As a heating and plumbing expert with years of experience in dealing with various heating systems, I can provide you with a detailed guide on how to bleed a radiator with a combi boiler. Bleeding a radiator is a process that involves releasing trapped air from the radiator, which can cause uneven heating or cold spots at the top of the radiator. Here’s a step-by-step guide to help you through the process:

### Step 1: Preparation
Before you start, make sure you have the necessary tools and materials. You will need:
- A radiator key or a flat-head screwdriver
- A towel or cloth to catch any water that may drip out
- Protective gloves (optional)

### Step 2: Isolate the Radiator
Turn off the heating system and let the radiator cool down. This is important for your safety and to prevent damage to the radiator.

### Step 3: Locate the Bleed Valve
The bleed valve is typically found at the top of the radiator, near one end. It’s a small valve with a slot for the radiator key or screwdriver.

### Step 4: Place the Cloth
Place the towel or cloth underneath the bleed valve to catch any water that may come out during the bleeding process.

### Step 5: Open the Bleed Valve
Using the radiator key or flat-head screwdriver, gently turn the bleed valve counterclockwise to open it. You should hear a hissing sound as the air escapes.

### Step 6: Release the Air
Allow the air to escape until water starts to flow out of the valve. This may take a few seconds to a minute.

### Step 7: Close the Bleed Valve
Once water is flowing steadily from the valve, close it by turning it clockwise. Be careful not to over-tighten.

### Step 8: Check the Radiator
After bleeding, check the radiator to see if it heats up evenly. If it’s still cold at the top, you may need to repeat the process.

### Step 9: Re-pressurise the Combi Boiler (if necessary)
If you have a combi boiler or a sealed system, you may need to re-pressurise your boiler after bleeding the radiators. This is done by following the manufacturer's instructions, which usually involve using a filling loop and a pressure gauge.

### Step 10: Restart the Heating System
Once you are satisfied that the radiator is working properly, restart your heating system. This should help to ensure that the radiator heats up evenly.

### Important Notes:
- Always follow the manufacturer's instructions for your specific heating system.
- If you are unsure about any step, it’s best to consult a professional.
- Regular maintenance, including bleeding radiators, can help to prolong the life of your heating system.

Bleeding a radiator with a combi boiler is a relatively straightforward process, but it’s important to take the necessary precautions and follow the steps carefully to ensure that you don’t damage your heating system or radiator.

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If one of your radiators is cold at the top, it probably means that there is air trapped in there and it will need bleeding. ... By restarting your heating system, you should find that the radiator will now be hot. If you have a combi boiler or sealed system, you may need to re-pressurise your boiler.read more >>