How to Repair a Leaky Radiator Bleed Valve Quickly and Easily4 min read

A leaky radiator can be a very frustrating issue, especially if it happens often. Fortunately, the problem isn’t always severe. It may be caused by the bleed valve, which can be quickly patched or, maybe less quickly, replaced, pretty easily..

To repair a bleed valve leak, drain the valve and apply plumber’s tape (example on Amazon) to the threads of the male side of the fitting to create a seal. This can stop the leak, but replacing the valve is recommended to completely solve the issue. Some cases will require professional assistance.

Don’t panic if your radiator has a leak. The issue is pretty common, and the process to fix it is relatively straightforward. Let’s take a look at everything you need to know.

Why Is Your Radiator Leaking?

Radiators can leak from several different places. Some common locations for leaks are the valves and pipes. Leaky radiator pipes are a significant issue that typically requires professional assistance, but valves are much easier to deal with.

Regardless of whether you need to fix or replace the valve, you’ll first need to determine where the leak is coming from.

Start by wiping down the radiator with a cloth that has a slightly different color when wet (or even grab some toilet paper). Wipe every inch of the radiator until it’s completely dry. Pay attention to where the toilet paper gets wet to pinpoint the leak, and then move on to the steps below.

It’s almost certainly your bleed valve that’s leaking, but this step will help you confirm that before going any further.

How to Fix a Radiator Bleed Valve Leak

Female hand with rag cleaning water from heating radiator leak

The bleed valve is the most common area for a radiator leak, since it’s constructed to allow air and water out of the device.

Sometimes, a bleed valve in the “mid open” position can leak; the valve must be fully open or closed to function properly.

So, why else does the bleed valve leak? The spindle packing inside the valve’s radiator can become damaged or worn out over time.

Regardless of the issue, you’ll need to fix or replace the valve. Here’s how:

  1. Turn off your heat and radiator. Give your radiator time to cool down.
  2. Leave the bleed valve open to drain all of the water possible. Radiators can hold over 10 liters of water, so you’ll want buckets, bowls, and towels.
  3. Turn off the supply valve and the lockshield valve.
  4. Next, unscrew the union nut and drain any residual water. The union nut connects the feeder pipe and the radiator.
  5. Apply plumber’s tape around the male side of the valve. This will create a temporary seal.
  6. Lastly, tighten the union nut and reopen any valves you closed. The radiator should turn on without any leaks. Afterward, you can close the bleed valve.

Note: Patching the bleed valve is typically used as a temporary solution. In most cases, replacing the bleed valve after patching it up is recommended to resolve the issue entirely.

How to Replace a Radiator Bleed Valve

Plumber repairing a radiator pipe

Fortunately, the bleed valve is an easy component to replace on a radiator, and the project doesn’t take more than 30 minutes.

What You Need to Start

Step 1: Isolate Your Radiator

To start, turn off all the valves to isolate the radiator from the rest of your system.

Find the lockshield valve and turn it clockwise to disable it. The lockshield valve is typically found on the water return pipe. Ensure you count the turns, as you’ll need to turn them later on.

If you have manual valves on your radiator, you’ll typically find them on the flow side of the device. Be sure to note the settings before twisting it clockwise to disable it.

For thermostatic radiator valves (TRV), remove the valve head by unscrewing it and utilize the decorator’s cap to turn it off completely.

Step 2: Prepare Your New Value

Take your new valve and hold it in your hand with the head facing you and the threads facing away. Apply the PTFE tape around the thread four to five times, going counterclockwise.

Step 3: Remove Your Old Valve

Now, you’ll need to remove the old valve. You’ll want to prepare the area for catching the water with buckets, towels, and dishes. Remove the old valve to drain the water.

For bleed screws, you can use a screwdriver or radiator key to remove them. You’ll need an adjustable spanner to unscrew and remove bleed valves.

Step 4: Install Your New Valve

Afterward, you can install your new valve, depending on the type. Install bleed screws clockwise if you have one.

You’ll need to screw it by hand to start for bleed valves. Next, take your adjustable spanner around the exterior of the bleed valve to secure it by turning it clockwise.

Step 5: Reset Your Valves

You’ll need to reset the valves you closed in the first step. Reset the lockshield valve to its original position using the number of turns you counted to close it.

For manual valves, turn it back to the original position using the turns you counted as well.

If your radiator has a TRV, simply reverse the steps you used to disable it to reset the valve. Lastly, turn on the isolator if you have one installed.

Step 6: Inspect for Leaks

The last step is to inspect for any leaks and adjust. You can tighten your new bleed valve with the adjustable spanner if it’s still leaking. However, you can return to the first step and apply more PTFE tape if tightening doesn’t fix the issue.

Finally, ensure that your radiator is evenly hot at the top. If it isn’t, disable the heating and let it cool completely before attempting to bleed it once more. You may need to top off the system to the correct pressure to resolve the issue.

Other Possible Leaks

The steps above should help resolve a leaky radiator. However, other locations on the radiator can cause leaks as well. Some common leaks include the following:

Valve Spindle Leaks

The valve spindle is the shaft center of the valve. The valve spindle is most likely the culprit if you follow the steps above and still have issues.

Unscrew the gland nut and apply the plumber’s tape over the spindle. Afterward, gently push the shaft deeper into the valve and reapply the nut gland to finish.

Corrosion Leaks

Corrosion is another common issue that causes leaky radiators. The metal radiators hold water and can develop internal leaks and corrosion over time.

You can temporarily resolve this issue by patching it with plastic resin. However, you’ll need to replace the radiator and use a rust inhibitor (on Amazon) to fully solve the problem.

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Hi, I'm Ed, and I run BuildFanatic! I enjoy providing the best possible information on a range of home improvement topics.

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