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Are Your Air Handling Units Spreading COVID-19?

5 October 2021

Air conditioning and air handling units are one of the most important and comprehensive systems onboard. Snaking around, covering all decks and spaces, these almost-invisible systems keep crew and guests air-conditioned and comfortable. From the whirring, thumping and buzzing compressors, through to the sea-water cooled heat exchangers and individual controls in each cabin - the technology in these systems is designed to keep the air onboard clean and safe. However, it is important to know if these onboard systems are spreading COVID-19 or any other airborne illness and, if there is anything we can do to be safer? 

The UK government recently released their COVID-19 sanitary recommendations for buildings but they don’t readily translate well to yachts. For example, their suggestion of regularly opening windows and increasing the flow of fresh air would be an Engineer’s worst nightmare and ultimately impossible.  

So, what potential upgrades to onboard AHU systems can keep crew and our guests safer?  

HEPA Filters

SARS/CoV-2 is a relatively ‘large’ virus, so installing a certified HEPA filter can block up to 99% of the virus particles from passing through your AHU system. But, it’s important to note that these filters have increased costs - not only do they come at an inflated purchase price, but to stop more particles than your standard AHU filter, they will need an increased level of regular changing. To overcome this, vessels can carry sand-changing filters onboard. This is an easy and non-invasive solution that requires no additional cost or time to modify as they slide straight in place of your regular filters. 

UV Lighting

Installing UV lamps on the AHU supply side can provide a 90% reduction in the generalised viral load, plus doubling the time in contact with the virus would increase the potential reduction to over 95%. The downside of adding UV lamps to existing AHU systems is that it is usually an invasive and costly method to retrofit to an already complicated system. However, it is a viable and good option for a new-build vessel.  

Local Applications 

Local applicants are the ‘go-to’s’ and standard minimum practice on superyachts. They act as disinfectants and, as an option, emit a fresh scent throughout the yacht. Applicants are applied directly in the AHU or locally within each plenum and come as gels and sprays. Gels sit in small pots or are spread in crucial areas, whereas sprays are applied directly in the baffles to keep the air circulating virus-free.  

Increased Maintenance  

A thoroughly clean and disinfection of the AHU system’s piping is recommended on a yearly basis and is usually done by external contractors during shipyard periods. The planned maintenance onboard usually calls for daily, weekly and monthly checks and, if issues are seen, corrective measures can be put into place to help prevent future problems. These checks, when done correctly, are very effective at maintaining the system at its designed optimum.  

It’s important to regularly check whether or not your AHU system needs an upgrade to the hardware or if changing your PMS will provide increased safety. Small changes can make big differences in the long term for the smooth and safe operation of your onboard system. 


Article author: Adrian Coetsee, PYA Director of Training (Engineering)

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