Top Rated Product

Product Reviews

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

Used throughout domestic heating systems for sealing small, inaccessible leaks. Does not block air vents and pumps.
Average Customer Rating:
5 out of 5
5
 out of 
5
(7 Reviews) 7
Open Ratings Snapshot
Rating Snapshot (7 reviews)
5 stars
7
4 stars
0
3 stars
0
2 stars
0
1 star
0
7 of 7(100%)reviewers would recommend this product.
Customer Reviews for Fernox Central Heating Leak Sealer F4 500ml
Review 1 for Fernox Central Heating Leak Sealer F4 500ml
Overall Rating: 
5 out of 5
5 out of 5
Value: 
5 out of 5
5 out of 5
Features: 
5 out of 5
5 out of 5
Performance: 
5 out of 5
5 out of 5
Reliability: 
5 out of 5
5 out of 5
Would you recommend this product? Yes
Overall Rating: 
5 out of 5
5 out of 5
Value: 
5 out of 5
5 out of 5
Features: 
5 out of 5
5 out of 5
Performance: 
5 out of 5
5 out of 5
Reliability: 
5 out of 5
5 out of 5
Does Exactly What It Is Suppos
23 Jul 2013
By Boba
, Fife
"I have an oldish CH system (about 40 years old) and have been bothered for ages by a variety of hard-to-trace weeps. I recently had a new pressurised boiler fitted and the system was losing pressure at the rate of around 0.1 - 0.2 bar per week (more than 0.5 litres per week).I added the fernox and the system has lost no noticeable pressure over a period of a month. Better than expected result!"
1 of 1 people found this review helpful.
Review 2 for Fernox Central Heating Leak Sealer F4 500ml
Overall Rating: 
5 out of 5
5 out of 5
Value: 
5 out of 5
5 out of 5
Features: 
5 out of 5
5 out of 5
Performance: 
5 out of 5
5 out of 5
Reliability: 
5 out of 5
5 out of 5
Would you recommend this product? Yes
Overall Rating: 
5 out of 5
5 out of 5
Value: 
5 out of 5
5 out of 5
Features: 
5 out of 5
5 out of 5
Performance: 
5 out of 5
5 out of 5
Reliability: 
5 out of 5
5 out of 5
Does exactly what it says !
31 Jan 2013
By WirralSteve
, Wirral
"Having had a fairly bad leak from a large vertical radiator (poorly welded joints) I decided to give Fernox F4 a go by adding the whole bottle to my central heating header tank in my loft...and then draining a few pints off from one of my radiators...to get the stuff into the system & circulating. Amaizingly after only 2 hours of running the central heating...the leak had stopped completely !. Fantastic product.- does exactly what it says !."
Review 3 for Fernox Central Heating Leak Sealer F4 500ml
Overall Rating: 
5 out of 5
5 out of 5
Value: 
5 out of 5
5 out of 5
Features: 
5 out of 5
5 out of 5
Performance: 
5 out of 5
5 out of 5
Reliability: 
5 out of 5
5 out of 5
Would you recommend this product? Yes
Overall Rating: 
5 out of 5
5 out of 5
Value: 
5 out of 5
5 out of 5
Features: 
5 out of 5
5 out of 5
Performance: 
5 out of 5
5 out of 5
Reliability: 
5 out of 5
5 out of 5
it did the trick
9 Apr 2012
By perodogsbody
, Holyhead
"my central heating system had suffered from a persistent, inaccessible, weeping leak for several months. A large plumber's bill for pipework replacement was feared. A friend in the know recommended Fernox F4. Within 24 hours the leak had stopped completely. The directions for application on the container were easily followed and are spelled out slightly more specifically on the Fernox web-site. Problem solved."
1 of 1 people found this review helpful.
Review 4 for Fernox Central Heating Leak Sealer F4 500ml
Overall Rating: 
5 out of 5
5 out of 5
Value: 
5 out of 5
5 out of 5
Features: 
4 out of 5
4 out of 5
Performance: 
5 out of 5
5 out of 5
Reliability: 
4 out of 5
4 out of 5
Would you recommend this product? Yes
Overall Rating: 
5 out of 5
5 out of 5
Value: 
5 out of 5
5 out of 5
Features: 
4 out of 5
4 out of 5
Performance: 
5 out of 5
5 out of 5
Reliability: 
4 out of 5
4 out of 5
Problem solved
12 Feb 2011
By Dartman
, Gwent
"After trying and failing for almost a year to find leak causing pressure drop - and topping up every few days , I put Fernox into the system via radiator using ' no nonsence filling kit' - easily done. Since then after 3 or 4 weeks no pressure loss at all.
So far -so good I would recommend this to anyone.
"
2 of 2 people found this review helpful.
Review 5 for Fernox Central Heating Leak Sealer F4 500ml
Overall Rating: 
5 out of 5
5 out of 5
Value: 
5 out of 5
5 out of 5
Features: 
5 out of 5
5 out of 5
Performance: 
5 out of 5
5 out of 5
Reliability: 
5 out of 5
5 out of 5
Would you recommend this product? Yes
Overall Rating: 
5 out of 5
5 out of 5
Value: 
5 out of 5
5 out of 5
Features: 
5 out of 5
5 out of 5
Performance: 
5 out of 5
5 out of 5
Reliability: 
5 out of 5
5 out of 5
Does what it is supposed to do
2 Dec 2009
By redwolverton
, Milton Keynes
"Recommended by a plumber mate. Talked me through doing a partial drain down of my system and poured this in, a day or so later the leaky radiator valve has been sorted out. Does the job, what more can I say. Have patience, it didn't work straight off but 24 hours or so later and having run the central heating a couple of times seems to do the job."
2 of 2 people found this review helpful.
Review 6 for Fernox Central Heating Leak Sealer F4 500ml
Overall Rating: 
5 out of 5
5 out of 5
Value: 
5 out of 5
5 out of 5
Features: 
4 out of 5
4 out of 5
Performance: 
5 out of 5
5 out of 5
Reliability: 
5 out of 5
5 out of 5
Would you recommend this product? Yes
Overall Rating: 
5 out of 5
5 out of 5
Value: 
5 out of 5
5 out of 5
Features: 
4 out of 5
4 out of 5
Performance: 
5 out of 5
5 out of 5
Reliability: 
5 out of 5
5 out of 5
Great product
27 Nov 2009
By Sailorman
, Weston-super-Mare
"Both isolation valves on my Gloworm Combi were leaking. Expensive and difficult to replace. I was disappointed at first but after 48 hours the drips stopped. No pressure loss over 1 year later. Recommended."
2 of 2 people found this review helpful.
Review 7 for Fernox Central Heating Leak Sealer F4 500ml
Overall Rating: 
5 out of 5
5 out of 5
Value: 
5 out of 5
5 out of 5
Features: 
5 out of 5
5 out of 5
Performance: 
5 out of 5
5 out of 5
Reliability: 
5 out of 5
5 out of 5
Would you recommend this product? Yes
Overall Rating: 
5 out of 5
5 out of 5
Value: 
5 out of 5
5 out of 5
Features: 
5 out of 5
5 out of 5
Performance: 
5 out of 5
5 out of 5
Reliability: 
5 out of 5
5 out of 5
It actually Works
9 Mar 2009
By davetherave123
, London
"I had a leaking ball valve which was leaking through the open/ close screw and it was very dificult to get to to change it so i gave this stuff ago and it worked a treat."
2 of 2 people found this review helpful.