Product Description

TWPro 125mm Twin Wall Cone Top Cowl – Matt Black

Model: 37-125-093

Complete your insulated chimney with the TWPro 125mm Twin Wall Cone Top Cowl. This open flue terminal creates a clear, low-resistance exit for combustion gases. As a result, it helps the flue gases leave the chimney at a high exit velocity.

The cowl connects directly to compatible 125mm TWPro twin-wall flue components. In addition, its matt-black outer surface matches the rest of the TWPro black chimney range.

Please note: this is an open terminal rather than a rain cap. Therefore, rainwater can enter the chimney. Only use it on a correctly designed system with a suitable tee cap and drain or another approved drainage arrangement.

Product at a Glance

• 125mm internal flue diameter
• Open cone-top chimney terminal
• Creates a low-resistance flue-gas outlet
• Helps maintain a high flue-gas exit velocity
• Matt-black external finish
• 316L stainless-steel inner casing
• 304-grade stainless-steel outer casing
• High-density mineral wool insulation
• Suitable for compatible solid-fuel, oil and gas appliances
• Push-fit connection with a locking band
• T600 temperature classification
• G50 soot-fire resistance classification
• 50mm declared distance to combustible materials
• Product model: 37-125-093

What Is a Cone Top Cowl?

A cone top cowl is an open chimney terminal that fits at the top of a twin-wall flue system. Unlike a conventional rain cap, it does not place a hood above the flue outlet. Consequently, the terminal creates very little resistance to the escaping flue gases.

This simple design allows combustion gases to leave the chimney freely. Therefore, installers often choose an open cone top where a clear, unrestricted terminal suits the appliance and chimney design.

However, this product does not provide protection from rain. It also does not act as an anti-downdraught cowl or bird guard. You should select the terminal according to the appliance instructions, site conditions and complete chimney design.

Why Does the Chimney Need a Drain?

Because the top remains open, rainwater can fall directly into the chimney. Therefore, the system must provide a safe way to collect and discharge that water.

For example, many installations use a tee at the base of the vertical chimney together with a compatible tee cap and condensate drain. The drain then directs water away from the appliance and connecting flue.

Do not install this cone top on a system that cannot safely drain incoming rainwater. Water must not collect inside the chimney or run into the heating appliance.

Key Features

• Open construction for minimal terminal resistance
• Designed to maximise the available flue-gas exit area
• Compatible with the TWPro 125mm insulated chimney range
• Supplied in a smooth matt-black finish
• Strong stainless-steel internal and external casings
• Insulated construction helps maintain flue temperature
• Fully welded construction for strength and durability
• Simple push-fit assembly
• Locking-band connection helps secure the joint
• Suitable for internal or external chimney systems when correctly specified

TWPro 125mm Cone Top Cowl Specification

• Download the TWPro Matt Black information sheet
• View the TWPro installation diagram
• Read why we recommend TWPro twin-wall flue
• Product type: open cone-top chimney terminal
• Nominal internal diameter: 125mm
• Inner casing: 0.4mm 316L-grade stainless steel
• Outer casing: 0.4mm 304-grade stainless steel
• Outer finish: high-temperature matt-black coating
• Insulation: 25mm high-density mineral wool
• Joint method: push fit with locking band
• Maximum 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

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 system arrangement for flue-gas temperatures up to 600°C. In addition, the G50 designation identifies a soot-fire-resistant system with a declared 50mm distance to combustible materials.

However, the correct classification depends on the appliance, fuel, operating conditions and complete chimney arrangement. Therefore, always follow the appliance and TWPro installation instructions.

Application

This 125mm cone top cowl forms the terminal of a compatible TWPro insulated twin-wall chimney. It may suit correctly specified wood-burning stoves, multifuel stoves, gas appliances, oil appliances and other approved heating equipment.

First, check that the appliance requires a 125mm internal flue diameter. Next, confirm that an open terminal suits the appliance and installation location. Finally, make sure the chimney includes a suitable rainwater and condensate drainage point.

Do not mix this terminal with another manufacturer’s chimney system unless both manufacturers provide written approval. Twin-wall systems can use different joint designs and dimensions, even when they share the same stated internal diameter.

Open Cone Top or Rain Cap?

An open cone top gives the flue gases a direct exit and creates very little resistance. Therefore, it can support a strong exit velocity when the chimney has the correct height, diameter and design.

In contrast, a rain cap places a cover above the outlet to reduce direct rain entry. However, that cover also changes the way gases leave the terminal.

