How to Fix a Leaking Radiator Valve

Radiators often groan and hiss as part of their daily routine, but a puddle on the floor is a sign of a failing seal. The most common culprit is the packing gland, a small nut located directly behind the valve handle designed to prevent water from weeping out around the stem. This isn't a complex plumbing overhaul, but it does require a steady hand to ensure you don't over-tighten and snap the fitting. Done well, this repair takes less than twenty minutes and saves you the cost of calling a professional. The goal is to apply just enough pressure to compress the internal packing material to seal the leak without making the valve impossible to turn in the future. Keep a cloth handy, work slowly, and your radiator will be dry and quiet by the end of the morning.

1. Protect Your Floor First. Place a shallow tray or an old towel directly beneath the valve to catch any potential drips. Ensure the area is well-lit so you can clearly see the valve stem and the gland nut.
2. Spot the Hidden Nut. Look behind the main valve handle where the metal stem enters the valve body. You will see a small, hexagonal nut specifically used for the packing gland.
3. Turn the Nut Clockwise. Hold the valve body steady with one wrench to prevent it from twisting the pipe. Use a second wrench to turn the gland nut clockwise by about a quarter to half a turn.
4. Check for Drips. Wipe the area completely dry with a clean cloth. Observe the valve for five minutes to see if any moisture reappears on the stem.
5. Verify Smooth Operation. Turn the radiator handle fully open and then fully closed. Ensure the valve operates smoothly without binding after your adjustment.
6. Wait for Heat Expansion. Check the valve once more after the radiator has heated up fully. Heat causes metal to expand, which may require a final, tiny adjustment to the nut.