ISO25 PLUS – AISI 316L G50 Insulated Twin-Wall Chimney

De Marinis ISO25 PLUS is a modular twin-wall chimney system insulated with 25 mm of mineral wool, designed for indoor and outdoor flue and chimney installations.

The main development compared with the traditional ISO25 range is its G50 classification: in the certified high-temperature configuration, ISO25 PLUS allows the chimney to be installed with a declared 50 mm clearance from combustible materials.

The inner wall is manufactured from AISI 316L BA stainless steel, while the outer wall is available in AISI 304 BA stainless steel or natural copper. The two walls are separated by 25 mm of high-density mineral wool insulation.

ISO25 PLUS: the new G50 twin-wall chimney

The key feature of the ISO25 PLUS range is its T600-N1-W-V2-L50040/050/060-G50 designation.

The G50 classification identifies soot-fire resistance with a declared 50 mm clearance from combustible materials in the certified configuration.

This makes ISO25 PLUS particularly suitable for installations close to timber roofs, floors, beams and other combustible structures, always in accordance with the manufacturer's installation instructions.

ISO25 PLUS technical specifications

T200 P1 and T600 G50 configurations

ISO25 PLUS can be configured according to the operating conditions of the chimney system.

With the manufacturer's specified sealing gasket, the designation is:

T200-P1-W-V2-L50040/050-O40

This configuration is designed for wet flue gases and positive-pressure operation up to 200 Pa.

For high-temperature applications without gasket, the designation is:

T600-N1-W-V2-L50040/050/060-G50

This configuration covers wet or dry flue gases, negative-pressure operation and temperature class T600, with soot-fire resistance and G50 clearance from combustible materials.

25 mm high-density mineral wool insulation

ISO25 PLUS uses 25 mm of high-density mineral wool insulation between the inner and outer walls.

The construction is designed without direct metallic connections between the two walls along the body of the component that could create a thermal bridge.

AISI 316L stainless steel inner wall

The wall in contact with combustion products is manufactured from AISI 316L BA stainless steel.

The declared corrosion resistance classification is V2.

Stainless steel or natural copper outer wall

The outer wall is available in:

• AISI 304 BA stainless steel;
• natural copper in the relevant versions.

Main applications

According to De Marinis technical documentation, ISO25 PLUS can be used, in compatible configurations, with:

• wood-burning stoves;
• pellet stoves;
• fireplaces;
• atmospheric heat generators;
• pressurised appliances;
• forced-air generators;
• traditional heat generators;
• compatible condensing appliances;
• domestic and industrial kitchen hoods;
• compatible air-conveyance applications.

Available diameters

ISO25 PLUS is available with the following nominal internal diameters:

• Ø80 mm
• Ø100 mm
• Ø130 mm
• Ø150 mm
• Ø180 mm
• Ø200 mm
• Ø250 mm
• Ø300 mm
• Ø350 mm

The corresponding external diameters are Ø130, Ø150, Ø180, Ø200, Ø230, Ø250, Ø300, Ø350 and Ø400 mm.

ISO25 PLUS vs ISO25

Both systems use an AISI 316L inner wall, 25 mm insulation and an AISI 304 or copper outer wall.

The key difference is the certified high-temperature clearance from combustible materials:

In its certified configuration, ISO25 PLUS therefore reduces the required clearance from combustible materials from 85 mm to 50 mm.

How to choose ISO25 PLUS components

Before purchasing, check:

• the connected appliance;
• fuel type;
• required flue diameter;
• flue-gas temperature;
• positive- or negative-pressure operation;
• possible condensate formation;
• required clearance to combustible materials;
• indoor or outdoor installation;
• number of elbows and branches;
• required supports and roof-penetration accessories.

The G50 designation must be considered together with all other conditions specified by the certification. The 50 mm clearance is not a general rule applicable to every chimney installation.

Browse all ISO25 PLUS pipes, elbows, fittings and accessories below to configure the chimney system required for your installation.