Schiedel

Schiedel Isokern Pumice Chimney Systems

Schiedel is one of the leading manufacturers of chimney and flue systems, with solutions for wood-burning stoves, fireplaces, open fires, gas appliances and new chimney construction.

Bonfire is a UK Schiedel dealer and has extensive practical experience designing, supplying and installing chimney systems. Our current collection has a particular focus on Schiedel Isokern, a modular chimney system manufactured from naturally insulating volcanic pumice.

Products are available individually or as complete packages, allowing homeowners, installers, builders and developers to specify the chimney around the appliance and building rather than assembling unrelated components.

Why Use a Pumice Chimney?

Pumice is naturally insulating. Within a chimney this helps the flue gases reach and maintain an effective operating temperature, supporting chimney performance while reducing heat loss through the chimney structure.

Schiedel’s Isokern systems are lightweight compared with many traditional masonry chimney constructions and can be used in both new-build and refurbishment projects.

Typical applications include:

• New masonry chimneys
• Wood-burning stove installations
• Traditional fireplaces and open fires
• Extensions and new-build properties
• Relining and rebuilding existing chimneys
• Timber-frame and steel-frame construction
• Indoor and outdoor fireplace projects

Isokern Pumice Chimney Liners

Schiedel Isokern pumice liners can be used to construct new flues or refurbish suitable existing chimney structures.

Bonfire currently offers complete liner bundles in popular internal diameters including:

The correct diameter must be selected according to the appliance, fireplace opening and chimney design. A larger flue is not automatically better, as excessive diameter can reduce flue-gas velocity and affect performance.

Schiedel Isokern Double Module Chimneys

The Isokern Double Module (DM) system is a complete twin-wall masonry chimney rather than simply a liner.

Its inner flue and outer casing are separated, helping maintain flue-gas temperature while reducing heat transfer to the surrounding chimney structure. The separate components can also accommodate thermal movement, helping reduce the risk of cracking.

Schiedel offers different DM sizes for different applications:

• DM36 – 150mm internal diameter for many stoves, cookers and smaller-output appliances
• DM44 – 180mm or 200mm internal diameters for larger stoves, inserts and smaller open fires
• DM54 – 300mm or 345mm internal diameters for larger open fires and high-volume applications

Bonfire currently offers complete DM36 chimney packages in several heights, making specification simpler than ordering every block and component separately.

Pumice Liner or Complete DM Chimney?

The correct system depends largely on what already exists within the property.

A pumice liner system can be suitable where a masonry chimney structure is being constructed or an appropriate existing chimney needs refurbishment.

A Double Module chimney creates the complete insulated chimney structure and can be particularly useful in new-builds, extensions and projects where there is no existing chimney.

For some stove installations, an insulated stainless-steel twin-wall chimney may instead be more appropriate. The building construction, appliance, chimney route and desired finish should determine the system rather than price alone.

Schiedel Firebacks & Fireplace Components

The Isokern range also includes components for traditional fireplace construction, including Milner firebacks, firebricks, chimney blocks, offset components and reinforcement products.

This allows the fireplace opening and chimney above it to be designed as one coordinated system.

Schiedel’s Magnum Firechest system can also be used to create substantial open-fire openings, including fireplaces up to approximately 1.2 metres wide.

Schiedel Garden Fireplaces

Schiedel applies the same natural pumice technology to its Isokern Garden Fireplace collection.

These fireplaces arrive as packaged masonry systems and create a permanent outdoor focal point rather than a portable fire pit. Pumice provides the insulating structure around the firebox and chimney.

Different sizes allow the fireplace to be incorporated into patios, terraces and outdoor kitchens, with larger models creating a substantial architectural feature.

Because they use a proper chimney to direct smoke upwards, they provide a very different outdoor-fire experience from an open fire bowl.

Choosing the Correct Chimney Diameter

Chimney sizing should never be based purely on the diameter of the appliance outlet.

The correct specification can depend on:

• Appliance type and output
• Manufacturer’s required flue diameter
• Open-fire dimensions
• Total chimney height
• Number and angle of offsets
• Internal or external chimney route
• Terminal position
• Surrounding building construction

Open fireplaces in particular often require considerably larger flues than closed wood-burning stoves.

Schiedel Chimney Design & Installation by Bonfire

A chimney is part of the heating appliance’s operating system, so correct design is essential for safe and reliable performance.

Bonfire can provide a complete chimney and fireplace design service, including:

• Site and home surveys
• Appliance and fireplace specification
• Chimney diameter calculations
• Pumice chimney design
• Existing chimney refurbishment
• New chimney construction
• Twin-wall chimney alternatives
• Fireplace and hearth construction
• Professional installation and commissioning

For complex projects, we recommend establishing the chimney system before finalising building work, roof penetrations or fireplace dimensions.

Why Buy Schiedel from Bonfire?

Bonfire does more than sell individual chimney components. Our team works with fireplaces, appliances and flue systems every day, allowing us to consider how the complete system will operate together.

• Approved UK Schiedel dealer
• Supply-only or professional installation
• Complete Isokern pumice packages
• Individual replacement and construction components
• Technical chimney-system advice
• Residential and commercial project experience
• Installation across the South East, including London

Schiedel FAQs

What is an Isokern chimney?

Isokern is Schiedel’s modular chimney range manufactured using naturally insulating volcanic pumice. It includes chimney liners, complete Double Module chimney systems, firechests and associated components.

Can Isokern be used for a new chimney?

Yes. Isokern systems can be used for new chimney construction as well as suitable refurbishment and relining projects.

What size pumice liner do I need for a wood-burning stove?

Many stove installations use a 150mm flue, but the correct diameter must be confirmed against the appliance manufacturer’s requirements and the complete chimney design.

What is the difference between Isokern liner and DM?

An Isokern liner forms the internal flue within a suitable chimney construction. The Double Module system includes both an inner pumice flue and outer pumice casing to create the complete insulated chimney.

Can Schiedel chimneys be installed externally?

Isokern systems can be used internally or externally where the system design, weather protection, clearances and manufacturer’s installation requirements are correctly followed.

Does Schiedel make outdoor fireplaces?

Yes. Schiedel produces Isokern Garden Fireplaces using its insulating pumice construction, with several sizes available for patios, terraces and outdoor-kitchen projects.

Can Bonfire design and install my Schiedel chimney?

Yes. Bonfire supplies and installs chimney and flue systems and can advise on chimney sizing, routing, fireplace construction and the most appropriate system for the proposed appliance.