How To: Seal a Leaking Central Heating Pipe or Joint

I want to know how to seal a leaking central heating pipe, joint, or fitting

About the problem

Anybody who’s ever been presented with leaking central heating knows the pain of finding a reliable temporary fix whilst they source a more permanent one. It may be that the leak is almost unnoticeable and doesn’t require immediate action.

Whether it’s a worn seal, bad jointing or a leak caused by the thawing process following a freeze, small leaks or weeping joints can be easily fixed using one of Sentinel’s two leak sealing products.

The solution

Please note that these methods are NOT suitable for use on potable water systems and should be used for central heating systems ONLY.

For minor leaks and weeping joints:

Apply Sentinel Leak Sealer to the system. To dose into a pressurised system, we recommend the use of the Rapid-Dose™ version of this product. Dose via the boiler filling loop or a radiator, following the instructions provided with the product. This video shows in more detail how to add Rapid-Dose™ products to the central heating circuit.

For larger leaks:

For minimising the damage of larger leaks, apply Sentinel Seal X to form a water-tight seal in just half an hour. Unlike Sentinel Leak Sealer, Sentinel Seal X is an external sealant. Here’s the process for applying it:

  • Ensure pipework is clean. Any rust, dust, grease, oil, or other dirt should be removed in order to achieve the best seal possible.
  • Relieve system pressure if you haven’t already done so.
  • Apply the product as follows:
    • Small leaks: apply directly onto pipework.
    • Burst pipes or larger leaks: apply liberally onto a cloth and wrap tightly around the pipe.
  • Replace the cap immediately to prevent the remaining product from curing inside the tube.
  • Spray the sealant with water to aid the curing process.
  • Once curing is complete, restore water pressure.

Keeping a can of Sentinel Rapid-Dose™ Leak Sealer and a tube of Sentinel Seal X handy in the van can help you to stay on top of weeping systems though internal and external leak sealers should be regarded as a temporary solution to an underlying problem which it is prudent to ultimately repair.

However, preventative action is equally as important being prepared with a solution. The central heating system should be cleaned and then treated with corrosion inhibitor to the correct level in order to prevent corrosion-related leaks.

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