Heat recovery ventilation: choosing and maintaining your system

# Heat recovery ventilation: choosing and maintaining your system Before choosing a mechanical ventilation system with heat recovery, have the duct routes, noise and maintenance access assessed. For an existing installation, start with the correct manual and documented settings. The unit's model is not enough to assess the whole installation, nor does it guarantee savings or additional value when selling. ## How does air circulate through the house? In a system D, supply and extraction are mechanical. With heat recovery, outgoing air preheats incoming air. The [SPW WALLORENO 2026 guide, pages 27 and 28, in French](https://energie.wallonie.be/files/PEB/B%C3%A2timents%20r%C3%A9sidentiels/R%C3%A9novation/Outils/Publications/Walloreno/brochureWalloreno_2026.pdf#page=27) describes supply into dry rooms, transfer towards wet rooms and extraction. This guide highlights the more complex installation of heat recovery ventilation and places it within a major renovation. It states that a system C is often easier to install in an existing home. Compare the options with the designer before choosing the unit. ## What should you have clarified in the quotation? For a character home in the Province of Liège, our method is to request a diagram specific to the building and a detailed quotation. In particular, have the following clarified: - duct routes, lowered ceilings and finishes; - access to the unit, filters and parts of the network requiring maintenance; - noise control near bedrooms and the space available to work; - the price of design, equipment, installation, alterations and maintenance. The unit may fit in the loft without the duct routes being resolved. Without an assessment of the house, a general budget does not provide a basis for comparing the options properly. Also ask for the cost and reference of compatible filters rather than choosing on the price of the unit alone. ## What should you request at commissioning and for maintenance? Performance depends on sizing and adjustment. [Buildwise's Optivent tools, described in French](https://www.buildwise.be/fr/expertise-soutien/buildwise-tools/optivent-syst%C3%A8mes-de-ventilation/) support tasks including adjusting airflow rates on site and preparing a report. Ask for an explanation of the controls, everyday operating modes and alerts, along with documented settings, ideally in a report. This is practical advice, not a claim that the same report is compulsory for every installation. For an existing installation, follow the maintenance and safety instructions in the correct manual. Do not adopt the frequency given for another unit. Before altering a vent with an unknown setting, ask for it to be checked. If there is an unusual noise or persistent alert, contact the professional and ask about the diagnostic cost before the visit. ## Which documents should you keep before selling? Gather the manual, unit and filter references, available plans, documented settings and intervention records. Identify any missing documents. Present only verifiable features, without inferring compliance from the words 'heat recovery ventilation' alone. Our guide to [renovating or selling as is](https://youhome.immo/en/journal/renovate-or-sell-as-is/) helps place the expense within your property project. The technical study remains the responsibility of the appropriate professional. ## What are the answers to frequently asked questions? ### Should you install heat recovery ventilation before selling? Not automatically. Compare feasibility, the complete quotation and your sale timetable. Adding this equipment alone does not guarantee a higher price. ### Is there a maintenance frequency that applies to every unit? Do not adopt the instructions for another model. Start with the correct manual and ask which operations require a professional. ### Does an installation invoice prove the current settings? Do not read more into it than it actually contains. Look for documented settings and subsequent interventions; have unknown points assessed rather than presenting them as verified. To place the works within your sale project, you can [request your valuation report](https://youhome.immo/en/valuation/request/). It does not replace a ventilation assessment.