Can central air conditioning also spread viruses?

Will the use of central air conditioning cause communication risks? Shi Xiaoming, director of the Environment Institute of China CDC, said at the press conference held by the joint prevention and control mechanism in the State Council this afternoon that if the virus cannot be completely prevented from spreading through the ventilation system only by using the central air conditioner, there is a certain risk. But in order to control this risk, we should pay attention to three aspects:

First, before turning on the air conditioner, that is, before using the air conditioner, it is necessary to check whether these devices are normal and whether the air inlet and the air outlet are kept at a certain distance. The cooling tower should be cleaned to keep the fresh air outlet clean.

Secondly, it is unrealistic to try to increase the fresh air volume and reduce the return air during operation, so we suggest that the return air should be lowered as much as possible to increase the fresh air volume.

Third, strengthen the sanitary management of cooling water and condensed water, and regularly clean, disinfect or replace equipment and components such as air supply outlets. This is the general situation. Of course, if there is a case of COVID-19 in this place, the central air conditioner will have to be cleaned and disinfected, and it will have to undergo hygienic evaluation before it can be reused.

Regarding cooling water and condensed water, Shi Xiaoming said that these are different types of central air-conditioning systems, some of which do not produce cooling water and condensed water, mainly some multi-connected air-conditioning systems, and one outdoor unit connects several indoor units. In this case, the cold enzyme refrigerant is used for cooling or heating. Therefore, during the operation of the air conditioning system, no cooling water and condensate water will be generated.

In this process, it is necessary to strengthen the cleaning, disinfection or replacement of equipment such as air supply outlets. Why should the sanitary management of condensed water and cooling water be strengthened? Condensed water is mainly produced in air handling devices and surface coolers of fan coils. If these parts grow long, microorganisms will easily breed, affect indoor air quality, or have some potential risks. Therefore, the condenser should be cleaned and disinfected regularly.