Product Description

TWPro 125mm Twin Wall Connecting Pipe 500mm Matt Black

Model: 37-125-026

Connect a compatible heating appliance directly to a TWPro insulated chimney with the TWPro 125mm Twin Wall Connecting Pipe 500mm. This specialist starter length has an exposed telescopic connecting pipe built into its male end, allowing it to form a neat transition from the appliance to the insulated chimney system.

The supplied insulation and cover band conceal the exposed connection after installation. As a result, the finished chimney route has a clean and streamlined appearance without a long visible section of single-wall connecting pipe.

The telescopic disconnecting section also makes it easier to remove the appliance for servicing, replacement or maintenance. Therefore, this component provides both a neat visual finish and practical access.

Please note: Check the appliance outlet diameter and connection requirements before ordering. Although this component can connect directly to a compatible appliance, it will not suit every stove or boiler outlet without an additional adaptor.

Key Features

• 125mm internal flue diameter
• Nominal 500mm connecting-pipe length
• Designed as a starter length for a TWPro chimney
• Can connect directly to a compatible heating appliance
• Exposed telescopic connecting pipe built into the male end
• Disconnecting section helps with appliance removal
• Cover band conceals the telescopic connection
• Insulation included for the connecting section
• Creates a clean and streamlined stove installation
• Reduces the need for a long visible single-wall connection
• Durable matt-black outer finish
• 316L-grade stainless-steel inner casing
• 304-grade stainless-steel outer casing
• Push-fit TWPro connection with locking band
• Suitable for compatible solid-fuel, gas and oil appliances
• Forms part of a T600-rated insulated chimney system
• Compatible with TWPro and corresponding KW Flue components
• Product model: 37-125-026

TWPro 125mm Connecting Pipe Specification

Read: Why We Think TWPro Twin-Wall Flue Is the Best

• Download the TWPro Information Sheet
• Download the TWPro Installation Sheet
• Brand: TWPro
• Manufacturer: MI Flues
• Product type: adjustable appliance connecting pipe
• Nominal internal diameter: 125mm
• Approximate system external diameter: 175mm
• Nominal length: 500mm
• Connection design: exposed telescopic male connecting section
• Outer cover: removable cover band
• Inner casing: 0.4mm 316L-grade stainless steel
• Outer casing: 0.4mm 304-grade stainless steel
• Outer finish: high-temperature matt-black coating
• Insulation: high-density mineral wool with insulation for the connecting section
• System joint method: push fit with locking bands
• Maximum system temperature class: T600
• Minimum distance to combustible materials: 50mm under the T600 G50 classification
• Product model: 37-125-026

What Is Included?

• 1 x TWPro 125mm Twin Wall Connecting Pipe 500mm
• 1 x telescopic appliance connecting section
• 1 x insulation section for the exposed connection
• 1 x matt-black cover band
• 1 x compatible locking band
• Finish: matt black
• Model: 37-125-026

Application

This TWPro connecting pipe forms the first insulated section above a compatible heating appliance. Its telescopic male end enters or connects to the appliance outlet, while the upper end allows the chimney to continue in the TWPro twin-wall system.

It can form part of a correctly designed chimney serving compatible appliances such as:

• Wood-burning stoves
• Multifuel stoves
• Other suitable solid-fuel appliances
• Compatible gas appliances
• Compatible oil-fired appliances

Always check the appliance manufacturer’s instructions before ordering. In addition, confirm the required diameter, connection depth, flue direction and permitted chimney arrangement.

Direct Appliance Connection

The exposed telescopic section allows this pipe to connect directly to a compatible appliance outlet. This can create an immediate transition from the stove or boiler to insulated TWPro chimney.

Because the insulation and outer cover extend down around the connection, the final installation has a cleaner appearance than a route with a long section of visible single-wall pipe.

However, appliance outlets vary in size, depth and connection style. Therefore, measure the outlet carefully and check whether the appliance manufacturer permits a direct twin-wall connection.

Telescopic Disconnecting Section

The telescopic section provides movement at the appliance connection. As a result, an installer can disconnect the chimney from the appliance more easily when the stove or boiler needs servicing, maintenance or replacement.

This feature can avoid the need to dismantle a larger part of the chimney system. Nevertheless, the pipe must remain correctly secured and supported during normal operation.

