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Quick answer
A leaking radiator valve usually leaks from one of three places: the nut connecting the valve to the pipe, the nut connecting the valve to the radiator (the union), or the spindle where the valve head turns. Loose nuts can often be nipped up carefully with a spanner, holding the valve body steady with a second spanner. Leaks from worn olives, seals or spindle glands, and from corroded valve bodies, usually need parts replacing and often a partial drain down. On sealed systems, check boiler pressure after any leak.
Key takeaways
- Identify where the leak is coming from before doing anything.
- Loose compression nuts can often be tightened slightly with two spanners.
- Spindle leaks may need the gland packing or valve replaced.
- Corroded valves often need replacing, which may require draining.
- Leaks lower pressure on sealed systems; top up after repairs.
Find the source
Dry everything with kitchen roll, then watch where the water appears. Wrap tissue around each nut separately to see which one gets wet.
Pipe nut leaks
The nut connecting the valve to the pipe coming from the floor or wall uses a compression olive. A quarter turn can stop a weep. Hold the valve body with one spanner and tighten the nut with another so you do not twist the pipe. Do not overtighten.
Union nut leaks
The union connects the valve to the radiator tail. A weep here can sometimes be stopped by tightening. If not, the tail may need resealing, which means isolating the radiator and draining it.
Spindle leaks
On manual valves and lockshields, water can seep past the spindle. Some valves have a gland nut that can be tightened slightly. TRV spindle leaks often mean replacing the valve.
Corrosion
Green or white crusty deposits and pitting on the valve body suggest corrosion. The valve should be replaced before it fails.
Isolating a radiator
Turn off both the TRV (or manual valve) and the lockshield (count turns so you can reset balancing). This isolates the radiator so you can work on the union side, although draining the radiator is still needed for many repairs.
After a leak
On sealed systems, check boiler pressure and top up if needed. See how to repressurise a combi boiler. If pressure keeps dropping, see boiler losing pressure but no visible leak.
Book with Gasmaster
Radiator valve dripping? Gasmaster Plumbing & Heating replaces valves and fixes leaks across Stoke-on-Trent, Newcastle-under-Lyme and Biddulph. See our plumbing services.
Frequently asked questions
Is a leaking radiator valve an emergency?
A small weep is not an emergency but should be fixed to prevent damage and pressure loss. A significant leak should be isolated straight away.
Can I use PTFE tape on a compression fitting?
Compression fittings seal with the olive; tape is not the right fix. A worn olive should be replaced.
Do I need to drain the whole system to change a valve?
Not always. Sometimes partial drain down or freezing kits are used. It depends on the system.
Sources
- Water Regulations Advisory Scheme (wras.co.uk)
- Energy Saving Trust (energysavingtrust.org.uk)
Related services
Abdul runs Gasmaster Plumbing & Heating and has worked on boilers, heating and gas appliances across Stoke-on-Trent since 2005. He is Gas Safe registered (reg. 220932), and these articles come from his day to day work in homes and businesses across Staffordshire, Cheshire and Derbyshire.
