Smart climate control - Active Wall diffuser | Lindinvent


Equipment in a standard cell-office to control ventilation, cooling, heating and lighting via the active diffuser VTD.

The wall-mounted active supply air diffuser VTD is used when the ceiling height is not sufficient for a ceiling mounted device. VTD contains the same functionality as the roof-mounted active diffuser TTC.

Built-in sensors
VTD has built-in sensors for pressure, air flow, duct temperature, room temperature and presence.

Inferior air mixing capability and risk of draft
A wall-mounted diffuser provides less air mixing than a ceiling-mounted diffuser. A wall mounted diffuser can cause draft problems. See our CFD runs.

Adjustable grid
The adjustable grid can be used in order to direct the air towards any surface.

A Cell-office with the wall-mounted active supply air diffuser VTD. VTD offers a solution where the climate in the individual room can be adapted using the variable supply air flow and the device's built-in logic to control connected valve actuators.

The amount of air is regulated by actively raising or lowering the height between the lamellas in the diffuser section. The pressure and flow sensor together with the encoder on the damper motor ensures accurate flow control. The level of the air flow is regulated to meet the room temperature setpoint. The resulting air flow is somewhere between preselected and calibrated flow points. Levels are set after an absence, presence and maximum air flow. The built-in presence detector is used for activating the economy mode (the absence level of the flow is activated) or the comfort mode (the presence level is activated) after an adjustable time delay.

Extract air via transfer air to a corridor
Extract air balancing takes place via transfer air to the corridor. Extract air devices are located in the adjacent corridor where the smart damper DCV-BL balances the summed supply air flow from several rooms. Supply air flows and extract air flows are communicated digitally via the CAN bus.

Heating or cooling
A set of adjustable P-bands is used by VTD to regulate the office's climate in a way that avoids parallel heating and cooling. VTD activates the actuators for heat when the supply air cannot keep the climate in accordance with set points. There is no extra cooling system installed here. A cold draught protection function can be implemented.

Signals from built-in sensors are used by VTD to regulate the room climate according to setpoints.

VTD can flexibly control the office lighting via the presence sensor or via signals from other control units. Time for ignition from detected presence (an operating mode) can be set, as well as the time for switching off the lighting after the last registered presence. If a more advanced lighting solution is desired, with scenes etc., lighting control SBD can be used for a DALI solution.


The cable in use for linking units to a communication loop (CAN bus) is a PVC-free shielded 4-conductor combined supply and communication cable. Relay boxes and sensors etc are normally connected via connection box CBX using the same cable specification. The 4-conductors are used for power supply and signals when applicable.

Cable lengths
The CAN bus cable can be pulled long distances with respect to communication, but, for power supply to be at acceptable levels, voltage drop must be considered. See the electrical design guide.

Power supply and transformers
In a normal situation, one 230/24VAC transformer is installed per 12 to 15 diffusers/nodes on the CAN-bus section. This is a rule of thumb that applies at short distances between products. See the electricity design guide for details.

It is not optimal to supply cold air from a wall mounted diffuser. As the report shows, cold air is pressed down towards the floor. To resolve this situation, it is recommended to direct the grille towards a wall without a desk in order to create a rotation of air in the room. This procedure works in smaller rooms but not at all in open plan offices or conference rooms. In this case we advise you to use PBF/ a flat duct (see Cellular office/Low ceiling height: Ceiling diffuser).

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