Insulated Twin-Wall Stainless Steel Chimney Systems

Twin-wall stainless steel chimney systems are modular flue systems designed for combustion-product evacuation where greater thermal protection is required than with a single-wall chimney liner.

This category includes De Marinis ISOAIR, ISO10, ISO25 and ISO50 systems, available with different insulation thicknesses, diameters and external finishes.

The correct system depends on the connected appliance, flue-gas temperature, required diameter, chimney position, clearance from combustible materials and overall installation conditions.

Which twin-wall chimney system should you choose?

Why use an insulated twin-wall chimney?

An insulated twin-wall chimney reduces heat loss from flue gases compared with an uninsulated single-wall pipe and provides greater thermal protection to the surrounding area.

Typical applications include:

• external chimney installations along building façades;
• chimneys running through cold or unheated spaces;
• new chimney systems without an existing masonry shaft;
• wall and roof penetrations using suitable components;
• installations requiring increased thermal protection.

ISOAIR – air-insulated twin-wall system

ISOAIR uses a twin-wall construction with an air gap instead of mineral-wool insulation.

The inner wall is made of AISI 316 stainless steel, while the outer wall of the stainless version is AISI 304 BA stainless steel.

Its compact construction helps minimise the overall external diameter of the chimney.

ISO10 – 10 mm insulated chimney system

ISO10 uses 10 mm of high-density mineral wool insulation.

The stainless steel version combines an AISI 316 inner wall with an AISI 304 BA outer wall, providing an insulated system with reduced overall dimensions.

The range is also available with matt black, Rusty and hammered-copper-effect finishes for visible installations.

ISO25 – 25 mm insulated chimney system

ISO25 uses 25 mm of high-density mineral wool and is one of the most versatile systems in the De Marinis range.

The system includes straight pipes, elbows, T-connectors, telescopic sections, support plates, terminals and installation accessories.

ISO50 – high thermal insulation

ISO50 provides the greatest insulation thickness within this group and is designed for installations requiring increased thermal protection.

It is particularly suited to demanding flue conditions, high flue-gas temperatures and installations where greater separation from surrounding materials is required.

Available finishes

• Stainless steel;
• Matt black;
• Rusty effect;
• Hammered copper effect.

Finish availability depends on the selected ISO10 or ISO25 range and individual component.

Available components

Depending on the selected system, the range includes:

• straight chimney pipes;
• telescopic elements;
• elbows;
• T-connectors;
• inspection components;
• caps and condensate drains;
• support plates and brackets;
• wall support collars;
• weatherproof and anti-wind terminals;
• roof-penetration and installation accessories.

Twin-wall or single-wall chimney?

The choice between a single-wall and insulated twin-wall chimney depends on the location and operating conditions of the flue.

Single-wall systems are generally used inside protected chimney shafts or technical ducts, while insulated twin-wall systems are commonly used outdoors, through cold areas or where the chimney remains directly exposed.

How to choose the correct system

Before purchasing, consider:

• the connected appliance;
• fuel type;
• required flue diameter;
• flue-gas temperature;
• positive- or negative-pressure operation;
• possible condensate formation;
• indoor or outdoor installation;
• clearance from combustible materials;
• available installation space;
• required external finish.

Browse the ISOAIR, ISO10, ISO25 and ISO50 ranges below to select the most appropriate insulated twin-wall chimney system and compatible pipes, fittings and accessories.