Skip to content
Adjustable diffuser
Adjustable diffuser

Halton THL – Conical diffuser

Circular conical diffuser for ceiling installation. Ideal for high spaces and easy to clean and maintain.

  • Suitable for both heating and cooling applications
  • Adjustable throw pattern (radial or compact jet)


  • Horisontal or vertical air supply
  • Suitable for both heating and cooling applications
  • Adjustable throw pattern (radial or compact jet)
  • Installation flush to the ceiling, or exposed (especially in high spaces)
  • Circular duct connection with gasket
  • Openable front disk enables cleaning of the diffuser and ductwork


  • Plenum options with measurement and adjustment functions

Quick selection

Fig.1. Halton THL with TRH plenum.


Halton THL, manual

100 286 97 25 9 99
125 286 97 25 9 124
160 286 97 25 9 159
200 354 81 30 10 199
250 440 84 39 12 249
315 546 102 52 14 314
400 685 135 70 14 399

Halton THL with wax-bulb actuator

250 440 84 39 12 173 249
315 546 102 52 14 193 314
400 685 135 70 14 215 399


Part Material Note
Frame Steel
Front disk Steel
Finishing Painted, white
(RAL 9003)
Special colours available


Accessory Code Description
Balancing plenum TRI For balancing, equalising the airflow
and attenuating the duct noise
Balancing plenum TRH For balancing, equalising the airflow
and attenuating the duct noise
(mineral wool and polyester fibre)

Product Models

Halton THL, manually operated

Changing manually the front disk position the throw pattern can be adjusted from radial to compact.

Halton THL with wax-bulb actuator

Sizes 250, 315 and 400 can be equipped with a wax-bulb actuator, which work without any power supply. The front disk position changes according to the temperature of supply air. The temperature range of the wax-bulb actuator is about 20 °C to 27 °C.

The time taken to change from radial to compact jet (or the other way around) is 10 – 20 minutes.
When warm air is supplied the piston of the wax bulb actuator keeps moving until the THL supply air pattern is vertical. When cold air is supplied, the Halton THL supply air pattern is changed back to horizontal by means of a spring.


                  Compact jet                                              Radial jet

The Halton THL is a ceiling diffuser with an adjustable low pattern.
The horisontal radial jet is used mainly in cooling applications and the vertical compact jet with warm supply air in heating applications.

The supply air pattern can be adjusted by rotating the front disk into the desired position.
The recommended maximum temperature difference in cooling applications between supply and room air temperature is 10 °C.


Code description
1.  Front disk
2.  Frame

The diffuser is connected either directly to the duct by screwing or riveting or alternatively to the Halton TRI balancing plenum.

The minimum recommended safety distance upstream of the diffuser is 3xD.

Installation with Halton TRI

The collar of Halton TRI plenum can be installed either internally in the plenum or externally onto the bottom of the plenum.
The height of the unit for the external installation is presented in the table below.
When the collar is installed internally, the total height H3 is reduced by 60 mm.

100 100 TRI-100-100 244 9 242-282
125 100 TRI-100-125 244 9 242-282
125 160 TRI-125-125 244 9 272-312
160 125 TRI-125-160 244 9 272-312
160 160 TRI-160-160 244 9 312-352
200 160 TRI-160-200 306 10 312-352
200 200 TRI-200-200 306 10 371-411
250 200 TRI-200-250 384 11 380-420
250 250 TRI-250-250 384 11 444-484
315 250 TRI-250-315 482 13 455-495
315 315 TRI-315-315 482 13 500-550
400 315 TRI-315-400 617 14 518-558


The Halton THL itself has no means for airflow adjustment.

In order to enable airflow adjustment and measurement of airflow rate it is recommended that the diffuser be connected to the Halton  TRH or TRI balancing plenum. The supply airflow rate is determined by using the measurement and adjustment module MSM.

Detach the front disk or the whole diffuser and pass the tubes and control spindle through the side slot of the diffuser.
Replace the front disk or diffuser.
Measure the differential pressure using a manometer. The airflow rate is calculated using the formula below.

Adjust the airflow rate by rotating the control spindle until the desired setting is achieved.
Lock the damper position with a screw.
Replace the tubes and spindle into the plenum.

The k-factor for installations with different safety distances (D= duct diameter)

TRI > 8 x D min 3 x D
100 6.0 7.5
125 9.9 12.6
160 16.9 21.9
200 28.3 31.0
250 47.9 51.5
315 78.6

The technical performance has been defined for radial and compact jet with the fixed cone module openings. The adjustment positions used are detailed in the table below.

Size Radial jet Compact jet
100 8 -4
125 10 -4
160 12 0
200 15 0
250 19 0
315 24 0
400 30 0


Measure the distance between the front disk and the upper frame in order to enable recovery of the same technical properties after cleaning.

Detach the front disk of the diffuser and clean the parts by wiping with a damp cloth.
Reinstall the front panel.


The ceiling diffuser has a steel casing with an adjustable front disk and a spigot with integral gasket for connection to the circular duct.

The diffuser is polyester or painted white (RAL 9003) colour.
The throw pattern of the diffuser is adjustable in radial or compact jet.

Order code


 D = Duct connection size
 100, 125, 160, 200, 250, 315, 400

Other options and accessories

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

MO = Actuator type
NA     Not assigned
M1     Wax-bulb actuator (if D = 250, 315 or 400)

ZT = Tailored product
N       No
Y       Yes (ETO)

Sub products

TRI     Balancing plenum
TRH   Balancing plenum

Code example



Halton THL – Conical diffuser
Halton THL – Kartiohajottaja
Halton THL – Diffuseur plafonnier à cône réglable
Halton THL – Konisk takspridare
Halton THL – Deckenauslass
Halton THL - fr
629.18 KB
  • Max. file size: 128 MB.