A radiator leaking from the bottom is often caused by a leaking valve, a loose valve tail nut, or a joint in the pipework just below. In some cases, the radiator itself has corroded from the inside and developed a pinhole leak. Water can also run down from somewhere else and simply drip from the lowest point.
Corrosion and pinholes in the radiator body
Over time, the water inside a heating system can cause steel radiators to rust from the inside. Sludge often settles along the bottom of the radiator, and that is where corrosion can be at its worst. Eventually a tiny pinhole may form, letting water weep out slowly.
You may see a rusty mark, a damp patch along the lower edge, or a small bead of water that keeps coming back. A pinhole in the body often suggests the radiator is coming to the end of its life. Patching it rarely lasts, so replacement is usually the more sensible option.
Valves, tail nuts and pipe joints
Many leaks that seem to come from the bottom of a radiator actually start at the valves on each end. The valve tail screws into the radiator, and a nut joins it to the valve. If the seal on the tail has failed, or the nut has worked loose, water may drip from underneath.
Pipe joints below the valves can leak too. Compression fittings can weep if the pipe has moved, and old soldered joints can corrode. Water from these points often runs down the pipe and drips onto the floor, so it can look as if the radiator itself is leaking.
When the water comes from somewhere else
Water tends to travel before it drips. A leak from a pipe higher up, or from a valve spindle on the same radiator, can run along the underside and collect at the lowest corner. Condensation on cold pipes can also gather and drip, especially in cooler rooms.
Drying the radiator, valves and pipes with a cloth, then holding dry kitchen roll against each joint, can help show where water first appears. A bowl or towel underneath will protect the floor while you look.
If water is near sockets, plugs or other electrics, keep clear and do not touch anything wet. Only switch off at the consumer unit if it is dry and safe to reach, or ask an electrician for help.
Repair, replace or get help
A loose nut or worn valve seal can often be repaired. Corrosion in the radiator body usually means a new radiator. Many homes have a sealed heating system that holds water under pressure, so draining down or opening joints is not a job to guess at. You can find out more about help with a leaking radiator and how the plumbing side is checked. Any work on the boiler itself needs a Gas Safe registered engineer.
If your radiator is leaking from the bottom and you are in Swindon, Emergency Plumber Swindon is happy to take a look at the plumbing side and talk through the options. Call us on 01793 569521.