Fernox F3 Central Heating Cleaner 500ml Product Code: 51463

Quick and effective neutral cleanser. Removes debris, sludge and scale, restoring efficiency. Non-toxic.


  • Can be Used with Powerflush Machines
  • Suitable for All Heating System Metals
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Additional Information
Technical Specification
  • Brand : Fernox
  • Product Type : Central Heating Cleaner
  • Volume : 500 ml
  • Model No : F3
  • Pack Size : 1
  • Manufacturer Guarantee : 1 Year Guarantee
  • Pieces in Pack/Case : 1
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€18.95 Incl. 20% VAT

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Fernox F3 Central Heating Cleaner 500ml is rated 4.4 out of 5 by 5.
Rated 5 out of 5 by from I wouldn't use anything else Last year I flushed my system using F3. I then refilled it and used F1. Just recently I needed to change a large radiator for a smaller one in the kitchen. Due to kitchen refurbishment nothing to do with problems with the heating system. On draining the system I was amazed to find that the water coming out of the drain tap was all but clear. So guess what I put back in? I wouldn't use anything else.
Date published: 2014-09-20
Rated 5 out of 5 by from Good System cleaner I used this after installing a number of new radiators and to clean out the remaining old radiators. New copper pipe was done as well, so this will get rid of debris and flux etc inside the pipes, as well as any muck from the manufacture of the radiators such as oils or other deposits. Seemed to do the job. After installing the radiators I repressurised the central heating with water only to check for leaks, since if there was a problem you would waste the cleaner. I then drained it and put in the cleaner to the hall way radiator and refilled and bled the system and ran it for about 3 hours. I also adjusted the valves to ensure that all radiators were cleaned, e.g all trv's are open etc. After this, it was then drained and refilled with water to ensure that it is all flushed out. Drained and then added Fernox F1 inhibitor and refilled the system etc. Should be good for a while now. I was recommended to use Fernox inhibitor with my boiler, so I do and this is a suitable cleaner for use with my new combi boiler. If I need to, I will be using it again in the future, but it would either be many years because the inhibitor is very good, or if I need to solder more pipes then I would use the cleaner to clean then out again. This is highly recommended.
Date published: 2014-09-14
Rated 4 out of 5 by from good cleaner Does what it says on the plastic bottle used it for years
Date published: 2014-06-07
Rated 4 out of 5 by from Fernox F3 cleaner Used F3 in a domestic heating system that hadn't been cleaned for 5 years or more and it seems to have done a great job. The boiler is quieter and better behaved now than before the cleaning, and it seems to have shifted quite a lot of material from the radiators.
Date published: 2014-06-06
Rated 4 out of 5 by from Works well (probably!). Wrongly titled here, since Fernox F5 is the "heavy duty" version. F3 is the gentle cleaner. I've used both. It is neutral, as in non-acidic, making it good if you don't want to expose any hidden leaks in the system. The F3 has cleared most of the magnetite (black rust) that was clogging my heating, without the use of a power-flushing machine. It's hard to give a definitive review, as my situation is unusual: My heating is a 51 year old overhead gravity system with iron pipes, not cleaned for decades, and I'm doing repeat cleans with F3 and F5. Curiously, the heating works 100% while the F3 is in the system (not so with F5), but it has to be removed/flushed after 7 days max. But this cleaner appears to do its job. Good value here at Screwfix.
Date published: 2009-10-25
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