Central Heating Leak Detection and Repairs

Sealant that fills leaks from the inside of a central heating system can be a practical short-term solution in certain situations. Our experts recommend using them only when a leak can not be accessed for immediate repairs, there are no compatibility concerns, and there are no other options to prevent water damage.

There are several reasons why the use of leak sealers is not recommended:

1. Risk of Blockages: Sealant can cause blockages in the narrowest parts of a boiler and heating system, such as heat exchangers, valves, and pumps. Power flushing may be needed to clear a blockage, and parts might need to be replaced.
2. Invalid Boiler Warranty: Due to the risk of damage that sealers can cause to a gas boiler, their use can invalidate the warranty provided by some boiler manufacturers.
3. Not Compatible: The use of some sealers is incompatible with some heating systems. Microbore systems, featuring narrow-gauge pipework, are susceptible to blockage with certain sealers. There are also risks associated with the way some sealers react with chemical inhibitors added to a heating system to reduce internal corrosion.

Most home insurance policies contain a clause for “trace and access”. Sudden and accidental damage from radiators, pipework and boilers is usually covered. However, if a leak occurs due to a lack of maintenance, corrosion, or wear and tear, the repair cost is unlikely to be covered. Incorrect installation and damage resulting from negligence can also be reasons for a claim to be refused.

Insurance policies cover different aspects of a leak’s investigation, access, repair, and reinstatement phases. Therefore, it is recommended that you read your policy or contact your insurer for further details. If your policy includes an “escape of water” clause, but not “trace and access”, the investigation to find a hidden leak might not be covered.

Read more on making a successful “trace and access” claim in our comprehensive guide.

If a leak in a central heating system is suspected, but not visible, there are some checks you can make before booking a Gas Safe-registered heating engineer:

1. Look for water leaking from the boiler. You can use a paper towel to check for water tracking along pipes. Blue towels are good because any trace of water on them is immediately apparent.
2. Check the exposed parts of the heating system, such as radiators, valves and pipework.
3. Check the pressure gauge on your boiler; it will drop if there’s a leak. However, don’t assume that a drop in pressure means there is a leak.

A heating engineer can check the boiler to establish if there’s a fault causing the pressure to drop. If checks on the boiler and the exposed parts of the system do not reveal a leak, a non-invasive investigation will be necessary to locate a leak in the concealed parts of the system.

Pinhole leaks in a radiator can be complicated to find visually. They might be out of sight, and water could be tracking slowly along the back of a pipe. The nature of pinhole leaks means that water might not be dripping from the radiator. If it’s on, the water might even evaporate before enough collects for a droplet to form.

The best way to check for radiator leaks is to wipe the radiator panel, the bottom of it, the valves, and the connecting pipework with a paper towel. Blue paper hand towels are the best to use because any amount of water shows up immediately as a dark patch on them.