---
product_id: 392084577
title: "CW4 Central Heating Leak Sealer – for Up to 18 Single Radiators – Leak Seal & Stop – Radiator & Boiler Leak Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss in Hydronic Heating"
brand: "coswarm"
price: "€ 121.83"
currency: EUR
in_stock: true
reviews_count: 5
category: "Cos Warm"
url: https://www.desertcart.sk/products/392084577-cw4-central-heating-leak-sealer-for-up-to-18-single
store_origin: SK
region: Slovakia
---

# Biodegradable & eco-safe Seals leaks up to 18 radiators Compatible with all metals CW4 Central Heating Leak Sealer – for Up to 18 Single Radiators – Leak Seal & Stop – Radiator & Boiler Leak Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss in Hydronic Heating

**Brand:** coswarm
**Price:** € 121.83
**Availability:** ✅ In Stock

## Summary

> 💧 Seal the leaks, save the heat, skip the hassle!

## Quick Answers

- **What is this?** CW4 Central Heating Leak Sealer – for Up to 18 Single Radiators – Leak Seal & Stop – Radiator & Boiler Leak Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss in Hydronic Heating by coswarm
- **How much does it cost?** € 121.83 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.sk](https://www.desertcart.sk/products/392084577-cw4-central-heating-leak-sealer-for-up-to-18-single)

## 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-Conscious Heating:** Biodegradable, non-toxic formula protects your home and the planet
- • **Effortless & Permanent:** Just pour in—no draining or repairs needed, stays in system permanently
- • **Metal-Friendly Formula:** Safe for steel, copper, aluminum & all common heating metals
- • **Leak-Proof Your Comfort:** Stops minor leaks & pressure loss without system shutdown
- • **Power-Packed Concentrate:** One 500ml bottle treats up to 150L heating systems (18 radiators)

## Overview

CW4 Central Heating Leak Sealer is a super concentrated, biodegradable solution designed to seal minor leaks and fix pressure loss in hydronic heating systems up to 18 radiators. Compatible with all metals, it works without shutting down your boiler, saving time and repair costs while maintaining system efficiency.

## Description

Stop Boiler Leaks & Fix Pressure Loss With CW4 Leak SealerOne of the most common problems with the boiler and central heating system is pressure loss. Most of the time, this caused by tiny leaks due to rust and corrosion, a broken seal, faulty water pipe connections, or a damaged valve or pump. It is not feasible to shut down the whole system just because of a small leak because it can take a toll on your time and money. For fixing small leaks, CW4 Leak Sealer is the perfect option.How Does CW4 Leak Sealer Help?Seals most minor leaks, weeps and drips that do not need immediate repairCan fix even the most inaccessible leaks and weeping jointsReduces pressure loss caused by minor leaks from the sealed systemsFor long-lasting repairSaves time and money by not closing the system and repairing the boilersSaves you from the stress of finding a repair companyMaintains boiler efficiencyFeatures:Does not interfere with the operation of the system so no need for complete boiler shutdownsDoes not clog or cause blockages in pumps, controls, vents, or valves.Compatible with all metals and materials commonly used in the system like aluminum, ferrous metals, copper, copper alloys, mild steel and stainless steel.Biodegradable formula can be used worry free around people, the environment and boilers500ml is sufficient for treating a typical domestic central heating system of up to 18 radiators.How Does It Work?CW4 Leak Sealer mixes instantly with water and travels to small leaks and forms a soft seal by changing the surface tension of water. The unique sealing efficiency of our proven formula is perfect for keeping the seal intact and stopping any further leaks. Works best for capillary leaks.Want to fix that minor leaks in your central heating system? Click on the “Add To Cart” button now and watch how efficiently CosWarm CW4 seals the leaks.

Review: Excellent produit Ça a fonctionné du premier coup Pour un trou dans un radiateur en acier Super je recommande
Review: Mijn vloerverwarming had een lekkage, wist niet of dit ook geschikt was voor vloerverwarmingsslangen maar daar lijkt het wel op. Na dit middel te hebben toegevoegd hebben wij geen drukverlies meer. He wel voor de zekerheid de slangen goed doorgespoeld met schoon water voordat ik het erin deed.

