Air handler

A ventilation system is a technical means to supply residential, office and service spaces outside air or "spent" or remove from this polluted air. Depending on the application, there are systems with controlled supply air ( supply air ), controlled exhaust air ( air conditioner), or combined supply and return air systems. A ventilation system is adapted to the building technical equipment, the necessary air power is determined depending on demand.

Supply air

With air supply systems it is possible, with components such as the air

  • Heat recovery (HR ) with or without moisture transfer
  • Mixing chamber,
  • Heater / air heater (LH),
  • Reheater (NE)

To influence. When cooling or humidifying the air is a partial air conditioning.

In fulfillment of the thermodynamic heating, cooling, humidification and dehumidification is air conditioning or colloquially a full air conditioning system.

To protect people and machines against contaminants from the air ( eg pollen, insects, dust), can supply air coarse and / or fine air filter and possibly have an electrostatic filter. These parts must be regularly replaced or cleaned. In larger systems, the air filters are equipped with a pressure switch. This switch generates a message when a predetermined differential pressure due to clogging of the filter or the electrostatic filter is exceeded.

Exhaust air systems

Probably the largest application area of pure exhaust systems found in toilet exhaust systems in residential or commercial buildings. Exhaust systems for sanitary areas are governed by the building regulations introduced in DIN 18017-3. Typical exhaust systems are also of withdrawal in laboratory technology means Digestorium, parking garages, or the cooker on kitchen hoods.

In boats and ships of the wind ensures that the interiors are vented through Dorade Cowl vents or fans.

Supply and exhaust air systems

Combined supply and exhaust air systems are often equipped with a heat recovery for energy saving. Heat recovery systems are required regionally in Switzerland. The savings compared to conventional ventilation corresponds approximately to the performance of the heat exchanger and is 40-90 % of the heating energy used compared to a system without heat recovery.


Supply and exhaust systems are equipped with various air filter elements for the protection of people in the room and the ventilation system itself. In exceptional cases, the exhaust air, to minimize odors or other emissions, behandlelt with appropriate filters.

For fans with a V-belt V-belt monitoring is mandatory. The monitoring can be done via a pressure switch. It measures the difference in pressure that builds up in front of and after the fan when it is running. If this pressure differential is not established for a period of about 60 seconds, the fan is turned off.

The modern solution is the monitoring by a wind vane relay or a cosPhi Guardian. This is an electrical device that is inserted into the supply of the electric motor. If the motor runs without load, ie the belt is broken, the motor is switched off.

In general, ventilation systems are equipped with automatic vent valves ( in Switzerland on the SIA Standard 180, which requires a dense buildings) that when the ventilation system is turned OFF, close. Depending on the structural fire protection on site and fire dampers between individual fire compartments are installed.

Smaller simpler ventilation systems are controlled by compact controller. For larger systems, the control is made by DDC GA controls. These are then integrated into the building automation and controlled by the building management system ( building ).

In systems with external air admixture and air / water heat exchanger to protect the heating coil frost protection thermostat is provided when the heater is operated without glycol. This disables the ventilation system when the preset temperature (variable, usually 5 ° C) below the coil. In addition, the heating valve is opened for the protection of the heating surface at 100%, the ventilation system switched off and the pump switched on. Also, any existing outside air dampers are closed, so that cool air can flow more. Furthermore, a water-side frost protection is provided often by the regulation, the return temperature is controlled by the heating valve to a minimum temperature. So that a response of the air-side frost protection thermostat is prevented.

Hygiene in ventilation systems

All ventilation systems are subject to certain hygienic requirements. In Germany this VDI 6022 was created; it regulates the responsibility of the planner, the installer, to the operator. Preventive measures or later recurring inspections, maintenance and cleaning, the ventilation system is to control and maintain their function. Sequelae that occur in connection with the building itself, the people and the ventilation system is to be summarized under the term SBS and must be eliminated.


In Germany shall be obligatory DIN and DIN EN in Europe for ventilation systems


DIN 1946 [ 2009-05 ] Air Conditioning Engineering

  • Part 4: Air conditioning systems in buildings and rooms of health care
  • Part 6: residential ventilation - General requirements, requirements for the design, execution and labeling, delivery / acceptance (certification ) and maintenance

DIN 4719 [ 2009-07 ] residential ventilation - Requirements, performance testing and labeling of ventilation units

DIN 18017 [ 2009-09 ] Ventilation of bathrooms and toilet rooms without outside windows

  • Part 3: ventilation with fans


DIN EN 12097 [ 2006-11 ] Ventilation for buildings - Ductwork - Requirements for ductwork components to facilitate maintenance of ductwork systems

DIN EN 13779 [ 2007-09 ] Ventilation for non -residential buildings - Performance requirements for ventilation and air conditioning and space cooling systems

DIN EN 15780 [ 2012-01 ] Ventilation for buildings - Ductwork - Cleanliness of ventilation systems