Skip to product information
1 of 4

Fernox

Fernox Central Heating Leak Sealer F4 Express

Fernox Central Heating Leak Sealer F4 Express

SKU:374825

Regular price €43,95 EUR
Regular price Sale price €43,95 EUR
Sale Sold out
Tax included. Shipping calculated at checkout.

In stock

Shipping

🚚 Delivery Information

We offer reliable delivery across the UK using trusted national couriers.

All delivery times are estimates and begin once your order has been dispatched. Orders are dispatched from the UK.

✅ Free UK Mainland Delivery

Free delivery is available on orders over £100 within the UK mainland, excluding certain large, heavy, or fragile items.

Free delivery does not apply to:

  • Oversized items (over 1m in length)
  • Heavy items (including aggregates, compost, and logs)
  • Fragile items (such as ceramics and shower enclosures)

These items may incur a delivery charge due to specialist handling requirements.

🇬🇧 Standard Delivery – UK Mainland

(Excludes Northern Ireland)

Estimated delivery: 7–10 working days

Item WeightCostUnder 1kg£4 (Free over £100)1–10kg£7 (Free over £100)10–30kg£15 (Free over £350)30kg+ (Bulky)£35 (Minimum order £100)

🌍 Northern Ireland, Scottish Highlands & Islands

Estimated delivery: 7–10 working days

Item WeightCostUnder 1kg£71–10kg£1510–30kg£2530kg+ (Bulky)£35 (Minimum order £100)

📦 Additional Information

  • Delivery costs are calculated at checkout
  • Orders are shipped using trusted UK couriers
  • Tracking information is provided once your order is dispatched
  • Delivery times may vary during peak periods

If you have any questions about delivery, please contact us before placing your order.

❓ Frequently Asked Questions

Q: Can I choose a delivery date?
A: At present, we are unable to offer timed or date-specific delivery.

Q: What happens if my item arrives damaged?
A: Please contact us within 48 hours of delivery and we’ll resolve the issue promptly.

Returns

View full details

Fernox Central Heating Leak Sealer F4 Express – 400ml

The Fernox Central Heating Leak Sealer F4 Express is a highly effective and convenient solution for sealing minor leaks and weeps in central heating systems. Designed for ease of use, this leak sealer can be quickly administered without creating mess or requiring complex procedures. It works efficiently to detect and seal small leaks, preventing costly repairs and ensuring optimal system performance.

With its environmentally friendly formulation, the Fernox F4 Express is non-toxic and safe for use in domestic and commercial heating systems. The product is fully compatible with all Fernox Protectors, ensuring seamless integration into your existing maintenance routine.


Key Features

  • Quick & Convenient Application
    • Doses into the system in just 30 seconds, saving time and effort.
  • Mess-Free & Simple to Use
    • Can be applied easily via a radiator adapter or filling loop (supplied).
  • Advanced Leak-Sealing Formula
    • Seeks out and seals most minor weeps and leaks in the system.
  • Prevents Costly Repairs
    • Avoids the need for draining down the system or carrying out expensive repairs.
  • Safe & Environmentally Friendly
    • Non-toxic formulation, making it safe for both users and the environment.
  • Compatible with All Fernox Protectors
    • Works seamlessly with other Fernox products for enhanced system protection.
  • Pump & Vent Safe
    • Does not cause blockages in pumps, air vents, or other components of the system.
  • 100% Recyclable Can
    • Environmentally responsible packaging for sustainable usage.

Specifications

Attribute Details
Product Name Fernox Central Heating Leak Sealer F4 Express
Volume 400ml
Boxed Weight 300g
Application Method Radiator adapter or filling loop (supplied)
Country of Origin Great Britain
Compatibility Suitable for use with all Fernox Protectors
Safety Non-toxic, does not block pumps or vents
Packaging 100% recyclable

Benefits

  • Reduces Downtime & Disruptions – No need to drain the system for minor leak repairs.
  • Saves Money – Prevents expensive call-outs and repairs.
  • Extends System Lifespan – Helps maintain system integrity by preventing leaks from worsening.
  • Eco-Friendly Choice – Safe, non-toxic formula with recyclable packaging.
  • Quick & Efficient Fix – Seals leaks rapidly, reducing heat loss and improving energy efficiency.

Frequently Asked Questions (FAQs)

1. How long does it take for Fernox F4 Express to work?

  • The product begins sealing leaks immediately upon circulation, with full effectiveness typically achieved within 24 hours.

2. Is Fernox F4 Express safe to use in all central heating systems?

  • Yes, it is compatible with all Fernox Protectors and is safe for use in domestic and commercial systems.

3. Will this product block my pump or air vents?

  • No, the formula is specifically designed not to cause blockages in pumps, vents, or other essential system components.

4. Do I need to drain my system before using this leak sealer?

  • No, one of the key benefits of Fernox F4 Express is that it can be added without draining the system, making it a convenient and cost-effective solution.

5. How is the product applied?

  • The leak sealer can be added via a radiator adapter or filling loop, both of which are supplied with the product.

6. Is Fernox F4 Express environmentally friendly?

  • Yes, the formulation is non-toxic, and the packaging is 100% recyclable, making it an eco-conscious choice.

7. How much of the product should I use for my system?

  • A 400ml can is sufficient for treating a typical domestic heating system (up to 130 liters or approximately 12 radiators).

Warranty Information

Fernox provides a manufacturer’s warranty ensuring the quality and performance of the Central Heating Leak Sealer F4 Express. If you experience any issues related to manufacturing defects, you may be eligible for a replacement or refund, subject to the terms and conditions outlined by Fernox. For further warranty details, refer to the packaging or contact the manufacturer directly.


Conclusion

The Fernox Central Heating Leak Sealer F4 Express – 400ml is an essential maintenance solution for preventing and repairing minor leaks in central heating systems. Its fast-acting, easy-to-use, and eco-friendly formulation makes it a top choice for homeowners and professionals alike. By eliminating the need for draining and reducing repair costs, this product offers a cost-effective and reliable way to keep your heating system running efficiently.