Sentinel Internal Leak Sealer 1Ltr Product Code: 99730

Internal Leak Sealer for small inaccessible leaks and weeping joints in all types of indirect heating systems including those containing aluminium components. Compatible with elastomers.


  • 1 Year Guarantee
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Safety Data Sheet
Additional Information
Technical Specification
  • Brand : Sentinel
  • Product Type : Internal Leak Sealer
  • Volume : 1 Ltr
  • Pack Size : 1
  • Manufacturer Guarantee : 1 Year Guarantee
  • Pieces in Pack/Case : 1
Product Contents
Delivery & Returns


Standard delivery service up to 3 working days: €8.95

Free delivery on all orders over €70.00

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Hopefully you won't need to return an item, however, if you do, it is our aim to make this as simple as possible. By following the guidance below you can help us to help you when a product is not what you expected, or is faulty. Your statutory rights are not affected by this guidance.


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€17.95 Incl. 23% VAT

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Sentinel Internal Leak Sealer 1Ltr is rated 4.7 out of 5 by 50.
Rated 5 out of 5 by from Great Value A great product, easy to follow instructions. Good price.
Date published: 2018-10-07
Rated 5 out of 5 by from Well worth it I used 2 bottles of this in a newly refurbished rental property, the system was loosing enough pressure each week to shut the system down with no leaks evident. It took a day or 2 to circulate properly and start working. That was 6 months ago now & I haven't had to even top the system up 1 time. Worked perfectly for me
Date published: 2018-06-28
Rated 5 out of 5 by from Successful last ditch attempt Before calling in insurance claim for a leak detection company (some pipe work under tiled floor which couldn't be accessed) finally tried this product. There had been a steady slow reduction in pressure of .3 bar every week. Large house but was able to isolate which area leak was happening. Added 2 litres and ran hot for two days then opened up remainder of house heating. Leak stopped! This was 4 months ago and so relieved that I thought the product worth promoting.
Date published: 2018-05-30
Rated 4 out of 5 by from Seems to work ok Used this in both combi and traditional heating systems. Took a while to seal a leak in the trad system but did it in the end. Combi system was gradually losing pressure (quite slowly) so it will be a while before full confidence is achieved.
Date published: 2018-05-09
Rated 5 out of 5 by from Great! I bought this today and added it to my Combi boiler system, it was a last-ditch effort before having to rip up my wooden floors and smash the screed below it to gain access to the pipework My 8-year boiler was losing pressure and I needed to top it up approx every 2 hours, the pipework is about thirty years old and the radiators vary in age I really had no faith in the product, rest assured it lived up to the hype, it sealed the leak straight away, I don't know how long it will last but I am over the moon at the minute, I have now ordered the Sentinel X200 and X800 products to cleanse and maintain the heating system.
Date published: 2018-04-14
Rated 5 out of 5 by from Sentinel leak sealer Had a bad leak from a radiator pipe into the valve. Added the leak sealer through a towel rail after syphoning out a litre of water. Leak stopped within a couple of hours saved a much bigger drain down and repair would highly recommend.
Date published: 2018-02-18
Rated 5 out of 5 by from Wow - stop leak within 30 mins Bought new radiator but it had a minor drip coming from the body with no access to it, should of really taken back this rad (from a another retailer) but the chew to drain down, remove from wall, and solid fixed brackets, etc, etc I thought it was worth a go. Wow very impressed work straightway. I’m keeping an eye on it... but it’s done the job so far after 3 days
Date published: 2018-02-12
Rated 5 out of 5 by from Perfect solution This product actually works restored the pressure on my combi boiler saving me fortune in plumbing bill, certainly recommend this product for small inaccessible leaks
Date published: 2018-02-07
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