Operating air handling and ventilation units
Important information during the coronavirus pandemic

In light of coronavirus, operators of air handling and ventilation units are facing many questions about the operation and maintenance of their systems. We would like to address the key points here in brief.

It is important to note the following: COVID-19 is primarily transmitted through droplets. The possibility of airborne transmission depends on various factors, such as the virus concentration per droplet, time spent in the air, temperature and humidity.

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Servicing air handling and ventilation appliances is particularly important just now. Servicing will enable you to operate your air handling and ventilation systems without any health or hygiene concerns, particularly under current coronavirus conditions. That’s why we recommend servicing at your earliest convenience, including cleaning and filter replacement.

Contact your advisor now and schedule a servicing appointment.

Frequently asked questions

Do air handling and ventilation systems encourage the spread of coronavirus?

There is currently no evidence to suggest that coronavirus can be spread through air handling and ventilation systems. Indeed, experts agree that good ventilation of indoor areas helps to keep the risk of infection down.

In addition to systems being technically up to date and planned and installed correctly, they must also be operated properly and serviced regularly for operation to be safe and hygienic. Where these points are carefully followed, air handling and ventilation systems pose no increased risk of infection according to the experts.

What impact does the use of filters have?

As to the question of whether coronavirus can be filtered out using ventilation system filters, the first point to bear in mind is the size of viruses. Unlike bacteria, which, measuring 1-10µm are relatively large and can therefore be separated out efficiently by ePM1 fine dust filters, viruses are significantly smaller. The coronavirus measures approximately 0.16µm.

Having said that, viruses are generally attached to aerosols or dust particles. Transmission is primarily via droplets. Droplets that people produce are 0.5 to approx. 15µm in size. From other viruses it is known that a 1µm-droplet can contain a sufficient virus concentration to trigger an infection.

ePM1 filters separate out particles and aerosols, i.e. including droplets, down to a size of 1µm, depending on the separation efficiency. With higher separation efficiency, more of these droplets are separated out and thus remain in the filter medium.

When filters are replaced during servicing, personal protective equipment (PPE) should therefore always be worn. This is true irrespective of the current COVID-19 pandemic, as it is generally unknown what substances have been collected in the filter.

What are the key points to remember regarding operation and maintenance?

For the operation of air handling and ventilation systems during the COVID-19 pandemic, recommendations have been issued in a joint communication by the BTGA (Federal Industry Association for Technical Building Installations and Services), FGK (Association for Building and Indoor Air Quality) and RLT-Herstellerverband e.V. (AHU Manufacturers Association).

Fundamentally, continued good ventilation of indoor spaces is recommended, including in the current situation. Relative room air humidity should be between 30 per cent and 65 per cent. If the air humidity is too low, the sensitive mucous membranes in the upper airway are impaired, becoming more susceptible to viruses.

Recommendations for operating air handling and ventilation systems

  • Do not switch off air handling and ventilation systems that use outdoor air. Do not reduce volume flows of outdoor air.
  • Reduce the amount of recirculated air – if used by the systems – in favour of more outdoor air (fresh air). If possible, operate the systems with 100 per cent fresh outdoor air.
  • Extend system operating times before and after regular use where possible.
  • Secondary air units (fan coil units, induction units) are only effective in one individual room. They do not transfer air into other rooms.
  • Any servicing that is due should be undertaken now and maintenance intervals should be shortened, particularly with regard to filter replacement and hygiene inspections.