For older closed loop hydronic heating systems

Sentinel X400 System Restorer is specifically designed for cleaning older closed loop hydronic heating systems. It is a non-acid treatment which restores circulation to radiators and pipework. Its ruthlessly efficient formula shifts built-up magnetite sludge, eliminating cold spots in radiators and restoring proper heat distribution.

Key features

  • Restores systems suffering with circulation problems
  • Eliminates radiator cold spots
  • Prepares older systems for the installation of new components
  • Has a non-acid formula which does not cause pin-holing or leaks
  • Can be used in all types of indirect heating systems, including those containing aluminium


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

Sentinel X400 System Restorer restores a more even heat distribution to the house, keeping the property warmer and bills lower. Reviving an old heating system is a more cost-effective way to return warmth to a property than the installation of a whole new system.

Cleaning an old system before installing a new component also prolongs the effective life of the new component, whether a radiator or a boiler, reducing maintenance and replacement costs.

1 quart of Sentinel X400 is sufficient to treat a typical residential system of 25 gallon. Larger systems should be dosed at 1% of system water. To clean an existing system, Sentinel X400 should be circulated, preferably at normal operating temperature, with all valves open and the pump turned to 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., approximately 3-4 weeks) is recommended, but the product will not clear a completely blocked pipe. There is no limit to the time for which the product can safely be left in the system.

Rapid cleaning may be carried out 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 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.