Diagnose central heating pipe leaks

It's no fun when you've got water leaking from pipes. Find out how to plug that pesky leak before it goes too far.

Before you begin

Find your stop tap and turn it off. The stop tap cuts off the water supply to your house and is normally found under a sink or in the garage. If you have a storage tank, the stop tap will be close to the tank either in the airing cupboard or roof space.

If you have a drain tap also turn this off. This should be located near the stop tap and will drain the pipes once the water supply has been switched off.

Identify the location of the leak

Identify where the leak is coming from. Is the leak at a pipe joint or connection or is there a hole in a section of pipe? Once you've determined the location of the leak follow the instructions below.

Leaks from connections or joints

First you need to check if the joint has been filled with molten solder. If so, you won't be able to tighten it and may need to get the pipe replaced. However, most leaking pipe joints have compression fittings that can be repaired using a spanner or wrench. To do this:

  1. Tighten the joint slightly, no more than a quarter turn.
  2. If this doesn't stop the leak, don't tighten it any further as this will damage the joint.

If the pipe is still leaking you can isolate the area by closing the valves on each side of the boiler, or drain the system to below the leak. Use PTFE tape to tighten connections:

  1. Undo the nut on the joint and pull out the pipe slightly.
  2. Wrap two or three turns of PTFE tape around the face of the olive where it meets the joint.
  3. Tighten the nut again.

Leaking pipes

If the pipe is leaking from a section without joints or connections it will probably need repairing or replacing. You can implement a short-term fix by tying a rag around it, or using a sealant available from a DIY shop. However, a proper repair will involve draining the system and replacing the damaged pipe.

Tips for the future

  • Heat your home
    You should regularly turn on the heating in your home. This will prevent damage to pipes and tanks, which can be caused by cold weather. Pay attention to those rooms which aren't used very often.
  • Service your boiler
    It's also a good idea to have your central heating system and boiler serviced regularly by a Gas Safe registered professional.

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