Impianti e ricambi per il riscaldamento e il condizionamento di ambienti

Fan Heating Systems for Swimming Pools

In winter, to enable the continuation of water sports, or for spa treatments, it is essential to have sports facilities like indoor swimming pools. So it becomes very important to treat particularly the air in the closed environment, in order to avoid an excessive concentration of humidity due to the natural evaporation of water from the surface of the pool. The system has to be able to eliminate the mist, to avoid the dripping of condensation, and to create the conditions for the wellbeing of users and spectators. Furthermore, it is essential to keep a sufficiently high temperature, given the peculiar conditions of the users’ clothing. The hygrometric degree that has to be kept must be such as to avoid the condensation of water vapor against glass walls and windows and against the walls, as well as to diminish at the same time the state of unavoidable unease that excessive humidity causes to users. The internal temperature can be fixed at 25 – 27°, while the hygrometric degree must depend on the external temperature. The experience of Aerferrisi’s technical service establishes the conditions in the following ratios:

Te = -20° / internal hygrometric % 28
Te = -15° / internal hygrometric % 33
Te = -10° / internal hygrometric % 40
Te = - 5° / internal hygrometric % 45
Te = - 0° / internal hygrometric % 50
Te = + 5° / internal hygrometric % 60

The quantity of water evaporated from the surface of the pool depends on the temperature of the environment, its hygrometric degree, and of course on water temperature. If the water temperature is going to be set at 27°C, its evaporation in degrees/sq m/h will be set as:

Room hygrometric degree % 60% degrees/sq m/h 350
Room hygrometric degree % 50% degrees/sq m/h 460
Room hygrometric degree % 45% degrees/sq m/h 510
Room hygrometric degree % 40% degrees/sq m/h 550
Room hygrometric degree % 33% degrees/sq m/h 590
Room hygrometric degree % 28% degrees/sq m/h 680

Setting these values with reference to the swimming pool surface, one can know how much water vapor must be expelled, or better yet, absorbed. In fact, it will be the change of heated air that will create the premises for the desired environmental conditions. The air taken from outside, heated and delivered, will absorb the vapor in excess from the air.

Every cu m of air taken from the outside will be able to absorb, in order to bring the environment to the desired hygrometric degree, 4-5 degrees of water vapor at whatever temperature it is taken from outside, as there is a relative correspondence with the internal hygrometric conditions, and this amount of absorbed water vapor remains fixed at the above-mentioned conditions. The ratio between the total hourly evaporation and the absorbing power of the air will fix the amount of replacement air to be let in, and that is:

Q = P / ( 4/5 ) = cu m of air per hour

considering P as the total weight in grams of the evaporated water from the pool. The calories to use for the operation will be:

Cal/h = Q x ( 25/27 - Te ) x 0,3

The temperature of delivered air must correspond to the environmental temperature (25/27). The dispersion calories must be added to the above indicated calories. The air will thus be delivered at a higher temperature considering that it will give out calories due to dispersion. This excess temperature will be:

( Cal/dis ) / ( Q x 0,3 ) = °C Td

and therefore the final temperature of delivery will be:

Td + ( 25/27 )

An equal portion of expelled air must correspond to this delivered air. It is convenient to create a slight overpressure and consider the accidental losses due to infiltration from doors and windows and for the openings at the entrances. The mechanically expelled air, compared to the delivered air, will be:

Qe = 0,8 Q

It is evident that temperatures must be regulated according to changing conditions. Therefore, it is essential to apply the devices with volume regulation on the inlet and expulsion fans. Aerferrisi uses for these systems heating units of the CP, CV, or even AE series. The technical office is always available for free to anyone who has doubts or an entire project to submit to us.


Aerferrisi srl   Via Vittime di Bologna, 14 - 10156 Torino - Tel. 011/2740283 Fax 011/2740284   P.I. 00501690010