COVID-19 and your fancoil. Are you at risk? Are there ways to mitigate the risk?
During the global pandemic of COVID-19 it has become a hot topic whether or not your HVAC system can cause risk of passing SARS-COV-2 through an airspace via fancoil units. The answer to the question is still unclear, but the general understanding is yes, it can. This article explains in detail the different ways of combatting airborne viral pathogens and their potential uses in residential HVAC systems.
A fan-motor pushes air through your suite with heating or cooling, depending on the season. It is known that SARS-COV-2 is transmitted from person-to-person via droplets of water from breathing or sneezing. If an infected person is in an airspace with an activated fan-motor, it is possible that SARS-COV-2 can be pushed into the airspace via the ducts. However, the real understanding is not that simple.
SARS-COV-2 is not known to fly through the air by itself. While the virus is tiny at 0.1-0.3 micron in size, it travels via water droplets which are much larger (10-1000 micron). This is why we wear masks, even cloth masks. The reduction of transmission is achieved by catching the large water droplets (known as infectious aerosols) and then ensuring that the filtration device is then regularly and safely disposed of.
FILTERS
Your fancoil filter is the first line of defense in capturing SARS-COV-2. A standard MERV8 rated filter will reduce SARS-COV-2 transmission up to 70% by capturing 3-10 micron size particles it in the filter. If your filters are regularly changed and disposed of safely, you can reduce the transmission rates from the fancoil air supply. However it is important to note that this does not change the dynamics of person-to-person transmission inside a room. If an infected person sneezes in a room with someone else, the fancoil will not have the ability to remove the virus from the air before it is directly received by other people. You read more information on the ASHRAE page about MERV filtration. Please note their recommendation of using a MERV13 filter is impractical. The reduced pore size of this filter will choke the fan-motor reducing it’s life span. In newer fancoil units using brushless digital motors, there will be an increase of ramping noise where the fan works harder to overcome the obstruction of air flow introduced by the filter. We recommend a MERV8 filter to be changed regularly. The frequency is dependent on whom you invite into your suite. If you isolate, and limit non-household guests to a minimum, we believe you can change filters minimum twice per year as usual. General recommendation states that filters should be changed quarterly.
UV LIGHTS
UV lights are commonly reported as a means to de-activate SARS-COV-2 (not the same as killing or destroying). It does this by interrupting the genetic code of the virus and prevents it from being able to infect a recipient. However, it is very important to understand that UV light research suggesting this, and many products on the market are not the same thing. When a UV light is put in an HVAC system, the critical factors to consider are the strength of the light versus the speed the air travels by the light. In some rough calculations based on research papers, we determined that a 600CFM fancoil unit requires a light strength of 13,000 watts which is simply impractical. If someone is trying to sell you a UV light, you must consider the airflow volume versus the power of the light. Do not buy a UV light for your fancoil and believe it is protecting you from having COVID positive people in your house. Again as mentioned above, person-to-person transmission in a room is not mitigated with a fancoil UV light. The air must by cycled through the room many times. At very best, a fancoil UV light will minimize the ability to transmit SARS-COV-2 from one room to another. Another important note is that UV light is only feasible to deactivate SARS-COV-2 in water or air, and cannot be effective in sanitizing any kind of porous surface. If you watched the Grey’s Anatomy episode where Bailey has her masks hung in front of a strong UV light, this is complete false. A mask contains layers of fibres, and a single photon of light can only affect the surface it hits. Light cannot pass around corners and permeate into the fibres of a mask.
BI-POLAR IONIZATION
Bi-polar ionization is a device which emits ion particles of different charges. It is well known that negative ions can improve mood, sleep and reduce dust in the air. While research has shown positive results that ionization can combat SARS-COV-2, it is important to understand how it works. Ions emitted into the air will bind with particles such as dust, mold, bacteria, and viruses. The ion binds with the particle and causes it to stick to a surface with an opposite charge, such as walls, carpets, curtains, and furniture. It is not fully established yet if ionization actually kills SARS-COV-2. Secondly and similar to UV lighting, the air flow volume is an important consideration. The presence of ions may not be great enough to reduce or remove the threat of re-transmission within an enclosed airspace. It also, again, does not solve the problem of person-to-person transmission inside a room.
AEROSOLIZED HYDROGEN PEROXIDE
So far this is the most studied and approved method for industrial combat of COVID-19. Moving air is injected with hydrogen peroxide as a mist which effectively kills SARS-COV-2. However the machinery is expensive and requires regular maintenance and upkeep. So far this is the most effective method for hospitals and industry that can afford the equipment. We do not have knowledge of a consumer unit which is affordable and easily maintained.
OZONATION
Ozone is well known for being the protective layer in the earth’s atmosphere that shields solar radiation from seriously harming life on the surface. You may remember in the 1980s a global treaty was signed to stop using certain aerosol propellants (CFCs and HFCs) in spray cans which were linked with the weakening of the earth’s ozone layer (in the stratosphere). Ozone is O3, which is produced when an electrical charge passes through air, most commonly lightning. The electrical charge causes oxygen (O2) particles to split and then bind together as 3 molecules (hence O3). That third molecule is very unstable and want to separate from the bond. It does this by binding with small particles such as dust, other gasses, and in this useful case, viruses. Ozone has been proven as an effective way to sterilize rooms plagued by infectious molds, and is being researched by the US and Canadian Environmental Protection Agency (EPA) as a means to disinfect personal protective equipment (PPE) on the front lines. When putting a mask in a box and introducing O3 above 10 parts per million (PPM), it has been found to effectively sterilize porous surfaces because Ozone is a gas, and can permeate all parts of the surface. However there is a serious caveat. Ozone is dangerous to your health. When O3 breaks apart again, the third particle tends to bind with free chlorine molecules in the atmosphere to create chlorine monoxide, leaving the normal O2 particles behind. This chlorine monoxide is hazardous to your health and anyone who has felt a scratch feeling in their throat in the presence of high levels of ozone are reacting to the chlorine gas. Therefore use of Ozone in a fancoil unit is a very bad idea. Ozone is also known to react with substances such as rubber shielding on wires, and closed cell foam which is in the fancoil. The ozone will react and cause the materials to become brittle and fall apart.
CONCLUSION
Here at JPS we are researching products and using our “spidey sense” from experience to determine if there are any products which can help us all fight the pandemic in our residences. We encourage all consumers to be wary of solutions on the market which make guarantees. In short, there is no guarantee a single product fixes any problem. We do not subscribe in the rush to put products on the market without rigorous testing.