Do not use the telescopic movement as a substitute for measuring and planning the chimney route correctly.

Cover Band and Insulated Connection

A cover band fits around the exposed connecting section to provide a neat outer finish. Insulation fills the area between the inner connecting pipe and outer cover.

The insulation must sit correctly around the connecting section without gaps. Therefore, follow the TWPro instructions when positioning the insulation and securing the cover band.

Do not operate the appliance with the insulation or cover band missing unless the manufacturer’s installation instructions specifically permit it.

Planning the First Chimney Length

The first section above an appliance affects the position of the entire chimney route. Therefore, check the appliance location, ceiling position, nearby walls and required support points before installation.

Also consider whether the chimney will:

• Continue vertically through the property and roof
• Use bends to create an internal offset
• Pass through an external wall before rising vertically
• Connect to another approved chimney or flue component

A correctly planned first length can help keep the chimney vertical, reduce unnecessary bends and simplify the position of later supports.

TWPro System Construction

• Inner casing: 0.4mm 316L-grade stainless steel
• Outer casing: 0.4mm 304-grade stainless steel
• Outer finish: matt-black high-temperature coating
• Insulation: high-density mineral wool
• Joint system: push fit with locking bands
• Maximum operating-temperature class: T600

The stainless-steel casings and insulation help retain heat inside the flue while limiting heat transfer to the chimney exterior. This construction also supports stable flue-gas temperatures within a correctly designed installation.

Approvals and System Classification

• HETAS-approved chimney system
• EN 1856-1 T600 N1 W V2 L50040 G50
• EN 1856-1 T200 P1 W V2 L50040 O20
• Suitable for compatible negative-pressure applications up to T600
• Suitable for compatible positive-pressure applications up to T200

The required classification depends on the appliance, fuel and complete chimney design. Therefore, check the classification and compatibility of every component before installation.

Distance to Combustible Materials

The declared minimum distance from the outside of the TWPro insulated chimney system to combustible materials is 50mm under its T600 G50 classification.

Maintain this clearance around the insulated outer casing. Do not fill the space with timber, insulation, plasterboard or another combustible material.

The appliance and its outlet may require different clearances from nearby materials. Therefore, always follow the largest distance stated in the appliance and chimney instructions.

Installation Guidance

• Confirm that the 125mm internal diameter suits the appliance
• Check that the appliance permits a direct twin-wall connection
• Measure the appliance outlet before ordering
• Confirm the required engagement depth
• Plan the complete chimney route before fitting the starter section
• Position the telescopic section correctly in the appliance outlet
• Fit the supplied insulation around the connecting section
• Secure the outer cover band as instructed
• Push each TWPro joint fully together
• Fit and secure every required locking band
• Provide all required chimney supports
• Do not allow the chimney weight to rest on the appliance outlet unless specifically permitted
• Maintain all required distances from combustible materials
• Follow the appliance and TWPro installation instructions
• Comply with Building Regulations and all relevant standards

This component forms part of a safety-critical chimney system. Therefore, a suitably competent installer should design and complete the installation. For solid-fuel systems, use a HETAS-registered installer where appropriate.

Appliance Outlet Compatibility

Some appliances have a socket designed to accept the male end of a connecting flue. However, outlet dimensions can vary even when the stated nominal diameter is the same.

Before ordering, check:

• The nominal appliance outlet diameter
• The measured internal or external outlet diameter
• Whether the outlet is male or female
• The available connection depth
• Whether sealing rope, fire cement or an adaptor is required
• Whether the appliance allows twin-wall chimney to start directly from its outlet

If the connecting pipe does not match the appliance outlet, use the correct approved stove adaptor rather than forcing or modifying the joint.

Supporting the Chimney

The connecting pipe starts the insulated chimney route, but it does not replace the system’s structural supports. The complete chimney may require base supports, wall brackets, ceiling supports, roof supports or guy-wire components.

Plan these supports before installation. The chimney must remain stable and should not place excessive vertical or sideways force on the appliance outlet.

Compatibility

This connecting pipe fits the 125mm TWPro and corresponding KW Flue systems only. Other twin-wall chimney brands use different diameters, joint profiles, insulation arrangements and locking methods.

