, therefore, is 500-750 cu m/h, which corresponds to a volume change of about 5 vol/h.

Some studies indicate for school an air change of 2 vol/h. According to Aerferrisi’s technical service, this is absolutely insufficient.

It is moreover important that the delivered air is never recycled, to avoid the spreading of epidemic diseases. On the other hand, the heat technician knows that, with 5 changes available, the heating will easily be produced by the air, whose inlet temperature will have been increased so as to allow for the dispersed calories.

An example will better clarify this concept.

If a classroom is heated at 20°C, if the minimum temperature taken outside is 0°C, and if dispersions are 2000 cal/h, we have:

In principle, it can be established for the classroom previously taken as an example; delivery cu m/h 500; accidental replacement for dispersions, cu m/h 100; forced replacement cu m/h 400.

Therefore, by delivering into the classroom 500 cu m of air per hour at the temperature of 33°C taken at 0°C, a temperature of 20°C and 5 air changes will be obtained in the classroom, for a total heat absorption of 5000 cal/h.

Naturally, the delivered air must be expelled, and in order for this to happen, also an appropriate air extractor must be prepared, besides the air outlet.

The appliances that best correspond to the solution of this interesting and important problem are the Aerferrisi CP and CV series, and ES air extractors.

In designing a system of this kind, it could be interesting to consider the application of an air extractor also for the air change service in bathrooms, and the air delivery in classrooms should always be more than the extraction, in order to allow to form an overpressure that will eliminate the draughts of cold air and uncontrolled entry of cold external air.

The air taken from the outside must be sufficiently filtered. It is a good policy to use very suitable filters, changed regularly and at the right moment.

The air delivery and extraction machines must have a volume control device to allow to regulate the right level of air change. The humidification is not essential: the crowding itself produces a fair amount of humidity, which makes this a negligible factor if the thermal head with the outside does not exceed 20°C. If, on the other hand, that level is exceeded, we suggest to use heating units with humidification.

What has been described above also applies to gyms and meeting rooms.

The illustrated system is the most convenient, as only one unit treats one group of classrooms, but it is essential that these classrooms are all at a similar temperature level.

Where there is a double position of classrooms compared to external temperature conditions, it is necessary for each unit to independently service both groups.

In order to regulate the temperature inside the classrooms, the set delivery volume should not be modified, but one should act on mixing the water so as to reduce the heat input supplied by the coil of the distributing unit.

The reduction in volume of the air change can only take place in relation to environmental and health needs, and within limited amounts.


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