## Features

- 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 sealer can be used for up to 18 single radiators i.e., a 150-liter system. It is easy to use, just pour it in the system according to the instructions and let it work.
- SUITABLE TO USE AROUND METALS: There are many leak sealer 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 aluminum.
- 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.
- BIODEGRADABLE: Our leak sealer is a safer alternative compared to other 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 |
| ASIN  | B088JYB6JZ |
| Batteries Included? | No |
| Batteries Required? | No |
| Customer Reviews | 4.1 4.1 out of 5 stars (521) |
| Customer reviews | 4.1 4.1 out of 5 stars (521) |
| Date First Available | 10 January 2021 |
| Date First Available  | 10 January 2021 |
| Item Weight | 453 g |
| Manufacturer | CosWarm |
| Manufacturer  | CosWarm |
| Manufacturer reference | CosWarmCW4 |
| Manufacturer reference  | CosWarmCW4 |
| Package Dimensions | 18.2 x 8.6 x 5.8 cm; 453.59 g |
| Package Dimensions  | 18.2 x 8.6 x 5.8 cm; 453.59 g |
| Part number | CosWarmCW4 |
| Size | 500 ml |

## Images

![CW4 Central Heating Leak Sealer – for Up to 18 Single Radiators – Leak Seal & Stop – Radiator & Boiler Leak Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss in Hydronic Heating - Image 1](https://m.media-amazon.com/images/I/714vUY2aybL.jpg)
![CW4 Central Heating Leak Sealer – for Up to 18 Single Radiators – Leak Seal & Stop – Radiator & Boiler Leak Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss in Hydronic Heating - Image 2](https://m.media-amazon.com/images/I/71JaROVtP2L.jpg)
![CW4 Central Heating Leak Sealer – for Up to 18 Single Radiators – Leak Seal & Stop – Radiator & Boiler Leak Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss in Hydronic Heating - Image 3](https://m.media-amazon.com/images/I/71XKkZD0JVL.jpg)
![CW4 Central Heating Leak Sealer – for Up to 18 Single Radiators – Leak Seal & Stop – Radiator & Boiler Leak Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss in Hydronic Heating - Image 4](https://m.media-amazon.com/images/I/71Y+v30uucL.jpg)
![CW4 Central Heating Leak Sealer – for Up to 18 Single Radiators – Leak Seal & Stop – Radiator & Boiler Leak Sealant - Stops Minor Leaks & Weeps, Fixes Pressure Loss in Hydronic Heating - Image 5](https://m.media-amazon.com/images/I/71mUA7Jg4VL.jpg)

## Customer Reviews

### ⭐⭐⭐⭐⭐ Review
*by V***E on 9 January 2026*

Excellent produit Ça a fonctionné du premier coup Pour un trou dans un radiateur en acier Super je recommande

### ⭐⭐⭐⭐⭐ Review
*by T***O on 10 July 2024*

Mijn vloerverwarming had een lekkage, wist niet of dit ook geschikt was voor vloerverwarmingsslangen maar daar lijkt het wel op. Na dit middel te hebben toegevoegd hebben wij geen drukverlies meer. He wel voor de zekerheid de slangen goed doorgespoeld met schoon water voordat ik het erin deed.

### ⭐⭐⭐⭐⭐ Review
*by M***A on 17 January 2026*

Un prodotto eccellente per riparare micro-perdite e stabilizzare la pressione degli impianti di riscaldamento. La formula concentrata tratta fino a 18 radiatori ed è compatibile con tutti i metalli, alluminio incluso. Soluzione professionale, sicura e facile da gestire. Consigliatissimo per la manutenzione.

## 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

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**Shop now:** [https://www.desertcart.sk/products/392084577-cw4-central-heating-leak-sealer-for-up-to-18-single](https://www.desertcart.sk/products/392084577-cw4-central-heating-leak-sealer-for-up-to-18-single)

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*Product available on Desertcart Slovakia*
*Store origin: SK*
*Last updated: 2026-03-19*