--- title: How to optimise air handling units for healthy indoor climate – COVID-19 recommendations description: With our top three advise for air handling units – regular maintenance, high flow rates, minimised return air – we can optimise operation and maintain a healthy indoor climate. image: https://blog.swegon.com/hubfs/ahusocial.png --- [![](https://www.swegon.com/Static/img/logo.svg?v=3)](https://www.swegon.com/) Menu - [Solutions & services](https://www.swegon.com/solutions-and-services/) - [Products](https://www.swegon.com/products/) - [References & Insights](https://www.swegon.com/references-and-insights/) - [Support & software](https://www.swegon.com/support/) - [Sustainability](https://www.swegon.com/sustainability/) - [Why Swegon?](https://www.swegon.com/why-swegon/) - [Product Search](https://www.swegon.com/product-search-result/) - [Document Search](https://www.swegon.com/support/find-documents/) - [Career](https://www.swegon.com/career/) - Global - [Contact](https://www.swegon.com/contact/) ## Choose a market [Or visit our global site](https://www.swegon.com) - 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According to WHO “poorly ventilated buildings affect air quality and can contribute to the spread of disease”. Other studies show that increasing the outdoor ventilation rate and minimising recirculation has a significant effect on reducing the spread of disease. With this in mind, what is the three most important actions to take, in order to optimise air handling unit operation? **1.** **Follow maintenance instructions** It is important that the ventilation unit is correctly set-up and well maintained and that the proper service routines are followed. Service personnel should follow the hygiene recommendations given by the authorities. Wearing protective clothing and washing hands after the work is completed is recommended. **2.** **Maintain a high ventilation rate** If not already running 24/7, we recommend that the ventilation is run for longer periods so that the building is well ventilated both before and after occupation. **3.** **Minimise internal leakage** To obtain the best indoor air quality we recommend that return air is minimised. Some important measures are required to minimise air leakage in units with rotary heat exchangers. To prevent the rotor from transporting air from the extract to the supply it is important that a purging sector is fitted. The function of the purging sector requires that the pressure difference is correct which means, firstly, the fans need to be correctly positioned so that they are both downstream of the rotor in their respective airstreams and, secondly, that the extract air is correctly throttled to create the correct pressure difference between extract and supply in accordance with our installation instructions. This may seem complicated, but it is good to know that in any Swegon air handling unit with rotary heat exchangers from the GOLD, SILVER C and COMPACT families, this is already taken care of. These units are all designed with the fans in the correct position and are fitted with purging sectors as standard. The rotor is well sealed both on the perimeter and across the diameter where the supply and extract airstreams are separated. Pressure measurement nipples are provided to make it easy to check the pressure balance and a pressure reducing perforated plate is included in the unit. This means that the leakage rate is less than 1% for both units with rotary and plate heat exchangers. The GOLD unit control system also features a special control function that we call Carry Over Control, that controls the rotational speed of the rotor when the airflow rate is reduced in variable air volume systems. This ensures the function of the purging throughout the operating range and reduced leakage even further. The function is easily activated via the GOLD control pad. The video clip below explains how this function can help safeguard a clean air supply into the building.               **To summarise the advice, we recommend:** - Service the units in accordance with the instructions and follow good hygienic practices - Maintain good flow rates of outdoor ventilation with a minimum of return air - Ensure that units are correctly set to avoid any unintentional return air risk These are the actions that we think are most important to focus on in the short term. In the longer term, it is of course also important that the entire HVAC industry work together to increase knowledge on healthy indoor climate and share best practises. Swegon is an active part of industry organisations such as Eurovent to publish recommendations on internal leakage and work is continuing to get it fully addressed in Certification and EN Standards. Topics: - [Air Handling Units](https://blog.swegon.com/en/tag/air-handling-units) - - - [![William Lawrance](https://blog.swegon.com/hs-fs/hubfs/William2.jpg?width=200&name=William2.jpg)](https://blog.swegon.com/en/author/william-lawrance) [William Lawrance](https://blog.swegon.com/en/author/william-lawrance) With more than 40 years of experience in the industry, William Lawrance is a Senior Product Manager at Swegon. William is also the Convenor for the CEN workgroup, responsible for preparing the AHU standards EN 13053 and EN 1886, as well as the Chairman of Eurovent Certification Compliance Committee for AHU. ## Recommended reading - [Air Handling Units](https://blog.swegon.com/en/tag/air-handling-units) ### [Anders Jakobsson](https://blog.swegon.com/en/author/anders-jakobsson) ## [Why the casing of air handling units is critical for a healthy indoor climate](https://blog.swegon.com/en/why-the-casing-of-air-handling-units-is-critical-for-a-healthy-indoor-climate?hsLang=en) To achieve a good indoor climate with low operating cost the … - [Air Handling Units](https://blog.swegon.com/en/tag/air-handling-units) ### [William Lawrance](https://blog.swegon.com/en/author/william-lawrance) ## [What is ATEX and what should be considered for hazardous environments?](https://blog.swegon.com/en/what-is-atex-and-what-should-be-considered-for-hazardous-environments?hsLang=en) In many industrial environments, safety is not simply about … - [Air Handling Units](https://blog.swegon.com/en/tag/air-handling-units) - [Acoustics](https://blog.swegon.com/en/tag/acoustics) ### [Martin Ottersten](https://blog.swegon.com/en/author/martin-ottersten) ## [Why you should eliminate all monotonous noise in your building](https://blog.swegon.com/en/why-you-should-eliminate-all-monotonous-noise?hsLang=en) Sound can be a source of pleasure and well-being, if it is the right … Get updates from the blog directly to your inbox. #### Get to know us - [Why Swegon?](https://www.swegon.com/why-swegon/) - [Solutions & services](https://www.swegon.com/solutions-and-services/) - [Products](https://www.swegon.com/products/) - [References & Insights](https://www.swegon.com/references-and-insights/) - [Support & Software](https://www.swegon.com/support/) - [Sustainability](https://www.swegon.com/sustainability/) #### More Swegon - [About us](https://www.swegon.com/about-swegon/) - [Our Brands](https://www.swegon.com/about-swegon/our-brands/) - [News](https://blog.swegon.com/en/news?hsLang=en) - [For suppliers](https://www.swegon.com/for-suppliers/) - [The Swegon Blog](https://blog.swegon.com/en) - [Swegon Air Academy](https://www.swegonairacademy.com/en/) #### Subscribe to The Swegon Blog [![](https://www.swegon.com/siteassets/logos/logo.svg?v=1620107735)](https://www.swegon.com/) Swegon Group AB, JA Wettergrens gata 7, SE-421 30 Västra Frölunda, Tel +46 (0)31-89 58 00, Fax +46 (0)31-89 94 69, info@swegon.com - [Privacy statement](https://www.swegon.com/privacy-policy/) - [Cookies](https://www.swegon.com/cookies/) - [Processing personal data](https://www.swegon.com/privacy-policy/processing-personal-data/) - [![Youtube](https://www.swegon.com/Static/img/youtube.svg)](https://www.youtube.com/user/SwegonAB) - [![Linkedin](https://www.swegon.com/Static/img/linkedin.svg)](https://www.linkedin.com/company/swegon-ab/) - [![Facebook](https://www.swegon.com/Static/img/facebook.svg)](https://www.facebook.com/swegongroup)