Should radiator valves be fully open?

The main function of radiator valves is to control the flow of water that passes in and out of your radiators. You might therefore think that all valves on all your radiators should remain fully open all the time in order to allow the free flow of water. However, while this sounds good in theory, this could lead to an imbalance in your heating system whereby some radiators get hotter than others. In this article, we'll look at how to have a balanced heating system so that all your radiators get equally hot. Your radiator valves have an important part to play in this process.

What are balanced radiators?

In order to ensure your radiators distribute heat around your home evenly, you need to make sure your heating system is balanced. In an unbalanced heating system, the radiator closest to the boiler is likely to get very hot, while other radiators in your home get progressively cooler. This is often why rooms that are furthest away from the boiler often struggle to get warm.

Every radiator has a lockshield valve, which is specifically designed to control how much water goes into your radiator. On most radiators, this is the valve you can't turn by hand. By closing a fully-open lockshield valve by a few turns (with a pair of grips or screwdriver), you can slow down the rate at which water enters the radiator and reduce the speed with which it gets hot. This is useful to do to the radiator closest to the boiler as it will stop it getting too hot too quickly and will encourage more water to flow further down the pipe network into the radiators that struggle to warm up.

Check the temperature

To accurately and quickly establish how hot each of your radiators is getting, you should clip two radiator thermometers onto your radiator pipes. One should be on the pipe that allows water into the rad and the other should be clipped onto the pipe where water flows out of the rad. This will show you the difference in temperature between water entering and exiting the radiator.

Ultimately, it would be best if the temperature difference between the two is as close to 0°C as possible. Closing the lockshield valve by a few turns will help to achieve this. This can be done on every radiator and each lockshield valve may have to be open or closed to a different degree in order to achieve a temperature balance. Hopefully this illustrates why your valves should not necessarily be fully open all of the time.

• Further reading: The Complete Guide to Radiator Valves

At this point, it's worth noting that the hot water for your radiator doesn't flow through one radiator and then onto the next one. Instead, hot water comes from your central heating system's main flow pipe with some of the water being taken through smaller pipes off into the other radiators. The water pass through the radiator and exits via the return pipe which takes the water back into the main flow pipe.

The video below shows a professional plumber explaining how to balance your radiators and how water flows around your central heating system.

Once you have gone through the process of balancing your radiators, you should find that all of your radiators get nice and hot and there is no room in your house that is colder than the others. However, if you think that the radiator balancing process is a bit too complicated, please don't attempt it yourself. Call in a professional and they will be happy to sort out this matter for you.

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