The principle for a ventilation-heat recovery system with supply and extract air is simple. Harmful contaminants and moisture held in the interior air is removed via the extraction vents in the “dirty rooms”; kitchen, bath, toilets and utility rooms. Before leaving the house, the old air gives off its heat to the fresh incoming air in the heat-exchange unit.
With a balanced mechanical system, you control the amount of ventilation in the house. Not too much on windy and cold days and enough on humid and mild days. At the same time the incoming air is filtered from dust and pollen. The system allows you to determine where you want the fresh air to be introduced, in what quantities and at what temperature. The fresh new air is normally supplied through a vent in the ceiling in the “clean rooms” such as bedrooms and living rooms.
A whole house ventilation system helps to provide consistent temperatures though-out the house or apartment. The house or apartment must be reasonably well insulated and draft-proofed for the system to work to its highest potential. The used air, which has now released most of its energy content, is fed out through the exhaust duct (brown duct). This happens most commonly though either a louvered grille or combi-box on an external wall, or through a roof hood.
Ventilation units make your home into a thermos! You retain the heat in the building without the need for unnecessary new thermal energy. As a result your heating system will have a much easier job to do. The kitchen extraction fan is usually kept separate to avoid contamination of the ducts and of the main unit.