Product Description

TWPro 125mm Twin Wall Insulated Flat Adaptor – Matt Black

Model: 37-125-005

Create a short and neat transition from a 125mm appliance outlet or single-wall stove pipe to a 125mm TWPro insulated chimney with this TWPro Twin Wall Flat Adaptor.

Unlike a tapered adaptor, its flat design changes from single wall to twin wall almost immediately. Therefore, it provides a useful solution when the installation has limited vertical space above the appliance.

The adaptor can connect directly to a compatible appliance outlet. Alternatively, it can connect 125mm vitreous enamel or another approved single-wall connecting pipe to the TWPro twin-wall chimney system.

Product at a Glance

• 125mm nominal internal flue diameter
• Connects single-wall pipe to 125mm TWPro twin wall
• May connect directly to a compatible appliance outlet
• Flat design creates a short, immediate transition
• No change in nominal internal flue diameter
• Ideal where installation height is limited
• Matt-black external finish
• 316L stainless-steel inner casing
• 304-grade stainless-steel outer casing
• High-density mineral wool insulation
• Push-fit TWPro connection
• Supplied with a locking band
• Suitable for compatible solid-fuel, gas and oil appliances
• HETAS approved and CE marked
• T600 temperature classification
• G50 soot-fire resistance classification
• 50mm declared distance to combustible materials
• Product model: 37-125-005

What Does This Flat Adaptor Connect?

This component creates a transition between:

• A compatible 125mm appliance outlet and 125mm TWPro twin wall
• 125mm vitreous enamel stove pipe and 125mm TWPro twin wall
• Another approved 125mm single-wall connecting pipe and 125mm TWPro twin wall

Both sides have a nominal internal flue diameter of 125mm. Therefore, the adaptor changes the construction from single wall to insulated twin wall without increasing or reducing the internal flue size.

The 125mm measurement refers to the internal flue diameter. Because the TWPro section contains insulation and an outer casing, its overall outside diameter will be larger than 125mm.

Why Choose a Flat Adaptor?

A standard adaptor often uses a longer tapered section to change from single wall to twin wall. In contrast, this flat adaptor creates the transition over a much shorter height.

As a result, it can help when the available distance between the appliance and the start of the insulated chimney is limited. It also creates a clean, compact appearance above the stove.

The flat shape does not increase or reduce the flue diameter. Therefore, choose this model when both the appliance or connecting pipe and the TWPro chimney use a 125mm internal diameter.

Key Features

• Compact alternative to a longer tapered stove adaptor
• Creates an immediate transition into insulated twin wall
• Helps reduce the overall height of the connecting arrangement
• Maintains a 125mm internal flue route
• Reduces the number of separate components required
• Suitable for compatible appliance outlets and connecting pipes
• Fully welded construction provides strength and durability
• Insulated upper section helps retain flue temperature
• Matt-black finish complements most black stoves and stove pipes
• Supplied locking band secures the TWPro joint

TWPro 125mm Flat Adaptor Specification

• Download the TWPro Matt Black information sheet
• View the TWPro installation diagram
• Read why we recommend TWPro twin-wall flue
• Product type: flat single-wall to twin-wall adaptor
• Nominal internal diameter: 125mm
• Lower connection: compatible 125mm appliance outlet or single-wall pipe
• Upper connection: 125mm internal-diameter TWPro twin wall
• Internal diameter change: none
• 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 compressed mineral wool
• Construction: fully welded
• Joint method: push fit with locking band
• Locking band: included
• Temperature classification: T600
• Declared distance to combustible materials: 50mm
• System warranty: 25 years, subject to terms and conditions
• Paint-finish warranty: 2 years, subject to terms and conditions
• Product code: 37-125-005

Approvals and Classifications

• HETAS approved
• CE marked
• EN 1856-1 T600 N1 W V2 L50040 G50
• EN 1856-1 T200 P1 W V2 L50040 O20

The T600 designation classifies the relevant chimney arrangement for flue-gas temperatures up to 600°C. In addition, the G50 designation identifies a soot-fire-resistant arrangement with a declared distance of 50mm from combustible materials.

However, the correct classification depends on the appliance, fuel and complete chimney design. Therefore, always follow the appliance instructions and TWPro installation guide.

