--- product_id: 207930694 title: "CW4 Central Heating Leak Sealer - Treats Up to 18 Radiators - Stops Leak - Boiler Leak Repair & Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss & Leaking Pipes - Underfloor Heating" brand: "coswarm" price: "12.51 DT" currency: TND in_stock: false reviews_count: 13 url: https://www.desertcart.tn/products/207930694-cw4-central-heating-leak-sealer-treats-up-to-18-radiators store_origin: TN region: Tunisia --- # Non-toxic & biodegradable Treats up to 18 radiators Stops minor leaks & pressure loss CW4 Central Heating Leak Sealer - Treats Up to 18 Radiators - Stops Leak - Boiler Leak Repair & Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss & Leaking Pipes - Underfloor Heating **Brand:** coswarm **Price:** 12.51 DT **Availability:** ❌ Out of Stock ## Summary > 🔥 Seal leaks, save time, and stay warm—effortless heating peace of mind! ## Quick Answers - **What is this?** CW4 Central Heating Leak Sealer - Treats Up to 18 Radiators - Stops Leak - Boiler Leak Repair & Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss & Leaking Pipes - Underfloor Heating by coswarm - **How much does it cost?** 12.51 DT with free shipping - **Is it available?** Currently out of stock - **Where can I buy it?** [www.desertcart.tn](https://www.desertcart.tn/products/207930694-cw4-central-heating-leak-sealer-treats-up-to-18-radiators) ## Best For - coswarm enthusiasts ## Why This Product - Trusted coswarm brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Eco & User Safe:** Non-toxic, biodegradable formula that protects your home and the planet. - • **Pressure Perfected:** Stops leaks and fixes pressure loss to keep your heating running efficiently all winter long. - • **Effortless Leak Repair:** Simply pour in without shutting down your heating system—fix leaks while staying cozy. - • **Metal-Friendly Formula:** Safe for all metals including steel, copper, aluminum—no corrosion, no damage. - • **Super Concentrated Power:** One 500ml bottle treats a full 150-litre system—up to 18 radiators, saving costly repairs. ## Overview CW4 Central Heating Leak Sealer is a super concentrated, non-toxic formula designed to seal minor leaks and fix pressure loss in central heating systems. Treating up to 18 radiators (150 litres), it works without system shutdown and is safe for all metals and the environment, offering a hassle-free, eco-friendly solution to common boiler leaks. ## Description Free delivery and returns on all eligible orders. Shop CosWarm CW4 Central Heating Leak Sealer - Treats Up to 18 Radiators - Stops Leak - Boiler Leak Repair & Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss & Leaking Pipes - Underfloor Heating. Review: Did the job! - We had a very small leak on a radiator valve and bought this to see if it would stop the leak rather than draining the system and replacing the valve. It worked a treat and no more leak. Review: Works well - Kept losing boiler pressure due to small leak under floor. A few days after treatment the pressure is fine. ## Features - Contains 1,2-benzisothiazol-3(2H)-one. May produce an allergic reaction. - Safety data sheet available on request. - STOPS SMALL LEAKS & FIXES PRESSURE LOSS: CW4 Leak Sealer seals all the small and inaccessible leaks, thus saving time and money in draining down and repairing cost. Our boiler leak sealant also helps in fixing pressure loss due to minor leaks from central heating systems. - SUPER CONCENTRATED FORMULA: Our boiler and central heating system leak stopper can treat up to 18 single radiators, i.e., a 150-litre system. It is easy to use, just pour it in the system according to the instructions and let it work. - HARMLESS FOR METALS: There are many leak sealant chemicals that are not friendly when they come into contact with metals. CW4 Leak Sealer liquid is suitable for use with all the metals and materials, including steel, ferrous metals, copper and aluminium. - CONVENIENCE AT ITS BEST: Our leak sealer and stopper makes minor repairs in the boiler a breeze. It does not interfere with the working of your central heating systems and you won’t have to shut down the systems before or while using it. The product can be left in the system permanently. - SAFE FOR YOU, THE BOILERS & THE ENVIRONMENT: Our non-toxic radiator leak sealer is a safer alternative compared to other toxic, chemical formulas. As it is biodegradable, it won’t harm Mother Nature either. Safe to use around people, the environment and your heating systems. ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B088JYB6JZ | | Batteries Required? | No | | Batteries included? | No | | Best Sellers Rank | 326,032 in DIY & Tools ( See Top 100 in DIY & Tools ) 3,167 in Sealers | | Customer Reviews | 4.0 4.0 out of 5 stars (531) | | Date First Available | 12 May 2020 | | Item Weight | 453 g | | Manufacturer | CosWarm | | Manufacturer reference | CosWarmCW4 | | Package Dimensions | 18.2 x 8.6 x 5.8 cm; 453.59 g | | Part Number | CosWarmCW4 | | Size | 500ml | ## Images ![CW4 Central Heating Leak Sealer - Treats Up to 18 Radiators - Stops Leak - Boiler Leak Repair & Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss & Leaking Pipes - Underfloor Heating - Image 1](https://m.media-amazon.com/images/I/71zDWDxQPuL.jpg) ![CW4 Central Heating Leak Sealer - Treats Up to 18 Radiators - Stops Leak - Boiler Leak Repair & Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss & Leaking Pipes - Underfloor Heating - Image 2](https://m.media-amazon.com/images/I/71ywcVM2L4L.jpg) ![CW4 Central Heating Leak Sealer - Treats Up to 18 Radiators - Stops Leak - Boiler Leak Repair & Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss & Leaking Pipes - Underfloor Heating - Image 3](https://m.media-amazon.com/images/I/71JaROVtP2L.jpg) ![CW4 Central Heating Leak Sealer - Treats Up to 18 Radiators - Stops Leak - Boiler Leak Repair & Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss & Leaking Pipes - Underfloor Heating - Image 4](https://m.media-amazon.com/images/I/71mUA7Jg4VL.jpg) ![CW4 Central Heating Leak Sealer - Treats Up to 18 Radiators - Stops Leak - Boiler Leak Repair & Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss & Leaking Pipes - Underfloor Heating - Image 5](https://m.media-amazon.com/images/I/714vUY2aybL.jpg) ## Customer Reviews ### ⭐⭐⭐⭐⭐ Did the job! *by R***M on 5 April 2022* We had a very small leak on a radiator valve and bought this to see if it would stop the leak rather than draining the system and replacing the valve. It worked a treat and no more leak. ### ⭐⭐⭐⭐⭐ Works well *by K***. on 22 December 2021* Kept losing boiler pressure due to small leak under floor. A few days after treatment the pressure is fine. ### ⭐⭐⭐⭐ OK for small pressure loss,but sadly no help for me. *by A***R on 20 March 2023* Leak on garage radiator tap. ## Frequently Bought Together - CosWarm CW4 Central Heating Leak Sealer - Treats Up to 18 Radiators - Stops Leak - Boiler Leak Repair & Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss & Leaking Pipes - Underfloor Heating - QuickFill - SEL9260: Central Heating Dosing Tool - Add Chemicals Like Fernox Central Heating Inhibitor, Sludge Remover, Leak Sealer & Sentinel X100 to Your Central Heating System --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.tn/products/207930694-cw4-central-heating-leak-sealer-treats-up-to-18-radiators](https://www.desertcart.tn/products/207930694-cw4-central-heating-leak-sealer-treats-up-to-18-radiators) --- *Product available on Desertcart Tunisia* *Store origin: TN* *Last updated: 2026-09-09*