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

Click here to see information on our delivery service



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 45.
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
Rated 5 out of 5 by from It Works! I've had problems with pressure dropping on my combi boiler for a few years - not a big problem at first but recently was having to re-pressurise every few days. Used this leak sealer and pressure is holding - so far so good. Easy to use and a lot cheaper than getting the professionals in!
Date published: 2017-12-25
Rated 5 out of 5 by from Fixed leak Finally Fixed leak after couple of month. Good product. Reasonable price
Date published: 2017-12-08
Rated 5 out of 5 by from Miracle product Had this problem on my boiler where I had to top up couple times a week for a year. In that time I had replaced the pressure relief valve and a leaky diverter valve but no change. I then came across this ‘miracle’ product after reading a few reviews. Bought the product on the Sunday - I found it easy to pour it into an empty magna-clean (had to fill it twice if pouring all 1 litre of the product). Topped up the pressure and left it around 1 bar. Instructions does state that it can take 24 hours for it work around the system. Well it’s now Wednesday and the needle on the gauge has not moved. I can now honestly say that product does work.
Date published: 2017-11-01
Rated 5 out of 5 by from Great product Used this product the cure a underfloor leak in a sealed heating system via a towel rad advised customer to leave heating on for 4 hours after no pressure drop i would recommend this product along with inhibitor cheers
Date published: 2017-09-13
Rated 5 out of 5 by from Great product Great product works well.Easy to use.Was a bit reluctant to try it but happy I did stopped leaks instantly
Date published: 2017-07-30
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