Suitable Applications

This TWPro 125mm flat adaptor may suit correctly specified heating appliances such as:

• Wood-burning stoves
• Multifuel stoves
• Compatible solid-fuel appliances
• Gas coal-effect fires
• Gas appliances
• Oil-fired boilers
• Other compatible oil appliances

However, this list does not confirm suitability for every appliance. First, check that the appliance requires a 125mm flue. Next, confirm the outlet or connecting-pipe dimensions. Finally, make sure the complete chimney carries the correct classification for the appliance and fuel.

Can It Connect Directly to a Stove?

Yes, the flat adaptor can connect directly to some compatible 125mm appliance outlets. This arrangement allows the insulated chimney to start close to the appliance and keeps the transition as short as possible.

However, nominally identical stove outlets can use different internal diameters, external diameters and socket depths. Therefore, check the appliance spigot and adaptor dimensions before ordering.

The appliance manufacturer must also allow a direct twin-wall connection. If the instructions require a length of single-wall connecting pipe above the appliance, follow that requirement.

Can It Connect to Vitreous Enamel Stove Pipe?

Yes. The lower end can connect to compatible 125mm vitreous enamel stove pipe or another approved single-wall connecting pipe.

This allows the installer to use a visible single-wall section above the stove before changing to insulated TWPro. However, the joint sizes and connection direction must match.

Do not force together components that do not fit correctly. Instead, confirm the actual joint dimensions and system compatibility before installation.

Flat Adaptor or Tapered Adaptor?

Choose the flat adaptor when you need a short transition and both sides use a 125mm internal diameter. Its compact shape saves vertical space and creates an immediate change from single wall to twin wall.

In contrast, a tapered adaptor creates the transition over a longer section. An increasing adaptor may also change the internal flue diameter where the appliance outlet and chimney use different sizes.

Therefore, check these three points before ordering:

• Does the appliance or single-wall pipe have a 125mm connection?
• Does the chimney use 125mm internal-diameter TWPro?
• Does the installation need a compact flat transition?

Single Wall and Twin Wall Explained

Single-wall stove pipe has one steel wall and no insulation. Installers normally use it as a visible connecting pipe between the appliance and chimney.

In contrast, TWPro uses an inner flue, mineral wool insulation and a stainless-steel outer casing. The insulation helps maintain the flue-gas temperature while reducing heat transfer to the outside of the chimney.

Therefore, TWPro can form a chimney route through or close to building structures when installers use the correct supports, fire stops, flashings and clearances.

Single-wall stove pipe must not pass through walls, ceilings, floors, roofs or concealed spaces. The transition to insulated twin wall must take place before any building penetration and in the position required by the manufacturer’s instructions.

Strong Stainless-Steel Construction

The inner casing uses corrosion-resistant 316L-grade stainless steel. Meanwhile, the outer casing uses 304-grade stainless steel with a high-temperature matt-black finish.

High-density mineral wool surrounds the inner flue in the insulated section. As a result, the adaptor helps retain heat as the combustion gases enter the twin-wall chimney.

The fully welded construction also provides strength and durability. Consequently, the adaptor can form a reliable transition when installers fit, support and maintain it correctly.

Installation Guidance

First, confirm that the lower connection fits the appliance outlet or single-wall pipe. Next, fit the adaptor in the correct condensate-flow direction. Then connect the upper end to a compatible 125mm TWPro chimney section.

Push the TWPro joint fully together and secure it with the supplied locking band. Afterwards, check that the joint remains straight and fully engaged.

The flat adaptor does not support the weight of the full chimney. Therefore, use the correct wall supports, ceiling supports, roof supports and structural components throughout the installation.

Finally, follow the appliance instructions, TWPro installation guide, Building Regulations and all other relevant standards. We recommend installation by a suitably competent person.

Which Way Up Should It Be Installed?

Fit the single-wall or appliance connection at the bottom, towards the heating appliance. The insulated TWPro connection sits above it and continues into the chimney.

Correct orientation also helps keep condensate and combustion deposits inside the flue. Therefore, make sure every component follows the joint direction stated in the manufacturer’s instructions.

