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Bleeding Radiators

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Bleeding radiators is the process of releasing trapped air that has coalesced inside your home heating circuit(s).

Why Do Radiators Need Bleeding

Any air that gets in to the system, being lighter than the water getting pumped around your home heating, always tries to reach the highest point it can, usually ending up inside the top of at least one of your radiators. This trapped air causes cold spots in the radiator and reduce the effectiveness of the heating around your home.

By bleeding radiators regularly and at the start of each winter, you can greatly improve the performance of your heating systems and this will make your home warmer – perfect for keeping everything cosy! It is a simple process – follow this Winter Guide from Staunch and Flow.

The Process of Bleeding Radiators

+ Signs That a Radiator Needs Bleeding

All radiators will need bleeding at some point, and a check once a year, at the beginning of the first cold snap that gets you to turn on your heating, will keep everything running smoothly. Once the heating is on and has had time to heat everything up, feel each of the radiators for inconsistencies in heating. The tell-tale signs are that a radiator is cold at the top OR taking too long to heat up.

+ Preparing a Radiator for Bleeding

Before bleeding, turn the heating off and let the radiators cool down completely. This is important – if you try it when the radiator is still warm or have left the heating on completely, this will result in hot water spraying out when bleeding and you may get scalded.

+ Bleeding the Radiator

You’ll need a radiator bleed key (usually with a square indent to fit the valve on the radiator) and an old tea towel or rag. Fit the key to the valve at the top of the radiator and loosen. If air is trapped inside, you’ll start to hear a hissing sound as the air escapes. Make sure you hold the rag around (and especially underneath) the valve entrance to catch any drops of water which also escape.

Once a regular stream of water starts to escape, use the key to close the valve to the radiator as it is now free of air.

Now you need to go back to your boiler and check that the system is still showing enough pressure in the system for the boiler to operate. If you have a pressure dial, there will be a green zone – if the needle is sitting within it, you should be OK. If you have a digital display that can be accessed through the boiler’s control panel, it will give a reading that you can check against the boiler manufacturer’s instructions. If the pressure has dropped slightly, you can top it up using the filling loop. If you are unsure about this step, call Staunch and Flow today.