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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€18.45 Incl. 23% VAT

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Sentinel Internal Leak Sealer 1Ltr is rated 4.7 out of 5 by 61.
Rated 5 out of 5 by from Dripping boiler Had an intermittent leak from my boiler , added this to the towel rad and hey presto more leak !! Only been a couple of days so not sure if it will hold but so far so good ....very pleased !!
Date published: 2019-04-02
Rated 5 out of 5 by from Works a treat I was topping up my combi boiler twice a day by the time the leak was realty bad. As the leak was under a sealed floor it was Impossible to access. After draining enough of the system to put in 1ltr of the leak seal in an upstairs towel rail, topped the system back up. Ran the system over the weekend on usual times. By Monday the pressure in boiler has been maintained. Happy days! I would defiantly recommend.
Date published: 2019-03-11
Rated 1 out of 5 by from Failed to seal the hidden leak I used the product as directed. However, I cannot recommend this product as its application has had no impact on the rate at which water continues to drain from the central heating system.
Date published: 2019-03-05
Rated 5 out of 5 by from Top Leak Sealer Combi boiler system was losing pressure but couldn’t find where. After adding and running this through, all sorted and now no pressure drop at all.
Date published: 2019-03-03
Rated 4 out of 5 by from Leak sealer Had a problem with a combi boiler heat exchanger pressures kept going down. This stuff seems have fixed it. Most people said it was a new boiler but on day 2 I don't think so
Date published: 2019-02-26
Rated 5 out of 5 by from Seems to work Have to admit I was sceptical but a slow leak does appear to have stopped thanks.
Date published: 2019-02-16
Rated 5 out of 5 by from It works Finally managed to cure the loss of pressure in the CH system with a double dose.
Date published: 2019-02-01
Rated 5 out of 5 by from This is brilliant! The pressure in my boiler has been dropping every day for the past 6 months and my plumber recommended I try sentinel. I was certainly sceptical but seems to have fixed the leak and the the boiler has been fully pressurised for the past 2 weeks! One happy customer!
Date published: 2018-12-27
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