See more Central heating treatments
Fernox Leak sealer, 500ml
- Seals inaccessible leaks and weeping joints internally.
Features and benefits
- It can make better use of resources to repair rather than replace items
Health and safety
Please note that this item has additional safety or regulatory datasheets available. The product may have possible health and safety hazards covered in these documents. Refer to the container for full information and always follow the instructions.
nilknarf - 1 month ago
Had a small leak behind the heat exchange going into the combustion chamber, lost about 0.1 bar a day so was topping up every day or two. Since the boiler is old and the heat exchange itelf was most of the cost of a new boiler to replace, I figured that a new one was on the horizon. While getting prices I remembered this product existed and thought for £20 it was worth a shot to simply slow the pressure drop down for now. Put it in via a towel radiator plus some inhibitor for good measure while I was there. A day or so later the pressure had stopped dropping and there was no evidence of the leak anymore. I topped back up to just over 1 bar, and that's where it's been when I check each day for about a month now. I know it's not a long term fix, but I can at least put off buying a new boiler for a little longer thanks to this. If you're in a similar situation and have a system that this product is compatible with, then I'd definitely say give this product a go!
Ejayhaich - 9 months ago
Losing 0.5Bar per day in my sealed system. Put this stuff in, pressure stabilised.
Rob the Modeller - 1 year ago
Our heating system started losing 0.1 of a bar (atmosphere) per day. No detectable leaks. Not even via the pressure relief valve. I surmise it is below the concrete floor in the living room. I bought the Fernox Leak Sealer F4 500ml. Only when I got home did I read it was only for up to a 10 single radiator system. I reckon ours equates to 13. Rather than get more, I thought I'd try to get away with one bottle. Initially, it fixed the leak for 48 hours. Then it dropped 0.1 bar. It then stabilised for 4 days before dropping another 0.1 bar over the next 2 days. I added another bottle. No pressure drop since. That's 9 days. One tip for you. Buy the applicator if you intend adding it via a radiator rather than a header tank.
Fernox Leak Sealer
Happy hols - 4 years ago
My central heating system sprung a leak from a pipe/Union sealed in a concrete floor one week before setting off on holiday. I added Fernox Leak Sealer via the header tank after emptying the tank and draining a bucket of water from the system - to ensure the sealer was drawn in to the system. I then ran the heating for a few hours to mix through system. Following morning all dry, no more leak!
The sealer has appearance and consistency of PVA glue so was too gluppy to add via a radiator. There is a version of this sealer for adding via radiator but it's much more expensive. This product did exactly what it promised to do and saved a huge amount of hassle.