DM36 - 350mm square x 250mm high casing & soot door
At a Glance
- Double wall insulation system
- Durable, heat-retaining pumice construction
- Quick & straightforward installation
- Maintains optimum flue gas temperatures
- Reduces risk of heat transfer and thermal stress
- Suitable for diverse heating appliances

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: sales@nationalflues.com
- Info
- Specs
- Install
- FAQs
The DM36 350mm square x 250mm high casing & soot door is a top-tier product in our Isokern DM block system range. This double wall system expertly maintains flue gas temperatures while ensuring that heat is not transferred to the outer casing, making it safe and efficient. The innovative design separates the inner and outer components, accommodating thermal movement to reduce the risk of cracking, leaks, or stains.
Its installation is both quick and straightforward, making it a top choice for professionals and DIY enthusiasts alike. Available in three outer casing sizes - DM36, DM44, and DM54, it is suitable for a wide range of applications including stoves, open fires, inserts, and cookers that burn wood, solid fuel, oil, or gas. However, it is not recommended for condensing appliances such as Biomass and Pellets.
Crafted from pumice, a natural insulator, this casing ensures that your heating appliance rapidly reaches optimal performance and maintains temperature efficiently. Isokern DM is both HETAS Approved and CE marked, offering you peace of mind in terms of safety and regulatory compliance. For optimal results, always refer to the installation guides provided.
SKU: 59-130713
Delivery Information +
We work relentlessly to ensure you get your order fast. Estimated delivery for this product is Monday, April 7th. 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.
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National Flues Ltd Verdict
The DM36 - 350mm square x 250mm high casing & soot door impresses with its superior insulation and easy installation. Perfect for a range of heating appliances, it's a solid choice for both retail and trade customers. Enjoy reliable nationwide delivery with National Flues!
The DM36 casing & soot door is designed for use with various heating systems to efficiently maintain and manage flue gas temperatures, ensuring optimal performance and safety.
National Flues provides top-quality fireplaces and flue systems to both retail and trade customers across the UK. Known for competitive pricing, reliable delivery, and excellent customer service, they are an industry leader.
