COAXIAL Stainless Steel Concentric Chimney Systems

The COAXIAL range is a concentric stainless steel flue system designed to manage both combustion-air intake and flue-gas exhaust through one combined system.

The construction consists of an AISI 316L BA stainless steel inner flue for combustion products and an AISI 304 BA stainless steel outer wall. In compatible configurations, the annular space between the two ducts is used to supply combustion air to the appliance.

The system is particularly suitable for appliances designed for concentric operation, including sealed pellet stoves, gas appliances, wood-burning appliances and other compatible heat generators, according to the applicable system designation.

How does a concentric flue system work?

A concentric system manages two separate flows within the same assembly:

• the inner duct carries combustion products towards the exterior;
• the annular space can supply combustion air to the appliance.

For appliances designed for this configuration, this can avoid the need for a completely separate combustion-air duct.

COAXIAL technical specifications

T200 and T600 configurations

COAXIAL can be configured according to the operating conditions of the installation.

With the specified sealing gasket, the stated designation is T200 – P1 – W – V2, suitable for the system applications requiring positive-pressure and wet operation.

For high-temperature configurations, the stated designation is T600 – N1 – W – V2.

The correct configuration must be selected according to the connected appliance, fuel, flue-gas temperature, operating pressure and appliance manufacturer's requirements.

Main applications

The system is designed for modular flue applications serving different heat generators, including:

• pellet stoves;
• wood-burning stoves;
• fireplaces;
• gas appliances;
• traditional and condensing heat generators;
• atmospheric and pressurised appliances;
• other applications compatible with the relevant system designation.

The appliance must be specifically suitable for concentric flue operation and compatible with the required diameters and system performance.

Suitable for sealed appliances

Concentric systems are particularly useful with sealed appliances designed to draw combustion air directly from outside.

In these installations, both the combustion-air supply and flue-gas exhaust can follow the same route while remaining separated inside the concentric system.

Available concentric sizes

• Ø80 / 130 mm;
• Ø100 / 150 mm;
• Ø130 / 200 mm;
• Ø150 / 200 mm;
• Ø180 / 230 mm;
• Ø200 / 250 mm.

Available dimensions may vary according to the individual component.

Available COAXIAL components

• straight pipes in different lengths;
• telescopic sections;
• 30°, 45° and 90° elbows;
• 90° T-connectors;
• reducers and adapters;
• probe modules;
• support plates and brackets;
• terminals;
• fixing and finishing accessories;
• connection kits for sealed stoves.

Concentric and insulated twin-wall systems are different

A concentric flue system should not be confused with a conventional insulated twin-wall chimney.

In the COAXIAL system, the space between the two ducts is used as part of the combustion-air circuit. In an insulated twin-wall chimney, the space between the walls is normally used for thermal insulation.

The correct system therefore depends on the appliance configuration and chimney design.

How to select COAXIAL components

Before purchasing, check:

• that the appliance is compatible with a concentric flue system;
• the flue outlet diameter;
• the required combustion-air diameter;
• the required inner/outer diameter combination;
• flue-gas temperature;
• operating pressure;
• possible condensate formation;
• overall flue route length;
• number and angle of elbows;
• compatibility between all system components.

The system must be configured according to the appliance manufacturer's instructions and the relevant flue-system technical documentation.

Browse the COAXIAL straight pipes, elbows, fittings, terminals and connection kits below to select the components required for your installation.