A leaking radiator is a household headache that can worsen over time if not treated once it first appears. Even a tiny leak can stain floors, damage walls and gradually push your heating bills up. Most radiator leaks are simple to diagnose and fix, given the right tools. Use our guide below to stop your leak and prevent it from happening again.
Why your radiator might be leaking
A leaking radiator can be caused by a range of issues. Identifying the cause before attempting to fix the leak is important to prevent unnecessary tampering. Reasons your radiator is leaking may include:
- Damaged or loose radiator valves
- Loose, or worn-down, pipe connections
- Corrosion
- Damaged radiator gland
- Faulty bleed valve
- Cracked radiator body
How to fix a radiator leak
- Identify the leak
Start by drying the radiator and the surrounding pipework with an old towel or cloth so you can see where the water is forming. Check the valves, pipe joints, radiator gland and the body of the radiator itself. If the leak seems to be travelling, or you can’t identify the origin, keep in mind that water often runs along pipework, and hidden leaks may need to be identified using specialist equipment.
- Turn off the heating
Before you start taking measures to repair the leak, switch off your heating system and allow the radiator to cool completely. Then close both valves on the radiator to isolate it and stop the flow of water. Place an old towel or tray underneath to catch any drips.
- Fix the leak
The repair process will depend on the cause of the leak. Once you know where the leak is coming from, use the relevant fix below.
Damaged or loose radiator valves
A loose valve joint is solved by gently tightening the nut with an adjustable spanner. Watch that you don’t overtighten the valve, as this could damage the threads and make replacing it the only option. If the valve itself is damaged or worn, replacing it is usually the only reliable fix.
Loose or worn-down pipe connections
Connections can loosen over time, or the rubber washers inside can degrade. Tighten the connection first. If there is still a leak after you’ve turned the heating back on and reopened the radiator valves, then the washer or fitting will need to be replaced.
Corrosion
Corrosion usually appears as rust or bubbling paint on the radiator’s surface. Minor corrosion can be fixed with a radiator repair sealant, but these are only temporary fixes, so a full radiator replacement would be a more suitable, long-term fix.
Damaged radiator gland
If water is leaking from the valve spindle, the gland packing likely needs tightening or replacing. Tighten the gland nut gently, avoiding over-tightening. If this isn’t effective, wrap PTFE tape around the spindle and retighten.
Faulty bleed valve
A bleed valve that won’t seal properly usually just needs tightening. If it’s stripped, cracked, or seized, replacing the valve insert is best.
Cracked radiator body
Cracks cannot be repaired as effectively as other leak causes. Sealants only work to slow the leak for a short term, so replacing the radiator is the only reliable solution. It may be best to consult a professional in this instance, as cracks in the radiator body may suggest pressure issues elsewhere in the system.
- Turn the radiator back on and check for leaks
Once the repair is done, open the valves again and turn the heating back on. Keep an eye on the radiator for a few minutes and replace any wet towels or trays to ensure you can easily spot the leak if it recurs. If the leak continues, the issue may be deeper in the system, or there is something else wrong.
- Call a professional
If the leak continues and the cause isn’t obvious, or repairing the leak is outside of your comfort zone, then an expert can help pinpoint the problem quickly and prevent any more water damage.
How to prevent a leaky radiator in the future
Radiators are not immune to general wear and tear and corrosion as a result of age and usage. However, carrying out proper, regular maintenance can help prevent premature leaks and extend the life of your radiators.
- Regularly bleed your radiators to help remove any trapped air, prevent cold spots and reduce potential strain.
- Consider central heating treatments to clear radiators from the buildup of rust and sludge.
- Keep an eye on signs of wear like damp patches or small leaks.
When you can’t fix the leak yourself or the problem is recurring, professional support is the fastest, safest option. A local qualified plumber will be able to help, but if your leak is not obvious and cannot be found, then the next step is to contact a specialist.
Call a leak detection specialist
At Harmuns, our professional team use advanced tools like thermal imaging, acoustic listening, tracer gas technology and moisture mapping to detect the exact source of a leak without the guesswork, and whilst protecting your home from unnecessary damage.
Got a leak? Contact us today, and we can help prevent it from spreading.