Bleeding a radiator is a simple yet essential maintenance task that helps ensure your heating system works efficiently. Over time, air can become trapped inside radiators, causing cold spots and reducing the effectiveness of your heating. Typically, a radiator key is used to release the trapped air, but what if you don’t have one on hand? In this article, we’ll guide you through how to bleed a radiator without a key using common household tools.

Tools and Materials You’ll Need:

Flathead Screwdriver: This will be used as a makeshift radiator key.

A Towel or Cloth: To catch any water that may drip during the bleeding process.

A Bowl or Container: To collect any excess water.

Pliers or Wrench (optional): In case you have trouble turning the valve.

Now, let’s walk through the step-by-step process of bleeding a radiator without a key:

Step 1: Turn Off Your Heating System

Before you start, ensure that your heating system is turned off completely. This will prevent hot water from spewing out when you bleed the radiator.

Step 2: Identify the Bleed Valve

Locate the bleed valve on your radiator. It’s typically located on the top side, near one end. The bleed valve looks like a small square or hexagonal nut, and it’s where you’ll release the trapped air.

Step 3: Prepare Your Tools

If you’re using a flathead screwdriver, choose one that fits securely into the bleed valve. You want a good grip to avoid damaging the valve. If needed, you can use pliers or a wrench to turn the screwdriver if the valve is particularly tight.

Step 4: Place a Towel or Cloth Under the Radiator

To catch any water that may escape during the bleeding process, place a towel or cloth under the radiator, especially if you have carpet or hardwood flooring.

Step 5: Begin Bleeding the Radiator

Now comes the actual bleeding process:

a. Insert the flathead screwdriver into the bleed valve securely but gently. Make sure it fits snugly to avoid stripping the valve.

b. Hold the screwdriver firmly with one hand to create leverage.

c. With your other hand, slowly turn the screwdriver counterclockwise (left) to open the bleed valve. Be cautious not to turn it too far or apply excessive force to prevent damaging the valve.

d. Listen closely for the sound of escaping air. You’ll hear a hissing noise as the trapped air begins to release.

e. Continue turning the screwdriver slowly until you see a small amount of water start to trickle out. This indicates that all the air has been released, and it’s time to close the valve.

Step 6: Close the Bleed Valve

Once all the air has been released, turn the screwdriver clockwise (right) to close the bleed valve. Again, be gentle and avoid over-tightening. Make sure it’s snug but not too tight to prevent damaging the valve.

Step 7: Check the Water Pressure

After bleeding the radiator, check the water pressure gauge on your heating system. It should be within the normal range. If it’s too low, you may need to top up the water in your heating system.

Step 8: Monitor for Leaks

Inspect the area around the bleed valve for any signs of leaks. If you notice water dripping, use a cloth or towel to catch it, and then tighten the valve slightly. Be cautious not to overtighten, as this can damage the valve or the radiator.

Step 9: Repeat for Other Radiators (if necessary)

If you have multiple radiators in your home, repeat the bleeding process for each one, starting with the radiators that are furthest from the boiler and working your way toward the closest ones. This ensures that all trapped air is released from the system.

Step 10: Turn Your Heating System Back On

Once you’ve bled all the radiators and are satisfied with the water pressure and lack of leaks, you can turn your heating system back on. Make sure all radiators are heating evenly and that there are no more cold spots.


Bleeding a radiator without a key is entirely possible using a flathead screwdriver or similar tools. Regularly bleeding your radiators helps maintain the efficiency of your heating system and ensures that your home stays warm and comfortable during the colder months. If you’re uncomfortable or unsure about performing this task yourself, consider consulting a professional heating engineer to assist you with radiator maintenance.