Designing of ventilation, air-conditioning and heating systems

The design of ventilation, air conditioning and heating systems is regulated by SNiP 2.04.05-91. In accordance with the principles of construction, design decisions should not:

• violate the purity of air;
• create excessive noise or vibration in the premises, in particular, at the installation site, the noise level should not exceed 110 dBA;
• be fire hazardous.

In addition, the design of ventilation systemsand heating should provide for the maintainability of the equipment. This may surprise the owners of private cottages, but typical project documentation includes the calculation of the number of personnel who must operate the equipment. Otherwise, everything is quite obvious: the presence of corrosive media in the air ducts requires corrosion resistance from pipelines and ducts, and hot surfaces are inevitably isolated, what the idea of ​​fire safety, already mentioned above, is realized. If the insulation does not help to reduce the temperature of some sections of the projected system to a safe one, then it is strictly forbidden to place them in rooms where flammable aerosols or gases are possible. And such premises should be taken into account separately, performing the design of ventilation systems. Any non-standard elements of the system should be made of materials approved for use in construction.

General calculation for the premises where people work, is conducted:

• Summer - based on the maximum allowablerules of temperature in the premises with the formation of excess heat. In the absence of such an economically feasible temperature is selected from the permitted range. Estimated data are indicated in the annexes, and here everything is not so obvious. The temperature can not exceed 28 ° C, but at lower values, the environment starts to vary accordingly. The design of air conditioning and ventilation systems is aimed at fulfilling the above requirements.
• In the winter - based on the economic feasibility of maintaining in the room of a particular temperature within the permissible range. With a minimum temperature is simpler, it should not be below 14 ° C.

In this case, the flow velocity and relative humidity are also selected from a number of acceptable values.

For fully automated premises where people are not permanently, the rules prescribe a slightly different approach:

• In warm weather, operation atair temperature equal to the outside, and if there is an excess of heat in the room, the design of ventilation systems should make it its job to force the temperature difference to 4 degrees. In this case, the temperature in the room should not be lower than 29 ° C, otherwise the difference in temperature inside and out can be ignored. These conditions are correct, unless additional heating of air is required.
• In the cold period, if there is no excess of heat,it is necessary to maintain a temperature of 10 ° C, if there are excess heat, the design of ventilation systems should be aimed at maintaining an economically feasible temperature.

Climatic operating conditions should be taken according to the application of SNIP II-3-79.

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