Therefore, do not combine this pipe with another chimney system unless the manufacturer confirms compatibility in writing.

The stated 125mm measurement refers to the internal flue diameter. Since the TWPro system uses approximately 25mm of insulation around the inner casing, connected twin-wall pipe has an external diameter of approximately 175mm.

Inspection and Maintenance

Inspect the connecting pipe, telescopic section, insulation, cover band and locking bands during routine chimney maintenance. Check that the appliance connection remains secure and that no component has moved.

The telescopic section can help when the appliance needs removal. However, a competent person should disconnect and refit the chimney correctly before the appliance returns to service.

Arrange chimney sweeping at intervals that suit the appliance, fuel and frequency of use. Replace any component that becomes damaged, distorted, badly corroded or insecure.

TWPro Warranty

• 25-year system warranty, subject to the manufacturer’s terms and conditions
• 2-year warranty on the painted finish

Correct product selection, installation, fuel use and maintenance may affect warranty cover. Therefore, keep your proof of purchase and follow all manufacturer instructions.

Why Choose the TWPro Twin-Wall System?

TWPro combines a 316L stainless-steel inner casing with dense insulation and a durable matt-black outer casing. As a result, it provides a strong and neat chimney system for a wide range of compatible heating appliances.

Its push-fit connections and locking bands also help installers form secure joints. In the UK, the same system may carry the KW Flue name. However, always check the product codes and joint design before combining components.

Why Buy from SNH Tradecentre?

SNH Tradecentre works closely with MI Flues, the supplier behind the TWPro chimney system. Therefore, our team can check technical details, confirm stock and help you select the correct starter pipe, adaptors, fixed lengths and support components.

We also work closely with MI Flues to process orders quickly. As a result, we can often arrange same-day dispatch for eligible in-stock orders placed before the daily cut-off time. Stock and delivery times can vary, so please contact us if your order is urgent.

• Close working relationship with MI Flues
• Fast dispatch on eligible in-stock orders
• Nationwide UK delivery options
• Experienced stove and chimney product advice
• Extensive range of matching TWPro components
• Help checking appliance and system compatibility
• Secure online ordering
• Support before and after your purchase

If you need help confirming whether this connecting pipe will fit your appliance, contact SNH Tradecentre before ordering.

Frequently Asked Questions

What does this TWPro connecting pipe do?

It creates the first insulated chimney section above a compatible heating appliance. Its telescopic male end allows a direct connection while the insulation and cover band produce a neat finish.

Is this a standard fixed 500mm pipe?

No. It is a specialist 500mm connecting or starter pipe with a telescopic appliance connection. For a normal fixed 500mm TWPro length, select the appropriate standard pipe instead.

Can it connect directly to a wood-burning stove?

Yes, it can connect directly to a compatible stove outlet when the dimensions and appliance instructions allow it. Some stoves may still require a dedicated adaptor.

Why does the pipe have a telescopic section?

The telescopic section helps form the appliance connection and allows easier disconnection when the appliance needs servicing, maintenance or replacement.

Does it include the cover band and insulation?

Yes. The connecting pipe includes insulation and a cover band for the exposed telescopic section.

Does it include a locking band?

Yes. A compatible locking band comes with the pipe for its TWPro system connection.

What diameter is the pipe?

The nominal internal flue diameter is 125mm, which is approximately 5 inches. The external diameter of the connected twin-wall system is approximately 175mm.

Can I use it with gas and oil appliances?

It can form part of compatible gas and oil chimney systems. However, the appliance manufacturer and installer must confirm the required diameter, pressure class and connection method.

Can this pipe pass through a wall or ceiling?

TWPro is an insulated chimney system, but every building penetration still requires the correct firestop, support and other approved components. Do not use the connecting pipe as a substitute for those parts.

How far must it remain from combustible materials?

The declared minimum clearance from the TWPro insulated chimney is 50mm under the T600 G50 classification. The appliance connection or another part of the installation may require a greater clearance.

Will it fit another brand of twin-wall chimney?

No compatibility should be assumed. This component fits the 125mm TWPro and corresponding KW Flue systems. Do not mix chimney brands unless the manufacturer confirms compatibility in writing.

What is the model number?

The model number for the TWPro 125mm Connecting Pipe 500mm is 37-125-026.