In houses of old construction the mechanical ventilation of air in rooms was provided in the most natural, simple and available way – through slots in window frames, leaky closed doors, hatches and so forth. Use of the modern heatpreserving technologies and construction materials makes impossible such air exchange therefore in modern buildings for ventilation forced-air and exhaust systems with recovery are used.
As the forced-air and exhaust system works with recovery
In today's realities when air, not only in the city, but also in suburbs where there pass noisy highways, is very polluted, the ventilation systems can be seen both in apartment, and in owner-occupied dwellings. Its installation needs to be considered at the earliest stage of construction – even at design.
The initial point of any system of the plenum ventilation is the exhaust grid on house facade from which there is air duct. Air pumps and fans carry out air supply to rooms of the house, and stretchers at the same time delete from them exhaust air. Usually exhaust fans and devices are installed in bathrooms, bathrooms and kitchens. There is air exchange at which cold air comes to the house outside, and warm, fulfilled is removed via the deflector installed on roof.
Use of recuperators allows to increase overall performance of ventilation system by 70% and to cut almost twice consumption of the electric power necessary for heating of the arriving air.
It is necessary to tell that the system of supply and exhaust ventilation in itself rather expensive and, besides, its operation also costs "kopek". The recuperator which is built in it allows to lower significantly expenses as does unnecessary constant use of the heaters heating the cold air arriving from the street. The recuperator is the camera with fans separated into two parts by thin aluminum or polypropylene plate. Fresh cold air comes to one compartment of this camera, and towards to it the stream of warm air which is already removed by system outside moves. In the recuperator there is heat exchange and heating of cold air, and heaters are used only for additional heating in cold season.
How to prevent frosting-up of the recuperator
It would seem, everything is good, but there is threat of frosting-up of the recuperator at which on its plates ice can be formed and gradually cork canals across which there passes air. Such situation arises when exhaust air is cooled arriving to value below of dew point if temperature on the street is significantly less than 0th OS. If not to take any measures, the forced-air and exhaust ventilation system will be able to resume work only after the air arriving outside reaches above-zero temperature. To avoid similar, in the forced-air and exhaust installations equipped with heat recuperators several engineering decisions are implemented. In them the electric heater which is warming up the arriving air to those temperature values when condensate and ice are not formed can be built in. But the most reliable and economical is use of electronic system of defrosting which work can be tied to several parameters. It can be the certain date determined for the specific region since which it is necessary to warm up the arriving air, or the set value of its temperature can be such parameter. In these cases operation of the recuperator will be organized cyclically: some time it works at the same time for entrance and for exit, then the supply fan is switched-off and the recuperator gets warm the warm air arriving via the exhaust fan. Such cyclic operating mode is supported by automatic equipment all that period, when necessary.
Application of forced-air and exhaust systems with recovery
Forced-air and exhaust systems with recovery represent monoblock designs which fans, air filters of thin and rough cleaning, heaters, warm and sound insulators enter. These systems provide air exchange without recirculation, i.e. the exhaust air does not come back to rooms, they make purification of the air arriving from the street and its heating to comfortable temperature.
Calculation of necessary power of system of aeration is made taking into account existing rules for residential units and constructions – on each square meter of the room 2-5 cubic meters of air an hour are necessary.
Installation of similar systems is reasonable in buildings and rooms where windows are closed hermetically, they are used for ventilation of apartments, offices, cinema and concert halls, industrial bakeries, converter shops and so forth. Use of similar systems in country houses and cottages is complicated by the choice of the location for this purpose of rather bulky equipment. If there is no opportunity to allocate for it the certain room on the first floor where there is kitchen, laundry and bathrooms, the system can be installed in the protected place of the basement or the first floor and also on the attic. In these cases you will need to take care of thermal insulation of the bringing and removing pipes and the equipment to prevent formation of condensate which can lead to damage of this expensive system.