Distance to Combustible Materials

Maintain at least 50mm between the TWPro insulated chimney and combustible materials for the relevant T600 G50 arrangement.

Combustible materials can include timber, roof structures, insulation, furniture and other heat-sensitive products. Furthermore, plasterboard may form part of a timber structure and should not automatically count as non-combustible.

The appliance outlet or single-wall pipe may require a greater clearance than the insulated TWPro section. Therefore, apply the correct clearance to each part and follow the greatest requirement where clearances overlap.

Does It Include a Locking Band?

Yes. The manufacturer supplies a locking band with this flat adaptor. The band secures the push-fit joint between the adaptor and the next TWPro chimney component.

Fully engage the joint before closing the locking band. In addition, check that the band remains secure and correctly positioned after installation.

Can I Mix TWPro with Another Chimney Brand?

Do not connect this adaptor to another manufacturer’s twin-wall chimney unless both manufacturers provide written approval.

Different systems can use different outer diameters, joint depths, insulation specifications and locking methods. Therefore, components with the same stated internal diameter may not connect safely.

Using matching TWPro components helps preserve the tested system classification and provides a secure, consistent installation.

Maintenance and Inspection

Inspect the adaptor and joints during routine chimney maintenance. Check the locking band, matt-black surface and lower connection for movement, damage or corrosion.

Also, arrange chimney sweeping at intervals that suit the appliance, fuel and frequency of use. The complete system must provide suitable access for inspection and cleaning.

Replace the adaptor if it becomes badly corroded, distorted, damaged or insecure. Furthermore, arrange a professional inspection if you notice smoke leakage, staining or a change in chimney performance.

Why Choose TWPro?

TWPro combines a durable 316L stainless-steel inner flue with a strong 304-grade stainless-steel outer casing. In addition, the mineral wool insulation helps the chimney retain heat and maintain a stable flue temperature.

The push-fit joint system makes assembly straightforward, while the locking band secures each connection. Furthermore, the extensive range of matching pipes, bends, tees, supports, flashings and terminals allows installers to create a complete chimney from compatible components.

Finally, the smooth matt-black finish creates a professional appearance above modern and traditional stoves.

Why Buy from SNH Tradecentre?

• Specialist stove, chimney and flue-system supplier
• Extensive range of matching 125mm TWPro components
• Practical advice from an experienced team
• Nationwide UK delivery options
• Secure online ordering
• Trade counter in Birchington, Kent
• Support before and after your purchase

Need help checking your appliance outlet or matching chimney components? Call SNH Tradecentre on 01843 842727 before ordering.

Frequently Asked Questions

What does this flat adaptor connect?

It connects a compatible 125mm appliance outlet, vitreous enamel pipe or other approved single-wall pipe to a 125mm internal-diameter TWPro chimney.

Does this adaptor change the flue diameter?

No. It maintains a nominal 125mm internal flue diameter while changing from single-wall to insulated twin-wall construction.

Why is it called a flat adaptor?

Its compact design creates an almost immediate transition from single wall to twin wall. Therefore, it uses less vertical space than a longer tapered adaptor.

Can I connect it directly to a wood-burning stove?

Yes, it may connect directly to a compatible 125mm stove outlet. However, check the outlet dimensions and appliance instructions before ordering.

Can it connect to vitreous enamel stove pipe?

Yes, it can connect to compatible 125mm vitreous enamel or another approved single-wall connecting pipe.

Does the adaptor include a locking band?

Yes. The supplied locking band secures the upper TWPro push-fit connection.

Is 125mm the outside diameter of the twin-wall section?

No. The 125mm measurement refers to the internal flue diameter. The insulation and outer casing make the overall diameter larger.

How far must it remain from combustible materials?

The relevant insulated T600 G50 arrangement has a declared distance of 50mm from combustible materials. However, the single-wall connection or appliance may require a greater clearance.

Can the single-wall connection pass through a ceiling?

No. Single-wall pipe must not pass through walls, ceilings, floors, roofs or concealed spaces. The transition to insulated chimney must occur before the building penetration.

Can I connect it to another twin-wall chimney brand?

Do not mix chimney brands unless both manufacturers provide written approval. Similar-looking components may use incompatible joints.

What is the product model?

The product model is 37-125-005.