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VAV diffuser for office
VAV diffuser for office

Halton Jaz Conical VAV (JDS) – Conical diffuser

Variable air volume active supply diffuser for Halton Vario system. Suitable for demanding office conditions.

  • Stable throw length with variable air flow rates for enabling draught free air distribution.
  • Designed for systems with constant static pressure ductwork system


  • Stable throw length with variable air flow rates for enabling draught free air distribution
  • Installation for suspended ceiling
  • Designed for systems with constant static pressure ductwork system
  • Integrated balancing plenum with measurement and adjustment functions
  • Effective sound attenuation

Quick selection


NS Ø D H1 H2
125 124 276 114
160 159 276 114
200 199 326 139
250 249 326 139


 Part  Material  Finishing  Note
Diffuser plate  Steel Powder painted,
(RAL 9003)
 Special colours available
Front panel  Steel Powder painted,
(RAL 9003)
 Special colours available
Control cone  Steel Powder painted,
Gasket  Rubber compound
Plenum casing  Galvanised steel
Control box  Galvanised steel
 Polyester fiber
Spigot with gasket  Galvanised steel  Gasket of rubber compound
 Measurement and
adjustment module
galvanised steel
galvanised steel
Plastic parts:
polypropylene (PP)
stainless steel


The Halton Jaz Conical VAV is an active ceiling diffuser for supply air in variable conditions.

Air is supplied horizontally to the room space mainly through the slots of the diffuser.

The room air will circulate through the perforation in the front panel to the sensors located inside the diffuser.

The unit maintains a nearly constant outlet air velocity between the minimum and maximum airflow rates, create comfortable conditions and low residual air velocities in the occupied zone. Room conditions can be guaranteed without a risk of draughts, at both the maximum and minimum airflow rate.

Recommended maximum air temperature difference between supply and room air is 12 ° C.

An external room controller varies the room air flow rate by running the Halton Jaz Conical VAV diffuser actuator with a standard 0…10 VDC control signal.

The pressure dependent function of the Halton Jaz Conical VAV operates in combination with a constant pressure duct zone.

Exhaust diffuser do not include any airflow control function, will need a separate flow control damper (like Halton HFB).


The Halton Jaz Integrated VAV active diffuser shall have a minimum safety distance of 3 x duct dimension to ensure reliable measurement and accurate control of the airflow rate.

Hang the diffuser by using the brackets located on two sides of the plenum.

Alternatively ceiling integrations


               Clip-in ceilings                                      Fineline-15 ceilings         

125 124 276 114
160 159 276 114
200 199 326 139
250 249 326 139


The Halton Vario Jaz controller is a room controller dedicated to complete room applications providing the demand controlled ventilation.

  • Halton Vario Jaz diffuser integrated with room controller
  • Room air temperature measurement to control space temperature
  • Occupancy sensor for demand based operation located outside of the diffuser (separate ceiling installation)
  • Air quality control with carbon dioxide sensor, CO2

The Halton Vario Jaz room controller provides a wide variety of connections for sensors and actuators and the possibility to connect a wall mounted panel with or without a display for local set points adjustment e.g. temperature, and a wireless remote control.

See documents from the Documents-section for more information.


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

Control signals in junction box:
Terminal 1              Power supply 24 VAV
Terminal 2              Ground
Terminal 3              0 VDC   = minimum position / airflow
10 VDC = maximum position / airflow
Terminal 4               Not connected (feedback form actuator)


Make sure that the control plate of diffuser is fully open (at the lowest position). This can be done either mechanically or electrically:

  • If the power is not connected to active diffuser, detach the control plate for releasing the actuator clutch and pull the control plate 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 set point to be higher or adjust the MSM adjustment unit.

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


The maximum airflow rate of the active diffuser is measured and adjusted using the MSM module.

Airflow rate is calculated using the pressure difference reading and the k factor.

qv       Calculated airflow rate (l/s)
        Factor from the table
Δpm    Measured pressure (Pa)

The k-factors for installation with different safety distances
(D = duct diameter).

 NS > 8 * D min 3 * D
125 9,5 12,6
160 18,0 22,2
200 28,6 32,9
250 44,6 46,0

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

The minimum airflow for the diffuser is fixed by factory and cannot be adjusted.


For servicing open the front panel of the diffuser and detach the flow control element.

Detach the flow control plate by opening the screw (1) and remove the plate (2).
Remove the motor assembly (3) on JDS body by pushing the mounting shaft and let it hang on the wire.

The MSM is removed through diffuser outlet by pulling from it’s body – not from the measurement tubes or control spindle.

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

Replace all parts in opposite order. Ensure that the actuator is locked and the control plate is in right position.


The Halton Jaz Conical VAV supply air diffuser is made of painted steel with a white (RAL 9003) standard colour.
Air is introduced into the space through the adjustable control plate and the side slots of front panel, ensuring a high mixing rate. The diffuser maintains appropriate discharge velocity throughout the total airflow range.

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

The diffuser has a gasket of rubber compound to ensure tight connection to the duct work.

The diffuser enables to be equipped with sensors and control system.

Order code


S = Model
S        Supply
E        Exhaust

D = Duct connection
125, 160, 200, 250

Other options and accessories

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

IO  = Ceiling type installation options
NA      Standard T-profile
DC      Clip-In ceiling
FL        Fineline-15

RC = Room controller
NA     Not assigned
LA1    LON, HVL-527 for single unit
LA2    LON, HVL-527 for up to 6 units
LA3    LON, without room controller
BA1    BACnet, HVB-527 for single unit
BA2    BACnet, HVB-527 for up to 6 units
BA3    BACnet, without room controller

All room controller models include unit integrated temperature sensor.

SE = Sensors
NA      Not assigned
SA1    Occupancy (only with LA- and BA- series)
SA2    Occupancy and CO2 (only with LA- and BA- series)
SA3    CO2 (only with LA- and BA- series)

ED = Exhaust air diffuser control
Y        Yes
N        No

CP = Control panel
NA      Not assigned
PA2    With setpoint shift and display (BACnet and LON only)
PA3    Remote control unit (BACnet and LON only)

ZT  = Tailored product
N        No
Y        Yes (ETO)

Code example

         JDS/S-200, CO=SW, IO=NA, RC=LA1, SE=SA3, ED=N, CP=PA2, ZT=N


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