A leaking radiator valve can often be repaired, especially if the leak is from a loose nut or a worn spindle seal. Where the valve body is cracked, corroded or seized, replacing the valve is usually the better option. The right fix depends on exactly where the water is coming from.
TRVs and lockshield valves
Most radiators have a valve at each end. One is often a thermostatic radiator valve, or TRV. The Energy Saving Trust explains that TRVs sense the air temperature and adjust the flow of hot water into the radiator, which lets you control each room.
The valve at the other end is usually a lockshield. It is set once to balance the system and is often hidden under a plastic cap. Both types can leak, and the causes are often similar.
Where radiator valves usually leak
The spindle is the small pin or shaft that moves to open and close the valve. A seal, often called a gland, stops water escaping around it. When the gland wears, water can weep from the top of the valve, especially when the heating is on.
The valve-to-tail nut joins the valve to the short tail that screws into the radiator. If this nut is loose, or the seal on the tail has failed, water may drip from the joint. The connection to the pipework below is usually a compression joint, with a nut and a brass olive. These can weep if the pipe has moved or the olive is worn.
Older valves may also leak through the body itself if it has corroded or cracked.
Reseal, tighten or replace?
Some leaks can be stopped by carefully tightening a nut or renewing a gland seal. It is easy to overtighten, though, which can crack fittings or squash the olive. If the seal on a tail has failed, the joint may need taking apart and remaking.
When the valve body is damaged, or an old valve no longer turns, a new valve is often more reliable. Replacing a valve may mean partly draining the heating system, so the work can be done without water pouring out. Some systems are easier to isolate than others, which affects how long the job takes.
What it means for your heating system
Many homes have a sealed heating system, which holds water under pressure. Losing water from a leaking valve can lower that pressure over time. After draining and refilling, radiators may need bleeding and the system may need repressurising, following the boiler manufacturer’s instructions.
Any work on the boiler itself needs a Gas Safe registered engineer. For the valves and pipework, you can find out more about repairing a leaking radiator valve and what the checks involve. In the meantime, a towel or bowl under the valve can protect the floor.
If a radiator valve is leaking in your Swindon home, Emergency Plumber Swindon can take a look at the plumbing side and talk you through what might help. Call us on 01793 569521.