The Kombivent series of air handling units is ideally suited for ventilation systems.

These are a supply unit comprising a damper, filter, heater and fan and an extract unit consisting of a fan or fan and damper. When the air handling unit is inoperative the damper should be closed in order to protect the heating coil from frost and to prevent back draught through the system. Additional protection of the coil may be provided by the installation of an electric heater element within the unit.

The heating capacity should be sufficient to warm the incoming air to the desired temperature during the heating season. The supply fan draws in fresh air from the outside and distributes it through the ducting system; the extract fan removes the stale air from the ventilated area and discharges it from the outside.

Units may also be provided with an air mixing section so as to enable re-circulation or partial re-circulation of the air, if required.

This ventilation system can be extended by the addition of a section for cooling and/or dehumidification of the air. For this purpose, a chilled water cooling coil, led from a remote water chiller, is included in the unit. Alternatively a direct expansion cooling coil may be used, whereby the coolant, circulated by a remote compressor and condensing unit, evaporates within the coil.

In combined systems, the supply ventilation unit and the extract fan are combined to form one air handling unit, by inserting a combined damper mixing section. This section not only enables air to be discharged but also to be re-circulated to supplement the outside air as required and reduce the heating load. The ratio of the two air quantities is adjustable.

To obtain complete air handling, the air handling unit can be extended to include humidification. Humidification can be affected by a diabatic humidification of the air by means of a water sprinkling device or a package humidifier. Humidification can also be provided by injecting steam into the air. With adiabatic humidification, the air should be pre-heated to enable it to absorb sufficient moisture, and to achieve satisfactory control should, in many cases, be re-heated because air cools down as a result of this humidification process.

The level of humidity can be regulated by switching the pump on or off, by adjustment of the water supply by means of a three-way valve, a multi-speed or adjustable speed pump motor. In case of steam humidifying, re-heating is not necessary because the required latent heat is already available in the steam.

• Rotorvent - Rotating heat wheel


• Twinvent - Twin coil system (Run-a-round)


• Direktvent - Plate type heat exchanger


• Heatvent - Heat-pipe exchanger

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