Fernox F4 Central Heating Leak Sealer 500ml (766PP)

£ 18.59INC VAT

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Fernox F4 Central Heating Leak Sealer 500ml (766PP)

Internal leak sealer developed for use throughout a central heating system to seal microscopic, inaccessible leaks and weeps which may cause pressure loss and boiler breakdown. Saves time and money on draining down the system and repair costs. Does not cause blockages in pipework or vulnerable boiler components such as pumps, air vents and heat exchangers. Compatible with all metals and materials, including aluminium. Designed to be left permanently in the system. One bottle treats a 130Ltr system, up to 16 radiators, or 250m² of underfloor heating.

  • 1 Year Guarantee
  • Fixes System Pressure Loss Quickly
  • Concentrated Fast-Acting Formula

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View all: Fernox Central Heating Leak Sealers

£18.59INC VAT (£37.18/Ltr)

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Rated 5 out of 5 by from Fernox F4 Combi boiler slowly losing pressure. No leaks found on the system, boiler or overflow/outlet. A bottle of F4 was tried before calling a boiler technician in to look at it. Boiler now holding a steady pressure.
Date published: 2022-01-06
Rated 5 out of 5 by from Hoping for a quick fix My boiler was losing pressure slowly, checked all the obvious locations on the radiators and boiler. Presumed there must be a crack in a pipe under the flooring. Thought I would give this stuff a try, easy to use, took about 10 minutes to get the liquid into the sealed system. Can’t confirm it has works as will take a few days to travel around the heating system. Ease of use gives it 5 stars alone.
Date published: 2022-01-01
Rated 5 out of 5 by from Does the job extremely well Had a leak from back of combi boiler and despite spending a couple of hours trying to find it I still couldn't find where it was coming from. Constant drip, drip, drip and lost about 4 litres of water overnight. Poured Fernox f4 into the filter and within an hour the leak had stopped. Boiler pressure up to normal and hasn't lost any since. Highly recommended
Date published: 2021-12-19
Rated 5 out of 5 by from Micro leak Seems to have fixed a micro leak on a new towel rail but on another older rad tail drips and did not work but I suspect I need a new rad as I've tried every product and method to fix,so for small leaks works well.
Date published: 2021-12-02
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Can this be used in a vented system?

Asked by: Chachobonswalez
Hi, Yes the only place it cannot be used is in a Primatic system. It does however need access to air to work so if the leak is in pipework that is lagged or buried in solid concrete channels it will not work
Answered by: Fernox Client Services
Date published: 2022-04-01

Can this be used to seal a leak in one of the pipes that are behind a wall? If so how do I get this into the system?

Asked by: Chrissythemoo
Hi Chrissythemoo, Yes Leak sealer F4 is designed to fix the leaks that you cannot get at. Use Fernox F4 Express, exactly the same product just a different means of getting it into the system, it is a pressurised can that can be injected into the system via a radiator, boiler filling loop or Fernox TF1 Filter. Dose rate is 1 can for every 130 litres of water or 16 single panelled radiators.
Answered by: Fernox Client Services
Date published: 2022-02-09

Boiler leaks

Can this product be used for very small leaks from the boiler itself eg where there is evidence of liquid evaporation.
Asked by: YorkshireScrewdriver
Hi, Possibly but it may be too hot for it. If you can see where the actual leak is use Fernox LS-X, blot contact surface dry first.
Answered by: Fernox Client Services
Date published: 2021-12-18
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Specification
Brand Fernox
Label Info 3: Precautionary Statements P101 If medical advice is needed, have product container or label at hand.P102 Keep out of reach of children.P103 Read label before use.
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

Downloads

Safety Data Sheet (COSHH)