A radiator described as 'self-bleeding' is fitted with self-bleeding radiator valves. A self-bleeding valve automatically vents excess air trapped inside a radiator. A radiator with a self-bleeding valve means homeowners no longer have to manually vent the excess air – a process commonly known as bleeding – from the radiators (or pay a plumber to do it). If you're not sure what you’re doing, bleeding radiators can be a laborious activity and can lead to wet clothes, floors and walls.

Radiators with manual valves can be fitted with self-bleeding valves. Self-bleeding valves can be purchased for most types of radiators used in homes today and these valves are not difficult to fit. Anyone with a modicum of DIY skill will be able to install a self-bleeding valve. There’s no need to shell out for a plumber… unless you really want to.

Installing a self-bleeding valve on a radiator assures problems resulting from trapped air will be a thing of the past. A self-bleeding valve means no more bleeding and allows the entire heating system to work with greater efficacy. Greater efficiency usually results in lower energy costs, lower maintenance, and an increased longevity of the heating system.

Why Do Radiators Need Bleeding Anyway?

Have you ever noticed a radiator that is cold when the heating is on? The entire radiator may be cold (or sometimes just the upper half) and this problem is most often caused by trapped air. Air is lighter than water and as it rises towards the top of a radiator it forces the hot water down. A large amount of trapped air may displace all the hot water in a radiator and the radiator becomes cold to the touch even when the heating is set to high. A smaller amount of trapped air will only force some hot water down resulting in just the top half of a radiator cooling down.

Another effect of trapped air in a heating system is a gurgling, or banging, sound when heating is turned on. These sounds can continue until any trapped air finds its way to the top of the heating system. The eerie sounds are similar to a horror movie haunted mansion where old rusty piping clanks and groans!

As previously mentioned, a trapped air in a heating system can cause the system to become inefficient. A heating system has to work a lot harder to build up the temperature required in a home when air is being pushed around it. Additionally, trapped air can lead to a premature corrosion of pipes and this may lead to increased maintenance costs.

How Can A Self-Bleeding Radiator Valve Help?

The whole concept of a self-bleeding valve is quite clever yet simple to understand. Any air trapped in the radiator is constantly trying to push its way to the top. The valve is located at the top (on most radiators) and air pushing against the valve causes the valve to open and the air is released. Air continues to be released until there is only water left. When water comes into contact with the valve it cause the valve to close. The valve will remain closed as long as it’s in contact with water and this prevents any water leaks from occurring.

Air enters the heating system when the system replenishes its water level. When excess air finds its way to a self-bleeding valve, it will be vented. Manually bleeding radiators becomes a thing of the past.

How Many Valves Are Needed?

In an average home (three bedrooms), two self-bleeding valves should be sufficient. One valve is fitted to the radiator nearest to the boiler (or as close as possible). A second valve is fitted to a radiator located on the other floor. Two self-bleeding valves is just a recommendation. A larger home, or a home with a substantial trapped air issue, may necessitate more valves. Best practice would be to have a self-bleeding valve fitted to problematic radiators as well as the advised amount. You could even go as far as having a self-bleeding valve fitted to every radiator in a home.

The Two Main Types Of Self-Bleeding Radiator Valves

The most popular models of self-bleeding valves are the HV30C and the MICRO. Both models are made by Aladdin. You may be able to find cheaper generic valves; however, it’s wise to stick with proven brands when purchasing valves. The HV30C and MICRO models can both be bought for under £10 and are easily fitted by anyone with DIY confidence.

The HCV30C valve is for modern style radiators. The MICRO will fit a majority of older radiator models (such as the old cast iron railing style). Aladdin makes a third type of self-bleeding valve, called the ALD02. The ALD02 is for upright towel heaters.

Manually bleeding radiators has never been much fun. But the affordable price, performance, and easy installation of self-bleeding valves means there really is no need for you to manually bleed a radiator ever again.