03330 112 112
Cookie Reports - Screwfix Cookie Policy

Fernox

Fernox Central Heating Leak Sealer F4 500ml

Product Code: 45902

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

View more information

Download more information...

Safety Data Sheet (COSHH)

£16.99

INC.
VAT

(£33.98/Ltr)

Add to saved list


Available for deliveryNext Day Delivery
Available for collection from store Store Collection Check stock in your store
Page 1 of 4
Page 1 of 4
Rated 5 out of 5 by Brilliant Didn't think this would work or be easy to use, it was both, sealed my leaks, my combi boiler has now started holding pressure - don't think it's ever done that! 14 Jan 2016
Rated 5 out of 5 by Does what it says ion the tin As a retired plumber with a back injury, i was not too keen to have to drain down my combo boiler system. I had developed 3 leaks and was encountering pressure drops. One from an iso valve gland, one from a lock shield valve and one from the boiler heating feed pipe. I had never used F4 sealer before, and was a little reluctant. I isolated my bathroom towel rail, and removed the top bleed point fitting. I then used a hand siphon to remove just over half a litre of water. I then added the F4 and topped the towel rad back up to the brim. Bleed plug back in and valves re-opened. Less than 5 minutes to complete......DID it work ? Yep, i was well impressed no sign of a leak anywhere after a couple of weeks and pressure is maintained. Recommended. 2 Jan 2016
Rated 2 out of 5 by Unable to sort leak The boiler engineer has put my boiler pressure vessel on test,but believes I have a system leak. Tried a 1litre bottle of a competitor's leak sealer and it didn't work.Thought I'd try a 0.5 litre bottle of Fernox several day's ago.This hasn't worked either so I haven't found it to be the "magic bullet" that others speak of.Will still have to investigate under the floorboards! 12 Nov 2015
Rated 2 out of 5 by Doesn't do the job Have a leak under the concrete floor so decided to try this based on the reviews people have written. To start with it wasn't easy to pour into the radiator. Once done and left the heating on for 30 mins and turned off for 24 hours for moment of truth.... Didn't work at all. I was so disappointed. Even if it has worked still I think it's over priced for the quantity you get, at least they could have thrown the gun to pour the liquid into the rad to make the price worth. Didn't work for me hence the low scoring. 14 Aug 2015
  • 2016-02-10 T07:01:53.702-06:00
  • bvseo_lps, prod_bvrr, vn_prr_5.6
  • cp-1, bvpage1
  • co_hasreviews, tv_14, tr_14
  • loc_en_US, sid_45902, prod, sort_default
Page : 2 next>
2 Questions  2 Answers

Screwfix Q&A

Ask your questions. Share your answers.

 
 
« Back
 
 
Search:
Sort by:
9 Nov 2015
Customer avatar
by
southminster
Read all my Q&A
, DIY
0points
0out of 0found this question helpful.
Was this helpful?Yes0No0

Answers

Answer: 
Hello Edwardy. If you have no expansion tank the best option would be to dose using the F4 Express (61837) as this is designed to go straight into your radiator, rather than an expansion tank.

If you have already purchased the 500ml version, you can either through go through a system filter, such as the TF1 Total Filter, or you can dose using a small funnel to pour into a radiator bleed valve.
10 Nov 2015
+4points
5of 6found this answer helpful.
Was this helpful?Yes5No1
10 Sep 2015
Customer avatar
by
east sussex
Read all my Q&A
, DIY
0points
0out of 0found this question helpful.
Was this helpful?Yes0No0

Answers

Answer: 
Hello Diy4Den, these two products are compatible.
3 Nov 2015
+2points
2of 2found this answer helpful.
Was this helpful?Yes2No0
1 of 1
  • 2016-02-10 T06:56:49.928-06:00
  • bvseo_lps, prod_bvqa, vn_prr_5.6
  • cp-1, bvpage1
  • co_hasquestionsanswers
  • loc_en_US, sid_45902, prod, sort_default
1 of 1

Specification

Download more info (pdf)

Brand Fernox
Colour Green
Manufacturer Guarantee 10 years
Model No F4
Pack Size 1
Product Type Central Heating Leak Sealer
Sealant Adhesive Volume 500 ml
Total Product Weight 572 kg