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Fernox F4 Central Heating Leak Sealer 500ml (45902)

Used throughout domestic heating systems for sealing small, inaccessible leaks. Does not block air vents and pumps.

  • 1 Year Guarantee

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£16.99INC VAT (£33.98/Ltr)

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Fernox F4 Central Heating Leak Sealer 500ml is rated 4.4 out of 5 by 20.
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Rated 1 out of 5 by from Boiler Presure Droping Had a leak in heating system thought this would be ideal way to fix it, 5 radiator 1 t/rail 24hrs later, still leaking USELESS STUFF and its not the cheapest Did not work on the last leak either
Date published: 2016-11-20
Rated 5 out of 5 by from saved from a mighty mess. Having developed a leak on some underground skimmer swimming pool pipework and not keen on digging up tiles/floor/ground for 50 metres to find it decided to give this a try.blocked the pipe return at the pool and dumped it into the other end,filled with water and crossed fingers,where was losing 80mm a day in height,now dropped that to under 10...happy days only 4 stars for reliability as its only been 2 weeks but heres hoping
Date published: 2016-11-19
Rated 5 out of 5 by from Miracle Cure Had a tiny leak on a 10mm Microbore joint to a Towel Rad in the Downstairs toilet,losing @ half a cup per day. Didn't really want to be draining full system down etc at this time of year. Read reviews on this product which @95% seemed positive. I have 22 Rads so needed 2 Bottles which did seem dear but worth a try. Very easy to use, drained @ 2 litres from Kitchen Rad via drain off , and then poured contents of both bottles into Bathroom Towel Rad. Because its quite thick didn't need funnel, poured straight in.. Cautiously switched Heating on for 15 mins & worked immediately. I keep checking everyday , been a week now and still bone dry. Don't know how it works but it does , well worth giving it a try.
Date published: 2016-11-18
Rated 4 out of 5 by from Good as always but............ This is the second time I have used this product. 1st two years ago and worked perfectly. The problem of loosing pressure from my combi boiler has now reappeared now winter is here. I have used two 500ml this time and so far so good and await to see if it works long term. if you have a leak that's big the inevitable will be a full repair, F4 can not work wonders!
Date published: 2016-11-10
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How long should the system be run after you add the fernox F4

Asked by: Walshy5050
Hello Walshy5050. We recommend that you run the system for around half an hour to circulate the F4, however once this is done it should be left for a week to set. Hope this helps.
Answered by: Fernox Client Services
Date published: 2017-08-02

Leak cure

Hi, How long will it fix the leak for? also would you recommend flushing it out of the system after a month and it becomes deactivate? Thanks
Asked by: Gbroughall
Hello Gbroughall. Unfortunately this would depend on a lot of different factors, so would be impossible to say without looking at the system and leak itself. It is possible that it can fix the leak permanently, however I cannot guarantee that it will. You do not need to flush out the system after using Leak Sealer F4. Hope this helps.
Answered by: Fernox Client Services
Date published: 2017-08-03

Lifespan

Hi, What is the normal life span of this in a system?
Asked by: Gbroughall
Hello Gbroughall, the F4 Central Heating Leak Sealer stay active in a system for a month.
Answered by: Fernox Client Services
Date published: 2017-06-23

How many bottles will I need?

I have 2 Towel radiators, 1 double radiator, 1 single radiator, 1 tower radiator and 2 single bay window radiators in a 2-bed semi-detached. 7 radiators in total. Thanks
Asked by: chrisne
Hello Chrisne. One bottle of F4 Central heating Leak Sealer will be sufficent to dose a system of this sixe. Hope this helps.
Answered by: Fernox Client Services
Date published: 2017-07-08

Can I use to much I've got 6 twin rads and 3 single rads do i need 1or 2 bottles

Asked by: Dikk
Hi Dikk, you need 2 bottles to treat your system
Answered by: Fernox Client Services
Date published: 2017-04-26
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Specification
Brand Fernox
Manufacturer Guarantee 1 Year Guarantee
Model No F4
Pack Size 1
Pieces in Pack/Case 1
Product Type Central Heating Leak Sealer
Volume 500 ml

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Safety Data Sheet (COSHH)