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Sentinel X400

Specifically designed for existing systems, Sentinel X400 System Restorer is a non-acid treatment for cleaning older heating systems, restoring circulation to radiators and pipework.

A ruthlessly efficient way to eliminate the build-up of magnetite sludge, X400 is the quick and easy way to eliminate cold spots and restore full heat emission. Helps to improve and maintain system efficiency and conserve fuel.  New systems should be cleaned with Sentinel X300 System Cleaner or X800 Jetflo Ultimate Cleaner.

  • Restores systems with circulation problems.
  • Eliminates radiator cold spots.
  • Can be used in all systems.
  • Prepares existing systems for the installation of new boilers, pumps or panels.
  • Does not cause pin-holing or leaks.

Sentinel X400 is a non-acid formulation which can be used in all types of indirect heating systems including those containing aluminium components.

Sentinel X400 is also available in Rapid-Dose™ or Concentrate format.


  • 1 litre bottle
  • 10 litre cubitainer
  • 20 litre cubitainer


1 litre of Sentinel X400 is sufficient to treat a typical domestic system of  up to 10 radiators. Larger systems should be dosed with 2 litres. To clean an existing system in accordance with BS7593: 2006 Sentinel X400 should be circulated, preferably at normal operating temperature, with all valves open and the pump turned to a maximum flow for a minimum period of 2 hours or until satisfactory performance is restored. Where systems are badly fouled, a longer period of circulation (e.g., up to 4 weeks) is recommended, but the product will not clear a completely blocked pipe.

The product is not aggressive and can be safely left in the system for extended periods.

Rapid cleaning may be  performed if Sentinel X400 is used in conjunction with a power flushing device.

Flush the system before refilling and treating with Sentinel X100 Inhibitor or Sentinel X500 Inhibited Antifreeze.


Open Systems: Dose via F&E cistern, via a by-pass feeder or use a Sentinel Dosing Vessel.
Sealed Systems: If the system is empty, add to any convenient point before filling. If full, use a Sentinel Dosing Vessel to inject via the filling loop or other access point.

Physical Properties

Appearance: Yellow to brown liquid
Odour: Mild
Specific Gravity: 1.020 (20?C)
pH (concentrate): 7 (approx)
Freezing point: -1?C