Ask the Chemist - Breathing healthy air: what and how to clean A/C systems?
Air conditioning maintenance is an activity often underestimated. Why? Certainly, it depends on the absence of a legislative obligation (which instead exists for boilers, cars, etc.) and the lack of education of individuals on the subject. Yet, air conditioning systems have a very important function in our buildings: that of supplying and circulating the air we breathe. Indoor Air Quality (i.e. the air quality within and around buildings and structures) is a concept that has been discussed at length in recent months, a condition that everyone can and should monitor, regardless of the current pandemic, as stated by BESA in the Beginner’s Guide to Indoor Air Quality. Not only viruses but also bacteria, mould, and mites: air conditioners are humid environments where these types of microorganisms inevitably tend to proliferate and whose presence can cause various types of illness and allergies to occupants who breathe them. Living, working and spending leisure time in a clean and healthy environment is everyone’s priority, but for this to be possible it is necessary to carry out regular cleaning and maintenance of A/C systems. We interviewed Dr. Paolo Mattavelli, R&D manager of Errecom, to find out more about this topic. What needs to be cleaned? How often? Here is what we found out.
1) Why is it so important to clean air conditioning systems?
There are several reasons. First of all, regularly cleaning your air conditioner is fundamental to guarantee a high quality of the air released into the environment. During the last year, we’ve discussed extensively Indoor Air Quality as a fundamental requirement not only to minimise the risk of spreading bacteria, germs, and viruses in confined environments (such as private homes but also offices, schools, public transportation, etc.) but also as an indispensable element for the quality of life. Just think that we spend 90% of our time indoors and research has shown that poor air quality harms the ability to concentrate with inevitable consequences on productivity. Therefore, deep cleaning of your A/C systems means healthy air: necessary for people’s health and their quality of life. Also, remember that not properly clean A/C systems will consume more energy, which inevitably means higher bills. Finally, dirt, deposits, and encrustations that are not properly treated can cause premature failure of the A/C system, reducing its average life.
2) Concerning indoor air quality, what are the risks we face if we do not clean our A/C system?
Poor maintenance of air conditioning systems increases the risk of contracting various diseases. Infectious agents (bacteria or viruses) and allergens (mould or mites) can be found in the filters and, more generally, in the indoor units of A/C systems and the problem is that they can seriously be harmful to human health. One example is legionella pneumophila, a bacterium that tends to proliferate in air conditioners that are not properly sanitised. It is responsible for respiratory disorders that can even lead to severe pneumonia. Other examples could be conjunctivitis, caused by the transport of bacterial and/or viral agents in the air, and allergic reactions, caused by dust or mould in air conditioning evaporators. On the contrary, if properly maintained and cleaned, air conditioners can be useful and even healthy for some allergy sufferers. For example, in areas where humidity is high, the air conditioner dries the air out, reducing the growth of dust mites, with obvious benefits for allergy sufferers. In areas where air pollution is particularly high, instead, filters trap harmful agents, improving the respiratory conditions of asthmatics.
3) It happens sometimes that an unpleasant smell is perceived when the a/c system is switched on, especially in cars. Does it depend on the proliferation of bacteria, mould, and other contaminating microorganisms in the ventilation ducts?
Exactly! This unpleasant smell comes out all the A/C systems that have not been properly cleaned and sanitised, and is linked to the presence of bacteria, mould, and germs that have accumulated over time in the ventilation ducts. Obviously, the smell is more intense in cars, as the passenger compartment is a more restricted interior than the one of a house or office, but the situation is the same even if the olfactory perception is lower. Further worsening the risk of contagion in cars is the fact that the A/C vents are orientated directly at the driver’s and passengers’ faces and that the exposure time to this contaminated airflow is constant and protracted over time.
4) Let’s talk about efficiency. Why does a clean air conditioning system consume less energy?
Untreated dirt deposited inside A/C systems, on filters, finned coils, etc., creates a sort of barrier that prevents heat transfer and reduces heat exchange. To reach the pre-set temperature, the system consumes more energy, which, of course, means higher bills for the consumer. Besides, if intense, dirt can block the air vents, causing a drastic reduction in the efficiency of the system.
5) Are cleanser and hot water enough to clean A/C filters?
No, they’re not. Although it is a widespread practice, simply cleaning the filters with cleanser and hot water is not enough. For a deep and complete purification of the A/C filters, it is necessary to eliminate germs and bacteria, which are responsible for the diseases I mentioned earlier. For this purpose, specific purifying and disinfecting products are needed to avoid damaging the A/C filters.
6) Cleaning the A/C filters: is it enough to state that an A/C system is clean?
No, cleaning filters is not enough. For sure A/C filters are a receptacle for viruses, germs, bacteria, dust, etc., but they are not the only part of the system that can be contaminated. Greasy dirt, organic residues, and microorganisms can also be deposited on the finned coils, not to mention the proliferation of mould that particularly affects the exhaust and condensate pump. This is an absolutely physiological condition: the indoor units of air conditioning systems are humid environments where germs and bacteria naturally proliferate. To overcome the problem, it is sufficient to proceed with regular cleaning operations: only in this way A/C systems can guarantee healthy air. To conclude, I would like to make one last remark regarding the cleaning of condensers, which tends to be even more underestimated as they are located outside buildings. In this case, external agents are the problem: leaves, smog, sand, dust, etc. Their accumulation could affect the performance of the condenser.
7) Who should take care of these cleaning operations? Can they be carried out by individuals or is it necessary to rely on the expertise and skills of HVAC technicians?
Only a technician can carry out a complete and thorough cleaning of air conditioning systems. Instead, with regard to routine cleaning operations that should be carried out frequently to ensure healthy air in the buildings, individuals can take care of them. There are in fact products, especially in aerosol cans, which are easy to use and safe for both the operator and the system. What I recommend is to always and only rely on specific, high-quality products, and to follow the instructions on the technical file and MSDS.
8) How often do you think it is necessary to clean an air conditioning system?
The answer depends on the intensity of use of the A/C system and the location in which it is installed, which may be particularly oxidising or dirty. As a general rule, I’d advise at least twice a year, to guarantee a complete and professional cleaning of the A/C system. In spring, before switching it on, to prevent dust and germs deposited over time from being released into the air. And after summer, once the hot season is over, to prevent dirt accumulated over the months from encrusting the surfaces, risking damaging the A/C system. In the case of heat pumps, I recommend cleaning them every time you switch from heating to cooling mode or vice versa. As far as the simple cleaning of the filters is concerned, which can also be carried out by the individual without the need for the technician’s intervention, I recommend a monthly frequency, always recommending the use of specific purifying cleaners and, especially during this period, the use of a disinfectant to eliminate any viruses.
9) Do you have any other useful tips for our readers?
I believe that all the information provided so far is exhaustive. But in case our readers have further doubts or questions, ERRECOM’s guidelines for the proper cleaning of A/C systems can be downloaded here for free.
