M/h.

When the supply ventilation is bought, it is important to take into account the most important characteristic — this is performance. So, when buying a system for an apartment with one or two rooms, it is best to choose a performance indicator up to 300 kb. M/h. If the apartment has four or three rooms, the choice should be stopped on models, the manufacturer of which is measured about 400 kb. M/h. Another characteristic is static pressure. If there are 2-3 rooms in the apartment, this characteristic should be about 450 PA. So that the functioning of the system does not imply the formation of noise, it is important to pay attention to such a characteristic when the device functioning as a level of formed noise. The optimal indicator in that case is possible if such an element of a system as a noise muffler will have a length starting from 850 — 900 mm.