If your radiator is leaking, the cause is usually a loose valve connection, worn seal, internal corrosion, or pressure imbalance rather than a sudden system failure. Most radiator leaks develop gradually from fittings or joints under stress. In many cases, the issue is local to one radiator, but persistent leaks can indicate wider pressure problems.
The Most Common Places Radiators Leak
Where the water appears often reveals the cause.
1. Leak From the Valve Connection
If water drips where the pipe meets the radiator, the valve fitting may be loose or the internal seal worn.
This is one of the most common causes.
If boiler pressure changes frequently:
→ Why Is My Boiler Losing Pressure?
2. Leak From the Bleed Valve
The small bleed screw at the top of the radiator can leak if:
- It is not fully tightened
- The seal has worn
- The thread is damaged
If you recently bled the radiator:
→ Why Is My Radiator Cold at the Top?
3. Leak From the Bottom of the Radiator
Water appearing along the bottom edge may indicate:
- Internal corrosion
- Rusted seams
- Sludge damage
If the radiator is also cold at the bottom:
→ Why Is My Radiator Cold at the Bottom?
4. Leak From the Radiator Body
Older radiators can corrode internally over time.
Small pinhole leaks may form along the surface.
This usually requires replacement.
5. Pressure-Related Leak
If system pressure is too high, weak points may begin to leak.
If your pressure gauge reads high:
→ Why Is My Boiler Pressure Too High?
Is This Serious?
Minor if:
- Leak is slow
- It occurs at a fitting
- Only one radiator is affected
More serious if:
- Pressure drops regularly
- Multiple radiators leak
- Water damages flooring
Persistent leaks can lower system pressure and affect heating performance.
What You Can Do
If your radiator is leaking, you can:
- Turn off heating temporarily
- Check boiler pressure
- Identify the exact leak location
- Place a container under slow drips
If pressure drops repeatedly, further inspection may be required.
For related issues, see:
→ Heating Problems Explained
→ Why Is My Boiler Losing Pressure?
→ Why Is My Radiator Cold at the Bottom?
→ Why Is My Boiler Pressure Too High?