Product Description

TWPro 125mm Twin Wall Insulated 90 Degree Tee Matt Black

Model: 37-125-035

Connect a rear-outlet appliance to a vertical insulated chimney with the TWPro 125mm Twin Wall 90 Degree Tee. The side branch accepts the horizontal flue connection, while the upper outlet allows the TWPro chimney to continue vertically.

The lower opening provides a position for a suitable removable tee cap. As a result, the installer can include access for chimney sweeping, inspection and the removal of combustion deposits.

Please note: A tee cap does not come with this product. Order the standard TWPro 125mm Tee Cap, model 37-125-036, or a compatible cap with a drain if the installation requires one.

Key Features

• 125mm internal flue diameter
• 90-degree insulated chimney tee
• Suitable for connecting compatible rear-outlet appliances
• Allows the chimney to continue vertically above the connection
• Lower opening accepts a compatible removable tee cap
• Provides a practical point for sweeping and inspection
• Durable matt-black finish
• Manufactured with stainless-steel inner and outer casings
• Push-fit connection system with locking bands
• 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: 37-125-035

TWPro 125mm 90 Degree Tee Specification

• Download the TWPro Information Sheet
• Download the TWPro Installation Sheet
• Brand: TWPro
• Manufacturer: MI Flues
• Product type: insulated 90-degree chimney tee
• Nominal internal diameter: 125mm
• Approximate system external diameter: 175mm
• Angle: 90 degrees
• Finish: matt black
• Typical application: rear appliance outlet to vertical chimney
• Connection system: push fit with locking bands
• Maximum system temperature class: T600
• Product model: 37-125-035

What Is Included?

• 1 x TWPro 125mm Twin Wall Insulated 90 Degree Tee
• 1 x compatible locking band
• Finish: matt black
• Model: 37-125-035

Tee cap not included: A compatible 125mm tee cap must be ordered separately for the lower opening. Standard and drain-cap versions are available for different installation requirements.

Application

The TWPro 90-degree tee usually connects a compatible rear-outlet appliance to a vertical twin-wall chimney. The horizontal branch receives the appliance connection, while the upper section carries the flue gases upwards through the main chimney route.

This tee 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 chimney diameter, connection type and permitted flue arrangement.

Connecting a Rear-Outlet Stove

A rear-outlet stove often needs a 90-degree change of direction before the chimney can rise vertically. This tee provides the horizontal connection and vertical chimney route within one component.

However, some appliances require a section of single-wall connecting pipe between the stove and the insulated chimney. Others may need a dedicated appliance adaptor. Therefore, do not assume that the tee can connect directly to every stove outlet.

Check the stove outlet size and appliance instructions before choosing the required adaptors and connecting components.

Sweeping and Inspection Access

The lower opening of the tee allows the installer to add a removable tee cap. Once fitted, the cap can provide access to the base of the vertical chimney for sweeping and inspection.

This access also helps with the removal of soot and other deposits that collect at the base of the chimney. Therefore, keep the cap accessible after installation and do not hide it behind permanent building finishes.

Choose from the following compatible options:

• TWPro 125mm standard tee cap
• TWPro 125mm tee cap with drain, where required by the chimney design

The tee cap is a separate product and does not come with model 37-125-035.

Planning a 90-Degree Flue Connection

A 90-degree tee creates a greater change in direction than a shallow bend. Therefore, it can affect the chimney draught and may collect more deposits than a straighter route.

For chimney-route and cleaning calculations, a factory-made 90-degree tee may count as two 45-degree changes of direction. The installer must confirm that the complete route follows the appliance instructions and current Building Regulations.

Where possible, keep the rest of the chimney route straight and vertical. Also make sure that the tee cap remains easy to reach for cleaning.

TWPro System Construction

• Inner casing: 0.4mm 316L-grade stainless steel
• Outer casing: 0.4mm 304-grade stainless steel
• Outer finish: matt-black powder coating
• Insulation: 25mm injected mineral wool
• Insulation density: 190kg/m³
• Joint system: push fit with locking band
• Maximum operating-temperature class: T600

The stainless-steel casings and mineral-wool insulation help maintain the flue temperature while reducing heat transfer to the outside of the chimney.

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.

Keep this clearance around the complete tee, including its horizontal branch and vertical outlets. Do not fill the space with timber, insulation, plasterboard or another combustible material.

The appliance or another part of the installation may require a greater distance. Therefore, always follow the largest clearance stated in the appliance and chimney instructions.

Installation Guidance

• Confirm that the appliance manufacturer allows a 90-degree tee connection
• Check that the 125mm internal diameter suits the appliance
• Plan the position of the tee before assembling the chimney
• Keep the main chimney route as straight and vertical as possible
• Support the tee and connected chimney correctly
• Do not allow the tee to place excessive weight on the appliance outlet
• Push each compatible joint fully together
• Fit and secure every required locking band
• Install a compatible cap on the lower tee opening
• Keep the tee cap accessible for sweeping and inspection
• Maintain at least 50mm from combustible materials
• Follow the appliance and TWPro installation instructions
• Comply with Building Regulations and relevant standards

This tee 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.

Compatibility

This tee fits the 125mm TWPro and corresponding KW Flue systems only. Other twin-wall chimney brands use different dimensions, joint profiles and locking methods.

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

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

Inspection and Maintenance

Inspect the tee, locking bands and support components during routine chimney maintenance. Also remove the tee cap when required to clear soot and deposits from the base of the chimney.

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 mineral-wool insulation and a durable matt-black outer casing. As a result, it provides a neat and strong 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 tee cap, adaptors 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 product and system compatibility
• Secure online ordering
• Support before and after your purchase

If you need help choosing a tee cap or planning a rear-outlet chimney connection, contact SNH Tradecentre before ordering.