1. The distance between the air supply and exhaust outlets should be appropriate
Keep a distance of at least 3 meters between the exhaust vent and the air supply vent to prevent short circuits in the air flow.

2. Choose the right damper
In principle, the system air pressure balance error is within 10%-15%. It is not necessary to have a regulating valve, but in fact it is very difficult to adjust the air pressure only by the size of the air pipe. Therefore, it is necessary to set up an air volume regulating valve. Make adjustments.
① The air volume regulating valve should be installed at the branch of the air pipe. A three-way regulating valve can be installed at the three-way branch, or a regulating valve can be installed at the branch.
②The loop that is obviously unfavorable may not be equipped with a regulating valve to reduce resistance loss.
③The fire control valve can be used to replace the control valve at the place where the fire valve is needed.
④The louver tuyere at the air outlet should be the louver with a regulating valve. If the requirement is not high, a double louver tuyere can be used, and the air volume can be adjusted by adjusting the angle of the tuyere.
⑤ A damper that can be opened and closed should be installed at the fresh air inlet. In severe cold areas, a heat-preserving damper should be installed. When there is automatic control, an electric damper should be used.

3. The layout of the duct
① To minimize local resistance, that is, reduce the number of elbows, tees, and reducers
②The radius of curvature of the center of the elbow should not be less than the diameter or side length of the duct, generally 1.25 times the diameter or side length can be used
③In order to facilitate the adjustment of the air duct system, pressure measuring holes should be reserved before and after the branch point of the main pipe. The distance between the pressure measuring hole and the front partial pipe should be greater than 5b (b is the long side of the rectangular duct or the diameter of the circular duct), and the distance from the rear partial pipe should not be less than 2b. The pipe section where the airflow is relatively stable at the outlet of the ventilator should be reserved for pressure measuring holes.

4. Fresh air inlet location
① The air inlet should be located in a place with relatively clean outdoor air to ensure air quality
②It should be installed on the north wall, avoid on the roof and the west wall, and should be installed in the shade of the building so that the outdoor air temperature in summer can be lowered.
③The distance between the bottom of the air inlet and the outdoor ground should not be less than two meters. When the air inlet is arranged in a green area, it should not be less than one meter.
④ It should be arranged on the upwind side of the exhaust outlet as far as possible, and lower than the exhaust outlet, and try to keep a distance of not less than 10 meters