Fernox F4 Central Heating Leak Sealer Express 400ml

By Fernox Product code: 83815 Pack size: Each

£14.98 was £19.98 Exc. VAT £12.48
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Product Details

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

Technical Specification
Brand Fernox
Manufacture ID 62422
Volume (L) 0.4
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

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

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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 Express 400ml is rated 4.6 out of 5 by 21.
Rated 5 out of 5 by from Pressure loss sorted Heating system kept loosing pressure until this was used. Not lost pressure now for several months now
Date published: 2020-07-22
Rated 5 out of 5 by from Did the trick Fixed a drip from a radiator pipe
Date published: 2020-06-11
Rated 5 out of 5 by from Easy to use Solved a problem that I have had of loss of pressure for 2 months (LOCKDOWN!)
Date published: 2020-06-08
Rated 4 out of 5 by from Fingers Crossed! I bought two of these to use in a big CH system with a probable leak causing a very damp wall. Access was impossible without major works, so I thought I would try F4. The injections into a radiator was not as efficient as with other Fernox injectors, maybe because it's a thicker, foamier consistency. I probably wasted 10% but it seems to have done the trick and the wall is drying well.
Date published: 2020-05-30
Rated 5 out of 5 by from Great product Excellent product. Easy to use. Worked first time no problems.
Date published: 2020-05-28
Rated 5 out of 5 by from Worked a treat Apprehensive at first but thought its the same company that makes the filters for my boiler so gave it a go I was losing 1.7 bar to 0 bar in less than a day had two plumbers out neither could find any leaks so used this sealer nothing happened for 48 hours then no pressure loss boiler working as it should radiators working great so to the hot water its been a few weeks now since using and everything worki g fine and no pressure loss whatsoever I have since found where the leak was due to brown stain just needed a couple of compression joints tightening but would recommend fernox leak sealer all day long
Date published: 2020-05-27
Rated 5 out of 5 by from Does what it says on the tin Great product. My Baxi boiler had a solid filling loop rather than a flexi pipe so a little more fiddling than the Fernox Video to connect up but it did the job sealing a weeping leak from a weld on our bathroom towel rail. No draining or other messing about. Much cheaper at Toolstation than others.
Date published: 2020-05-20
Rated 5 out of 5 by from Pretty easy Very easy to use with a filling loop but would be useful to have a 1/2" female connector to put on the drain valve on magnetic filters
Date published: 2020-05-01
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