How to Use the Air-conditioning System Correctly During the Normalized Epidemic(COVID-19)Prevention and Control Period?

Regarding the benefits of ventilation, we need to reiterate:

First of all, the ultraviolet rays in the sun have a strong killing effect on pathogens in the air. Opening windows for ventilation is conducive to air circulation and can dilute indoor harmful gases or germs. Therefore, opening windows for ventilation is the simplest, effective and economical way of indoor air disinfection.

Secondly, more ventilation can reduce the carbon dioxide produced by breathing in the room, increase the oxygen concentration, and keep the air fresh, thereby improving the body's immunity and preventing the occurrence of respiratory infectious diseases. Next, we will focus on four types of air conditioning systems:

01 All-air air conditioning system

An air-conditioning system in which the indoor load in the air-conditioning area is borne by the air that has been heated or cooled. Usually widely used in shopping malls, theaters, halls and other places that require high air quality.

[A] Preparation before opening:

1. Check whether the equipment is operating normally. 

2. Identify the source of fresh air and the fresh air intake and surrounding environment. 

3. Keep a certain distance between the fresh air intake and exhaust to avoid short circuit.

[B] Management and maintenance during operation:

1. Regularly clean, disinfect or replace cooling tower equipment and components, and Check the bathroom floor drain, U-tube water seal, etc.

2. Strengthen the sanitation management of contaminated areas such as ventilation and air conditioning system condensate and cooling water.

3. The return air should be closed in medium and high risk areas, and the doors and windows should not be completely closed when the air conditioner is running.

02 Fan coil and fresh air system

Heating places are mostly multi-story (or high-rise) multi-room buildings such as hotels, restaurants, apartments, hospitals, and office buildings.

[A] Preparation before opening:

1. Check whether the equipment is operating normally.

2. Identify the source of fresh air and the fresh air intake and surrounding environment.

3. The fresh air system is turned on 1h before the opening of the site and runs all day to ensure the normal operation of the exhaust system.

4. In rooms with large entrances and deepth, measures should be taken to ensure ventilation in the internal area. If the fresh air volume is insufficient (less than 30m3/h. per person required by the national standard), the personnel density should be reduced.

[B] Management and maintenance during operation:

1. Strengthen ventilation, open doors or windows when the air conditioner is running.

2. Strengthen the sanitation management of condensed water and cooling water in the air-conditioning system in easily polluted areas.

3. Regularly clean, disinfect or replace the cooling tower equipment and components, check the bathroom floor drain, U-tube water seal, etc.

03 Split type air conditioner

[A] Preparation before opening:

1. Clean the air conditioner casing and filter, and clean and disinfect the air conditioner heat exchaner when possible.

2. Check whether the air conditioner can operate normally.

[B] Management and maintenance during operation:

1. Open the windows and operate the air conditioner for a period of time before closing the doors and windows.

2. Intensify the number of ventilation and air exchange, and ventilate for 20-30 minutes every 2-3 hours.

04 Fan coil no fresh air system or multi-line system

[A] Preparation before opening:

1. Check each independent temperature control space to avoid taking back wind from the interconnected ceiling.

2. Clean the air conditioner shell and filter, and clean and disinfect the air conditioner heat exchanger when possible.

[B] Management and maintenance during operation:

1. Open the windows and operate the air conditioner for a period of time before closing the doors and windows.

2. Strengthen the frequency of ventilation, Ventilation for 20-30min every 2-3h operation.

When a confirmed case of new COVID-19, a suspected case, or an asymptomatic infection occurs, the following measures should be taken:

1. Immediately shut down the centralized air conditioning and ventilation system corresponding to the confirmed cases and suspected cases. 

2. Under the guidance of the local disease control department, the centralized air-conditioning and ventilation system in the above-mentioned area should be immediately disinfected and cleaned, and can only be reactivated after the hygiene inspection and evaluation are qualified.