Double Flap Smoke Ventilator 1
Double Flap Smoke Ventilator 3
Double Flap Smoke Ventilator 2
Double Flap Smoke Ventilator 6

Duo Therma

Double Flap Smoke Ventilator Solution

The Duo Therma is the solution for projects that require high acoustic or thermal performance together with low air leakage, for instance theatres, cold stores and schools. With achievable U values as low as 0.9W/m² deg K, acoustic reductions Rw of 31 dB and no air leakage at 50 Pa, it is the ultimate performance ventilator.

The Duo Therma extracts large volumes of smoke, utilizing the buoyancy of hot gases in the rising plume. Natural day-to-day ventilation is driven by pressure differences to move fresh air through the building. Pressure differences are caused by wind or the buoyancy effect created by temperature differences commonly known as the “stack effect”.

The Duo Therma is available with various flap types including insulated aluminium, glazed or polycarbonate. Operated either electrically or pneumatically with base options for fixing onto roof sheeting or upstand.


  • Zero air leakage at 50 Pa
  • Thermally broken
  • Low U value
  • 44 dB noise reduction achievable


  • Manufactured to NEN-EN-ISO9001
  • Tested and certified to BS EN 12101


  • Mill Finish
  • Polyester Powder Paint


  • Pneumatic
  • Electric


  • Length - 2000mm to 2760mm
  • Width - 1500mm to 2760mm


  • Bird Guard
  • Insect Guard


  • Onto Roof Sheet
  • Onto Upstand
Duo Therma Brochure
Call the Delta Solutions Team
+44 (0)23 9286 3888
Double Flap Smoke Ventilator 4
Double Flap Smoke Ventilator 5