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Halton VHB – VAV diffuser

Exposed square active diffuser for variable airflows, which works in constant pressure duct system.

  • Stable throw length with variable supply airflow rates
  • Installation for suspended ceiling


  • Installation for suspended ceiling
  • Stable throw length with variable supply airflow rates
  • Wide supply air temperature range
  • Suitable for systems with constant static pressure ductwork system
  • Designed for use with the Halton TRI/V plenum
  • Maximum flow rate adjustment and measurement section available for supply (MSM)
  • Minimum airflow between10…15 l/s for sizes 160…250


160 299 234 98 159
200 449 267 104 199
250 449 275 116 249

Dimensions with Halton TRI/V plenum

160 160…160 458 299 222 96…126 432 159 162
200 200…200 618 449 272 100…130 592 199 202
250 250…250 618 449 336 111…141 592 249 252


 Part  Material  Finishing
 Upper plate  Steel  Powder painted, white (RAL 9003)
 Front panel  Perforated steel  Powder painted, white (RAL 9003)
 Control cone  Steel  Powder painted, black
 Gasket  Rubber  –



In the standard delivery the Halton VHB is always equipped with a Siemens GDB161.2E/HA damper actuator.

Actuator Force Control
GDB161.2E/HA 125 Nm 0…10 VDC 24 VAC 3VA


The Halton VHB is an active ceiling diffuser for supply air.

Air is supplied to the room space mainly through the side slots of the diffuser. The air jet supplied horizontally through the side slots induces room air.

The unit maintains a high outlet air velocity between the minimum and maximum airflow rates, creating comfortable conditions and low residual air velocities in the occupied zone.

In the demand-based ventilation (DBV) and variable air volume (VAV) systems, room conditions can be guaranteed to be without a risk of draughts, at both the maximum and minimum airflow rate.

The pressure dependent function of the Halton VHB operates in combination with a constant pressure duct zone.
An external room controller varies the room airflow rate by running the Halton VHB diffuser actuator with a standard 0…10 VDC control signal.

Halton TRI/V plenum for supply air

Use of the Halton VHB is most beneficial with a Halton TRI/V plenum.

The plenum includes:

  • A measurement and adjustment module MSM
  • An electric junction box for power and control signal supply as well as an cable for easy connection of the variable air diffuser Halton VHB
  • Installation safety and hanging wire for air diffuser


The active diffuser is installed in conjunction with the Halton TRI/V plenum box. The Halton TRI/V plenum has a safety distance of 3D minimum upstream, to ensure reliable measurement and accurate control of the airflow rate.

A hanging and safety wire for Halton VHB diffuser is delivered with the Halton TRI/V plenum. Hang the Halton VHB diffuser to the wire by means of a key ring.

Halton VHB is connected electrically to Halton TRI/V with ready assembled cable plug.

Control that the actuator settings are in line with the factory pre-setted DIL switches.

Release the actuator clutch and pull the control cone to the fully open position.

Mount the Halton VHB diffuser assembly to the Halton TRI/V plenum box.

The technical performance for the combination of supply air diffuser and plenum is presented separately for the two different installations.

Dimensions of installation hole in suspended ceiling

160 211
200 265
250 333


Wiring diagram

Junction box                                          Cable connection plug

Control signals in junction box

Terminal 3

  • 0 VDC  = minimum position/airflow
  • 10 VDC  = maximum position/airflow

Terminal 4 (feedback from actuator)

  • Not connected


Make sure that the control cone of each active Halton VHB (and VHD) damper is fully open (at the lowest position). This can be done either mechanically or electrically:

  • If the power is not connected to active diffuser, release the actuator clutch and pull the control cone to the fully open position.
  • If a 24 VAC power supply is connected to diffusers, please make sure that the control signal is constantly at 10 VDC.

Check that the duct zone constant pressure is at the intended level (for example, between 30 and 50 Pa).

If the duct zone pressure is too low and the zone pressure control damper is fully open, you should either adjust the supply fan pressure setpoint to be higher or adjust the MSM adjustment unit in the Halton TRI/V plenum.

The zone pressure control damper shall have a sufficient operative differential pressure over the damper (for example, 30 Pa or more).


The airflow rate of the active diffuser is measured and adjusted using the MSM module inside Halton TRI/V plenum.

Attach the measurement instrument to the measuring tubes on Halton TRI/V plenum and the airflow rate is calculated using the pressure difference reading and the k factor.

qv           Calculated airflow rate [l/s]
k              k factor from the table
Δpm         Measured pressure [Pa]

NS k factor
160 15.9
200 26.2
250 44.5

If the airflow rate of the active diffuser is too high, adjust the position of the MSM adjustment unit in the Halton TRI/V plenum to closer position. If maximum airflow can’t be reached, open MSM module first full open and if this is not enought, increase the duct zone pressure

The minimum airflow is factory pre-adjusted.


Open the diffuser part and detach the perforated plate of the coupling sleeve. Remove the control cone part completely.

Loosen two screws which are holding the motor assembly on Halton VHB body and let it hang on the wire.
The MSM is removed through Halton TRI/V outlet by pulling from it’s body – not the measurement tubes or control spindle.

Clean the parts with a damp cloth, instead of immersing in water.

Replace all parts in opposite order.


The active diffuser is made of painted steel with a white (RAL 9003) standard colour.
Air is  introduced into the space through the side slots and perforated front panel, ensuring a high mixing rate. The diffuser maintains appropriate discharge velocity throughout the total airflow range.

The diffuser is connected to a balancing plenum designed for the active diffuser installation and equipped with a measurement and adjustment module.

The diffuser has e a rubber gasket to ensure tight connection to the plenum.

Order code


D = Duct connection size
160, 200, 250

Other options and accessories 

CO = Colour
SW     White (RAL 9003)
X        Special colour (RAL xxxx)

ZT = Tailored product
N        No
Y        Yes (ETO)

Sub products

TRI/V  Plenum

Code example

VHB-160, CO=SW, ZT=N


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