In their most simple configuration, stale air is actively drawn in by a fan and discharged to the outside. The air diffusers of such systems are usually located in extract air areas. These include the kitchen, bathroom and WC, which have more moisture and unpleasant odours compared to living spaces such as living rooms or studies. Fresh air, on the other hand, only enters the house passively through air diffusers in the building envelope, window gaps and door slits.
Central ventilation system: function, planning & installation
Topics at a glance
Many modern building projects are already equipped with mechanical ventilation systems. On the one hand, this requires a high level of energy insulation in order to regulate indoor air humidity as effectively and safely as possible. On the other hand, it is considered a comfort feature adding value to a property.
Viessmann central ventilation systems are extremely energy efficient. A powerful heat exchanger recovers up to 98 percent of the latent heat in the extract air and uses it to heat incoming fresh air. This reduces household expenditure perceptibly thanks to a significantly lower energy demand. In addition, CO₂ emissions are reduced, which means that the use of central mechanical ventilation also reduces the burden on the environment. Further features of central ventilation are explained in the section Benefits of mechanical ventilation.
How central ventilation systems work
The characteristic difference between a central and a decentralised ventilation system lies in its design. Central ventilation systems have a central ventilation unit that directs fresh air to the rooms via an air distribution system. Decentralised ventilation units, on the other hand, are installed entirely within a wall. From there, they supply the building with the required volume of fresh air.
Depending on the type of construction, central ventilation systems operate in different ways
Central ventilation can be divided into three groups:
- Simple extract air systems
- Combined extract and supply air systems
- Systems with heat recovery

Planning a central ventilation system in older and new buildings
If homeowners want to buy a central mechanical ventilation system, they should research thoroughly in advance and clarify the requirements. The first question regarding a central mechanical ventilation system should be about one's own requirements. After all, this serves as the basis for the subsequent investment. To make thing simpler, buildings are divided into three types:
- Older buildings
- Modernised older buildings
- New buildings

Installation options for the air distribution system
The operating principle of the central mechanical ventilation also involves the installation of air ducts. There are several options to choose from for installation. The best-known methods are:
- Installation in the floor structure
- Installation in concrete
- Installation in a suspended ceiling
What central ventilation systems does Viessmann offer?
A central mechanical ventilation system in a building consists of a ventilation unit and an air distribution system. The air distribution system is concealed in the floor or integrated into the wall. Air diffusers are all that remain visible. The air exchange rate is controlled independently by the central ventilation unit.
Different ventilation systems are available
Depending on the building characteristics and personal requirements, different systems for central ventilation should be considered. Ceiling units such as the Vitovent 200-C and Vitovent 300-C are designed to have a very low installation height and can be integrated into a suspended ceiling. A wall mounted unit such as the Vitovent 300-W is somewhat larger in size and can deliver an air flow rate of 300 m³/h to 400 m³/h.
All Viessmann central ventilation units can be controlled via both the ViCare and VitoGuide apps. This requires the control system to be integrated with the respective heat generator and connectivity via a Vitoconnect box. The ventilation system and heat generator thus form a central building services unit, both visually and technically. An example of this is the Vitoair FS ventilation system which can be flexibly installed: under the ceiling, on the wall or lying on the attic.
All Viessmann central ventilation systems feature heat recovery. This means they remove heat from the extract air and then transfer it to the supply air. This increases efficiency and saves heating costs.
You can find more tips and information about this in the mechanical ventilation section on heizung.de.