For protecting closed loop hydronic heating systems against limescale and corrosion

Sentinel X100 Inhibitor provides protection for clean hydronic heating systems against limescale and corrosion. Suitable for use in all types of indirect heating system, Sentinel X100 Inhibitor will extend the life of the system, ensuring maximum efficiency and minimising fuel usage.

Key features

  • Heavy duty inhibitor
  • Protects against limescale and corrosion
  • TripleTech™ Anti-Corrosion Technology
  • Suitable for all system metals
  • pH neutral formulation
  • Ensures optimum system efficiency
  • Suitable for hard, soft and artificially softened water
  • Helps prevent the formation of hydrogen gas


Designed to make dosing in to the system quicker than ever.


Product Fact Sheet Safety Data Sheet

400ml (discontinued)

Product Fact Sheet Safety Data Sheet


Features and Benefits

  • Quickest dosing means less time on the job
  • No need to drain or depressurise the system*
  • Adaptor included for application via boiler drain valve

More information about Rapid-Dose and how to dose is available here.

*It is only necessary to release system pressure when it is above 33 p.s.i (2.3 bar).


Slimline format to make dosing in to the system fuss free.

Product Fact Sheet Safety Data Sheet


Features and Benefits

  • Easy dosing means less time on the job
  • Smaller size enables easy storage
  • Controlled application using skeleton gun

Limescale and corrosion are the two main causes of hydronic heating inefficiency, leading to radiator cold spots, boiler inefficiency, a noisy system and a number of other problems. Once a system has been prepared using one of the cleaners from the Sentinel cleaning range, it should be protected with Sentinel X100 Inhibitor to prevent limescale build up or corrosion.

Sentinel X100 Inhibitor has TripleTech™ Anti-Corrosion Technology, a unique blend of heavy-duty specialist corrosion inhibitors. Since hydronic heating systems are often made up of a variety of metals, each of these specialist inhibitors provides protection for different metals, delivering unrivalled performance in protection for multi-metal hydronic heating systems.

1 Quart or 1 275ml/9.3fl oz cartridge of Sentinel X100 is sufficient to treat a typical residential system of 25 Gallons. Larger systems should be dosed at 1% of system water.

For best results, systems should be cleaned and flushed with clean make-up water. New systems and those up to 6 months old with Sentinel X300, existing systems with Sentinel X400. If the system is already noisy due to limescale deposits in the heat exchanger, Sentinel X200 should be added together with Sentinel X100.

Open systems: Dose via F&E cistern, via a by-pass feeder or use a dosing vessel.

Sealed systems: If the system is empty, add to any convenient point before filling. If full, use a dosing vessel to inject via the filling loop or other access point.

When using a concentrate cartridge, the product may be added directly to the heating system either via an air bleed valve, or via the fill loop using the appropriate adaptor and a suitable caulk gun.