VENTING VS BLEEDING A RADIATOR: WHAT'S THE DIFFERENCE?

January 2019

In the same way a gas boiler needs to be serviced annually, radiators should also be regularly maintained to ensure they remain in peak condition and operate efficiently.

With central heating systems, air bubbles can get trapped in the system and prevent hot water from circulating effectively. This means that radiators don’t get as warm as they should and take longer to heat the property.

In this instance, a traditional steel panel radiator would need to be bled to release the excess air from the system. However, maintaining one of our Low-H20 radiators is slightly different. Here’s how:

Low-H20 radiators contain a tenth of the water compared to a standard steel panel radiator, so they waste less heat and react at least three times faster to fluctuations in ambient temperature. So, they heat up immediately if the temperature falls below the set level and stop emitting heat as soon as that same comfort level is reached.

This means they need to be vented, rather than bled, to free excess air from the system. The process takes a bit longer than bleeding but is still very straightforward. All you need is:

– Flat bladed screwdriver
– Sponge or absorbent cloth
– Allen key
– 10mm spanner

Then simply follow these 12 simple steps:

1 Ensure the radiator has been pressure tested, drained and is now empty
2 Close TRV and lockshield
3 Open then air vent on the heat exchanger using a flat bladed screwdriver
4 Open TRV to approx. 10% to fill radiator slowly
5 When water is present at the air vent, close the air vent
6 Open TRV and lockshield fully
7 Run pump for approx. 2 hrs
8 Switch off pump
9 Close TRV, leaving lockshield open
10 Open air vent until water is present, then close it
11 Repeat steps 6 – 10 until all air is vented
12 Open TRV and run system normally

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