Neither option suits every installation. For this reason, consider local weather, exposure, appliance requirements, chimney position and drainage before choosing a terminal.

Installation Guidance

Fit the cone top to the final vertical section of compatible TWPro twin-wall chimney. Push the parts fully together and secure the connection with the correct locking band. Then check that the joint remains straight, stable and fully engaged.

The terminal must remain vertical and adequately supported. However, do not rely on the terminal or locking band to support the chimney below it. Instead, use the correct wall supports, roof supports and structural components throughout the system.

Before fitting the cowl, confirm that the chimney has an effective drainage arrangement. A suitable tee cap and drain will often provide this function at the base of an external vertical system.

Finally, position the terminal in accordance with the appliance instructions, the TWPro installation guide and Building Regulations. Chimney height and location can affect draught, nearby openings and the safe dispersal of combustion gases.

Distance to Combustible Materials

Maintain at least 50mm between the TWPro insulated chimney and combustible materials, subject to the certified system arrangement. Combustible materials may include timber, roof structures, insulation, furniture and other heat-sensitive products.

However, some appliances or installation details may require a greater distance. Therefore, follow the largest clearance stated in the appliance instructions, chimney instructions or relevant regulations.

Do not fill the required air gap with insulation or other materials unless the manufacturer provides a tested component specifically for that purpose.

Weather and Site Conditions

This cone top remains open to the weather. As a result, wind-driven rain, snow and debris may enter the chimney. A working drainage point is therefore essential.

Furthermore, an open terminal does not guarantee protection from downdraught. Exposed sites, nearby buildings, trees and complex roof shapes can affect airflow around the chimney. If the property has known wind or draught problems, ask a competent installer to assess the site before ordering.

Maintenance and Inspection

Inspect the terminal regularly and remove any visible blockage or debris. In addition, check the locking band, supporting components and matt-black finish for damage or movement.

You should also inspect and clean the system at intervals that suit the appliance, fuel and frequency of use. During servicing, confirm that the tee cap and drain remain clear. This step allows rainwater and condensate to leave the chimney safely.

Replace any component that becomes damaged, badly corroded, distorted or insecure. Also, arrange a professional inspection if you notice water entering the appliance, smoke leakage or a change in chimney performance.

Why Choose TWPro?

TWPro combines a 316L stainless-steel inner casing with a coated 304-grade stainless-steel outer casing. Meanwhile, the mineral wool insulation helps the flue retain heat as gases travel through the chimney.

The push-fit joint system also makes assembly straightforward. Once the sections engage, the locking band secures the connection. In addition, the smooth matt-black finish creates a smart appearance for visible chimney sections.

TWPro offers a wide range of compatible pipes, bends, tees, supports, flashings and terminals. Therefore, installers can build a complete chimney system from matching components.

Why Buy from SNH Tradecentre?

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

Need help choosing the correct terminal or drainage components? Call SNH Tradecentre on 01843 842727 before ordering.

Frequently Asked Questions

What diameter is this cone top cowl?

It fits the TWPro system with a nominal internal flue diameter of 125mm. Always check the system brand and diameter before ordering.

Does this cowl stop rain entering the chimney?

No. It is an open cone-top terminal, so rainwater can enter the chimney. Therefore, the installation needs a suitable tee cap and drain or another approved drainage arrangement.

What is the advantage of an open cone top?

The open design places very little resistance above the flue outlet. Consequently, combustion gases have a clear exit from the chimney.

Is this an anti-downdraught cowl?

No. This terminal does not specifically prevent downdraught. Ask a competent installer to assess exposed sites or existing wind-related problems.

Does it include a bird guard?

No. The open outlet does not contain a mesh bird guard. Choose a different approved terminal if the installation needs one.

Can I use it with a wood-burning stove?

Yes, it can suit compatible wood-burning and multifuel stoves. However, the appliance must permit a 125mm flue and the complete system must meet its installation requirements.

Can I use it with gas or oil appliances?

Yes, the TWPro system carries classifications for compatible gas and oil applications. Nevertheless, an installer must select the correct system classification for the appliance and operating conditions.

How far must it remain from combustible materials?

The declared distance for the relevant T600 G50 system is 50mm. However, another part of the installation may require a greater clearance.

Is a locking band required?

Yes. Fully engage the push-fit connection and secure it with the correct TWPro locking band according to the manufacturer’s instructions.

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

Do not mix chimney brands unless both manufacturers provide written approval. Different systems may use incompatible dimensions, joints and locking methods.

What is the product model?

The product model is 37-125-093.