Suction cup
The flue gas venturi represents the simplest and most economical exhaust system for gas boilers and combustion air heaters. At Climatik, we support French professionals in selecting venturis suitable for gas heating installations requiring horizontal wall exhaust without a vertical flue.
Our range includes 60/100 mm and 80/125 mm concentric venturis, complete kits with ducts, elbows, and wall terminals. These systems allow for flue gas exhaust and combustion air intake through a simple wall penetration, without a chimney.
Principle of the concentric venturi
Sealed circuit operation
The concentric venturi uses a double-pipe system: the inner pipe exhausts combustion gases to the outside, while the outer pipe draws in fresh air for combustion from the outside. This sealed circuit configuration does not draw any air from the heated room, ensuring optimal safety and maximum efficiency.
Major advantages: horizontal wall installation simply passing through the facade (single Ø 100-130 mm hole), no costly vertical duct, no mandatory sweeping, maximum length 5 to 10 meters depending on models with the possibility of 2 90° elbows.
Standard diameters
60/100 mm venturi: Inner flue pipe Ø 60 mm, outer air pipe Ø 100 mm. Suitable for gas boilers and air heaters up to 35 kW. Applications: small tertiary premises, domestic boiler rooms, small workshops. Investment: €150 to €400 for a complete kit.
80/125 mm venturi: Inner flue pipe Ø 80 mm, outer air pipe Ø 125 mm. Suitable for installations from 35 to 100 kW. Applications: industrial workshops, warehouses, collective boiler rooms, medium-power gas air heaters. Investment: €250 to €700 for a complete kit.
Installation configurations
Horizontal through-wall venturi
The horizontal venturi passes through the wall perpendicularly with a slight downward slope towards the outside (3-5%) for condensate drainage. Maximum horizontal length: 3-5 meters in a straight line without an elbow. Anti-backflow outdoor terminal with weather protection grille. The most common and economical configuration.
Venturi with elbows
90° or 45° elbows allow for bypassing obstacles (beam, structure) between the appliance and the exterior wall. A maximum of 2 90° elbows are allowed, with each elbow reducing the total permissible length by 0.5 to 1 meter. Use specific venturi elbows with high-temperature gaskets provided.
Vertical venturi
The vertical venturi exhausts to the roof when the exterior wall is inaccessible or too far away. Maximum vertical length: 8-10 meters. Requires a waterproof roof terminal with a rain cap. More expensive than horizontal installation but avoids traditional chimney work.
Installation and compliance
Regulatory safety distances
The external venturi terminal must comply with minimum distances: Window or door opening >60 cm. VMC ventilation outlet >60 cm. Ground, balcony, accessible terrace >3 meters (descending fumes). Neighboring property >60 cm. Re-entrant facade angle >30 cm.
Professional implementation
Installation requires: wall drilling with appropriate diameter (Ø 110 mm for 60/100, Ø 135 mm for 80/125), waterproof wall penetration sleeve, downward slope of 3-5%, venturi sealing on the appliance, sealed connection with supplied gaskets, outdoor terminal fixed with safety distance. Duration: 2-4 hours per installation.
Checks and maintenance
Annual mandatory check with boiler/air heater maintenance: verification of connection tightness, absence of obstruction (bird nests, leaves), good condition of the outdoor terminal, maintained slope, drained condensates. No mandatory sweeping (sealed circuit). Gasket replacement: every 8-10 years (€20-50). Venturi lifespan: 15-20 years.
Professional applications
Industrial gas air heaters
Gas air heaters from 20 to 100 kW primarily use 80/125 mm venturis for simple wall exhaust. Avoids costly vertical chimney through the roof. Quick installation, reduced cost, easier maintenance.
Collective boiler rooms
Gas boiler rooms supplying several buildings favor venturis for boilers up to 100 kW per unit. Beyond that, a collective chimney is mandatory. Venturis allow for basement boiler room installation with horizontal facade exhaust.
Tertiary premises
Offices, shops, workshops equipped with gas wall boilers use 60/100 mm venturis for discreet facade exhaust. Preserves aesthetics, no visible duct on the roof.
Complementary uses
For installations requiring a vertical duct, consult our professional flue systems collection: double-wall insulated ducts, flexible and rigid flues, accessories compliant with DTU 24.1.
Climatik expertise
At Climatik, we advise you on choosing the venturi diameter based on appliance power, optimal configuration (horizontal or vertical), compliance with safety distances, and compatibility with your existing installation.
All our flue gas venturis are available in stock with fast delivery throughout France from our warehouse in Olivet.
