Fernox F4 Central Heating Leak Sealer 500ml

By Fernox Product code: 92490 Pack size: Each

£16.98 Exc. VAT £14.15
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Product Details

Seals small leaks and weeps which may cause pressure loss and/or boiler breakdown.


An internal leak sealer developed for use throughout a central heating system to seal small, inaccessible leaks and weeps which may cause pressure loss and boiler breakdown. Once dispersed within the system, the product finds the area of oxygen ingress and forms a polymer to seal the pinhole. Effective within 1-24 hours after application, the unique sealing efficiency of this water treatment chemical has been proven to prevent blockages or restrictions within the boiler or vulnerable system components such as pumps and safety devices. A leak can be quickly and efficiently sealed, without the need for a complete system drain down.

• Ideal for reducing pressure loss from sealed systems
• Seals most weeps and small inaccessible leaks
• Compatible with all metals and materials commonly used in central heating systems
• One 500ml recyclable bottle treats up to 130 litres of system water (16 radiators) and the equivalent of 250m2 of underfloor systems.

Technical Specification
Brand Fernox
Safety Data Sheet click here
Volume (L) 0.5
Delivery details


Covid-19 Update

  • FREE Next Business Day delivery is available for orders over £25 for orders placed before 9pm Mon-Thur and before 6pm Sunday
  • Saturday and Sunday delivery is available for orders placed before 6pm on Friday for Saturday Delivery and 4pm Saturday for Sunday delivery. Items over 30kg can only be delivered next Business Day Mon-Fri. Orders placed after 9pm Thursday will be delivered the following Monday see here for details
  • Pre-12 delivery service is now available for weekday deliveries. Place your order before 9pm Mon-Thur for next business day delivery by 12pm. Orders placed after 9pm Thur and before 6pm Sunday will be delivered by 12pm Monday. UK mainland only
  • Once your order has been dispatched you will receive an invoice email with the courier details and your tracking number
  • Alternatively go to MyAccount, click on your Order History, click on the TRACK icon to link through to the carrier website and the tracking details for your delivery
  • Delivery direct from suppliers is available and specific delivery times will be displayed on the product page
Order Value: Under £25 Over £25 but less than £75 £75 & Over
Next Business Day Mon-Fri (order by 9pm Mon-Thur & Sun by 6pm) delivered before 6pm £5 Free Free
Pre-12 Delivery Mon-Fri (order by 9pm Mon-Thur & Sun by 6pm) delivered before 12pm next day £10 £5 £5
Remote areas standard delivery (2-4 days) £5 Free Free
Saturday Delivery (order by 6pm Friday) delivered before 6pm £10 £5 Free
Sunday Delivery (order by 4pm Saturday) delivered before 6pm £10 £5 Free


Please note items delivered by our suppliers are not available for the options above. Delivery times may vary.

More about Delivery & Returns
Click & Collect details

Covid 19 Update

Click & Collect

We are fully open and delighted to welcome our customers into our branches.

Our opening times are 7am-8pm Monday-Friday, 7am-7pm Saturday and 9-4pm Sunday

Our speedy 5 min Click and Collect service remains one of the safest ways to buy from us and minimises your time in store. Place your order at toolstation.com 7 days a week, and travel to store once your collection confirmation is received by email or text message.





Don’t forget your mobile number – Please ensure that your mobile number is added so that we can text you when your order is ready to collect.

Your items will be held at your selected Toolstation branch for 14 days, after which point your order will be put back to stock and refunded automatically.

Reviews
Fernox F4 Central Heating Leak Sealer 500ml is rated 4.7 out of 5 by 60.
Rated 5 out of 5 by from Worth a try and it worked! Had a small leak in my system which required me to repressure boiler every 10-14 days. Could find no obvious leaks so assumed it must be under the concrete floors. My system had 2 zones plus hot water and 16 radiators. Put the Fernox in via towel rail and left it running with both zones open for about 8 hours. It's now 2 weeks and the boiler pressure is no longer dropping so hopefully the F4 has sealed the leak.
Date published: 2021-04-05
Rated 5 out of 5 by from Excellent product Excellent product, perfect for sealing minor leaks
Date published: 2021-04-04
Rated 5 out of 5 by from Pressure Drop On Central Heating System Had a small leak on my central heating system unfortunately all of my pipes run underneath a concrete floor, I couldn't find a leak anywhere on the pipes that I could see and the boiler had only been in a couple of years with no leaks visible, but I kept getting a pressure loss of half a bar every few days, so before I went to the expense of having to have every floor up, being as I've been in the building industry for 40+ years thought I would give Fernox F4 central heating leak sealer a go, very easy to use turn the heating off closed off the magnaflow cleaner drained it added 500ml of sealer which is just what the magnaflow holds topped up the system run the boiler for around 5 hours, so far so good no drop in pressure, definitely does what it says, well worth the price I paid from toolstation and cheaper than their competitors.
Date published: 2021-04-03
Rated 5 out of 5 by from First class Fernox D Absolutely first class product
Date published: 2021-03-22
Rated 5 out of 5 by from Radiator leak Worked an absolute treat, and so simple to use
Date published: 2021-03-22
Rated 5 out of 5 by from Fernox F4 seems to have sorted out the heating pressure drop problem, toolstation were the cheapest
Date published: 2021-03-10
Rated 5 out of 5 by from Fernox Central heating sealant Works fine and a good price
Date published: 2021-03-05
Rated 5 out of 5 by from High recommend, worked great for me. Had to top up the water pressure every couple of weeks, put this into the system and within a day am no longer losing pressure, been running around a couple months now and so far so good. I have a MagnaClean so put the leak sealer into that so didn't have to drain out the system.
Date published: 2021-03-01
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