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Circle displacement ventilation unit, Halton Zen Circle (ZCI).
Circle displacement ventilation unit, Halton Zen Circle (ZCI).

Halton Zen Circle (ZCI) – Displacement ventilation unit

This circular displacement ventilation unit is an excellent choice for middle space positioning.

  • Capacity for wide supply airflow range.
  • Low velocity air is diffused at the floor level, making the unit suitable for positioning in the centre of a space.


  • Capable of alarge supply airflow range
  • Uniform supply air distribution is achieved through small perforations, providing optimal conditions in the immediate proximity of the diffuser.
  • Low velocity air is diffused at the floor level, making the unit suitable for positioning in the centre of a space.
  • The air flow is patterned for 360 degrees of diffusion, enabling large airflow rates with low residual velocities in the occupied zone.
  • The detachable front plate enables cleaning of the unit and ductwork
  • Circular duct connection with an integrated rubber gasket on the top/bottom.

Product models and accessories

  • Model with stainless steel (AISI 316L) design
  • Model with thick front panel (1.5 mm)
  • Air flow equalization plate when ducted from bottom
  • Duct cover
  • Installation base (standard or high store model)

Quick selection

Dimensions and weight

   NS   ØW  H  ØD
  125  320   600  124
  160  360   600  159
  200  360  1000  199
  250  410  1200  249
  315  475  1600  314
  400  560  1600  399
  500  660  2000  499
  630  790  2000  629
  •  AB/ZCI installation base: height = 100 mm
  •  SB/ZCI installation base, high (store) model:
    Height = 200 mm, W=W+120


NS kg
125 11.3
160 13.3
200 18.2
250 25.4
315 38.0
400 45.9
500 66,4
630 82,7


Part Material Note
Front panel Perforated galvanised steel Stainless steel (AISI 316L)
as option
Casing Galvanised steel Stainless steel (AISI 316L)
as option
Flow equalisation
Plastic net
Pressure measurement pipe Plastic
Spigot Galvanised steel
Gasket Rubber compound
Optinonal top cover Plastic
Installation base Galvanised steel
Finishing Polyester-epoxy-painted
White (RAL 9003/30% gloss)
Special colours available


Accessory Code Description  Note
Duct cover (1) DC Standard lengths
500/1000/1500/2000 mm
Installation base (2) AB Standard height 100 mm
Installation base SB Standard height 200 mm/
Dimensions = unit size + 60 mm
High (store) model

Product models

  • Model with stainless steel (AISI 316L)
  • Duct cover (DC) made of perforated steel (same as ZCI-unit)
  • Thick front panel (1.5 mm)
  • Airflow equalization plate when ducted from bottom


Air is supplied into the space uniformly through the front panel of the unit,  generally at a slightly lower temperature than the room air. The supply air flows down to the floor level, before gradually pervading the occupied  zone at a low velocity. Finally the convection of warm surfaces causes the air to rise out of the occupied zone. The low velocity flow pattern is circular (360°). The low velocity flow pattern is directed forward.

The non-clogging unit can be easily opened and cleaned.

Halton PRA or Halton PTS/C can be used as an airflow adjustment damper in duct. The safety distance for reliable airflow measurement from the displacement unit is 5 duct dimensions between displacement unit and airflow adjustment damper.
If airflow adjustment damper is installed closer to the displacement unit (minimum distance about 3 duct dimensions), supply air throw pattern is correct, but air flow measurement result will not be accurate.
When installing airflow adjustment damper close to the displacement unit (minimum 3xD), attenuator could be needed between the damper and the displacement unit.

 Note: The flow pattern data has been defined for floor installation.


Perform the installation in the following order:

A)  Without AS/AB base:
Open diffuser and fix onto floor with screws (not included in delivery)

With AS/AB base:
Fix 3 mounting brackets (2) on to floor and then fix AC/AB base cover (1)
onto these.

B)  After installation of ductwork (7)  position the DC duct cover as follows:
Position the fixed half of the DC (5) so that joint of the unit and DC
are in same position.  Install brackets (6) into DC
Position and fix the other opening half of the duct cover (4)


The supply flow rate is determined by measuring the differential pressure from the measurement nipple with a manometer. Use a measurement probe thin enough fit into the nipple. Then use tape or another gasket to create a seal in the nipple in order to get an accurate reading.

The flow rate is calculated using the formula below:

The values for k factor for formula
(D = duct diameter)

D k
125 12.0
160 21.1
200 31.9
250 51.3
315 78.9
400 119.7
500 182.6
630 257.8


Code description
1.   Front panel
2.   Detachable service plate
3.   Casing

Open the front panel (1) by carefully pulling the spring connections out. Unscrew the service plate (2) screws and remove the plate. If required, the flow equalization nets can be detached.

Wipe the parts with a damp cloth. Do not immerse in water.

Reassemble after cleaning in reverse order.


The Halton Zen Circle displacement ventilation supply unit is made of galvanised steel, polyester-epoxy-painted with a white (RAL 9003) colour.

The unit has a robust maintenance free, non-clogging design.

The unit is comprised of a detachable, perforated front panel, removable service plate,
a plastic internal fixed flow equalisation element, and casing.

The unit has a circular duct connection at the top or bottom depending on the location of the unit.

Mounting brackets are included in the delivery, srcews not.


The unit can be equipped with a duct cover and/or installation base, where required.

Additionally, different colours and surface patterns are available on separate request.

The front panel of the unit is available of 1.5mm thick galvanised steel for demanding spaces.

Order code


D = Diameter of duct connection (mm)
125, 160, 200, 250, 315, 400, 500, 630

Other options and accessories

MA = Material
CS     Steel
AS     Stainless steel (AISI 316L)

TP = Front panel thickness 1.5 mm
N        No
Y        Yes

CO = Colour (metallic parts)
SW   Signal white (RAL 9003)
X      Special colour

TM = Top cover (in the opposite end of duct connection)
F      Flat (standard)

BM = Installation
T       Ducting from top
B       Ducting from bottom

ZT  = Tailored product
N       No
Y       Yes (ETO)

Sub products

DC    Duct cover
AB    Standard base
SB    High store base

Code example

ZCI-200, MA=CS, TP=N, CO=SW, TM=F, BM=0, ZT=N


Halton Zen Circle (ZCI) – Displacement ventilation unit
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