TWPro MB - Twin Wall to Twin Wall Increaser - Ø 125-150mm
At a Glance
- Compatible with solid fuel and gas/oil appliances
- Robust construction with dual stainless steel layers
- High temperature black coated outer skin
- Compressed rockwool insulation (200kg/m3) for efficient heat retention
- HETAS approved and CE marked for safety
- Maintains a safe 50mm clearance from combustibles

Please Note: All dimensions refer to the internal diameter of flues. If unsure, please call 01670 206999 to ensure you choose the correct products.
We Won't Be Beaten On Price
At National Flues, we continuously monitor competitor prices. This ensures that we consistently offer you the best deals on all our products. Here’s how we keep your costs low:
- Daily Price Matching: Our team adjusts prices to ensure we stay competitive.
- Bulk Purchasing Power: We sell a lot, so we can negotiate better rates with suppliers, passing the savings directly to you.
- Operational Efficiency: We have streamlined processes to reduce overhead.
Price Match Guarantee: If you find the same product cheaper within 48 hours, we’ll match it and refund the difference.
Free Delivery Over £100: Orders over £100 are free delivery (call us if delivery is required outside the mainland UK).
“I saved 20% on my purchase compared to other retailers. Exceptional service!” – Jane D.
Have Questions?
Phone: 01670 206999
Email: [email protected]
- Info
- Specs
- Install
- FAQs
The TWPro MB - Twin Wall to Twin Wall Increaser (Ø 125-150mm) is a versatile component designed for solid fuel and gas/oil appliances including woodstoves, gas coal effect fires, oil boilers, and gas boilers. Constructed with an outer skin of 304 stainless steel and an inner skin of 316 stainless steel, both 0.4mm thick, this increaser guarantees durability and superior performance. The high temperature black finish on the outer skin not only enhances its aesthetic appeal but also provides robust protection against heat.
The insulation is made of compressed rockwool with a density of 200kg/m3, ensuring efficient heat retention. Fully welded for robustness, this increaser mandates a safe distance of 50mm from combustible materials such as wood and plasterboard. Proudly carrying HETAS approval and CE marking, it adheres to EN1856-1 T600 N1 W V2 L50040 G50 and EN1856-1 T200 P1 W V2 L50040 O20 standards.
Installation is straightforward, requiring the use of a Locking Band to secure the parts together, ensuring a hassle-free setup.
SKU: 37-125-004
Technical Specifications | |
---|---|
SKU | 37-125-004 |
Size | 125mm to 150mm |
Inner Material | 316L Stainless Steel - 0.40mm thick |
Outer Material | 304 Stainless Steel - 0.40mm thick with high temperature black coating |
Insulation | Compressed Rockwool (200kg/m3) |
Approvals | HETAS / CE |
Clearance | 50mm from combustible materials |
Designation | EN1856-1 T600 N1 W V2 L50040 G50 / EN1856-1 T200 P1 W V2 L50040 O20 |
System | TWPro Black |
Applications | Woodstoves, gas coal effect fires, oil boilers, gas boilers |
Delivery Information +
We work relentlessly to ensure you get your order fast. Estimated delivery for this product is Thursday, April 3rd. If you need faster stove or fireplace delivery please give us a call. We can often reduce longer lead times if we pay the carrier £25 for express delivery. Visit our Shipping Information page for more information.
Warranty & Returns +
All our products come with warranties. Mi-Flex offers a lifetime guarantee. Returns for damaged items are covered by insurance; non-damaged returns incur return delivery costs.
Price Match Guarantee +
We will match any price like for like. If you find it cheaper within 48 hours, we'll refund the difference.
Compatible and other products that may be of interest...
National Flues Ltd Verdict
At National Flues, we pride ourselves on supplying top-notch fireplace and flue components like the TWPro MB Increaser. It’s HETAS approved, highly reliable, and offers great value for money. Plus, you can count on our nationwide delivery service, catering to both retail and trade customers.
The TWPro MB - Twin Wall to Twin Wall Increaser is designed to increase the diameter of your flue system from 125mm to 150mm, catering to various solid fuel and gas/oil appliances, enhancing flue performance and ensuring safe operation.
National Flues is a leading UK supplier of fireplaces and flues, offering reliable products at competitive prices with dependable delivery services for both retail and trade customers.
