How do you bleed a radiator on a Pressurised system?

To bleed a radiator on a pressurized system, carefully release trapped air using the bleed screw until water appears. Here's a breakdown:

Steps to Bleed a Radiator

Here's a step-by-step guide to bleeding a radiator on a pressurised system:

Preparation: Gather a radiator key (or a small flat-head screwdriver, depending on the bleed screw type) and a cloth to catch any escaping water.
Locate the Bleed Screw: This is usually a small valve, often with a square or slotted head, located at the top of one end of the radiator.
Loosen the Bleed Screw:
- Holding a cloth to catch any water spillage, slowly loosen the bleed screw on the radiator (do NOT remove the bleed screw).
Listen for Hissing: You should hear air hissing out of the valve. This is the trapped air escaping.
Wait for Water: When all the air has been removed from the system, water will start to come out.
Close the Bleed Screw: Once water starts to emerge, immediately close the bleed screw. Be careful not to overtighten it.

System Pressure: After bleeding your radiators, check the pressure gauge on your boiler. If the pressure has dropped significantly, you may need to repressurize the system. Consult your boiler's manual for instructions on how to do this.
Safety First: Hot water can scald, so be cautious when bleeding radiators, especially if the system has been running recently.
Persistent Problems: If you find yourself frequently needing to bleed your radiators, there may be an underlying issue with your central heating system. Consider consulting a qualified heating engineer.
Sequential Bleeding: Start with the radiators that are furthest away from the boiler, then work your way back towards the boiler. This helps to ensure that all the air is removed from the system efficiently.

Problem	Possible Cause	Solution
No air comes out	Radiator already bled	Check other radiators. If all are bled and problems persist, consult a heating engineer.
Only air comes out indefinitely	Low system pressure	Check boiler pressure and repressurize if necessary. Look for leaks in the system.
Water leaks from bleed screw	Damaged bleed screw or valve seat	Replace the bleed screw. If the problem persists, consult a heating engineer as the valve seat might be damaged, requiring more extensive repair.