Why is my radiator whistling?

UK Home Improvement

Why is my Radiator Whistling?

Radiators perform an extremely important role in every home. 

When winter approaches and the temperature inevitably dips, you will want a reliable central heating system that effectively heats your house and doesn’t leave you, literally, in the cold. Fortunately, if your radiator has an issue it’s normally pretty obvious. 

Radiators that have problems can become loud, making all kinds of unusual sounds. A whistling radiator is one sign that something is not quite right. 

If you’ve noticed this phenomenon and are wondering ‘why is my radiator whistling?’, then you’ve come to the right place.  

A whistling radiator can signify a wide range of issues, and in this blog, we’ll explore some of the reasons why this is occurring. 

Why Is My Radiator Whistling? 

A whistling radiator can indicate a variety of different issues. 

This includes the following:

Water flow rate is too high 

One of the most common reasons for a whistling radiator is that the water flow rate is too high. In the short term, this is usually an easy fix. 

You can turn the radiator valve on completely and this will typically prevent the whistling from happening. However, this will mean that you have to heat the radiator to capacity, something you may not want to do.

If the issue persists, you will need to call in professional help.

Limescale has built up

Limescale is the scourge of many household appliances, and radiators can also fall victim to it. For those unaware, limescale is a hard, chalky deposit made from calcium carbonate that often builds up in kettles, washing machines, pipes and radiators. 

It is a particularly common occurrence in areas of the UK that have hard water. In terms of radiators, hotspots inside the system are particularly susceptible to limescale build-up, and this can lead to a whistling sound being emitted. 

You can descale a radiator by adding descaler to the feed and expansion tank. Then, you should drain the system by adding fresh water to the tank. If this still hasn’t worked, you probably need a more invasive solution that a plumber or engineer can provide. 

The drain valve is open 

A whistling radiator could also indicate that a drain valve is open. Sometimes they’re left slightly open after being used, and this causes a whistling sound to occur. Turn all your valves anti-clockwise to ensure they’re properly closed. This should stop the whistling from happening if the valve has caused the sound.   

If the whistling continues, it’s likely you have a different problem.

Air is trapped inside the system 

Another reason that your radiator may be whistling is because of air that has become trapped inside the system. 

This can happen if you haven’t used your radiators in a while, and is quite common in the autumn time when people might start to consider using their heating again after the summer months. 

When heating the system after this time, the air can travel through the radiator making little clicks and whistles that you may notice. 

If ignored, this issue could result in a leaking radiator or the radiator not warming up. 

Try and address the problem by first tightening the bleed screw. If this doesn’t change anything, then it’s likely a sign that air has indeed become trapped. Stay by the radiator as some water may leak out. After this has happened, close the bleed screw again and the problem should be resolved. If it remains persistent, consider consulting a professional. 

You have faulty parts 

Faulty parts are another common cause of a whistling radiator. If you’ve checked all of the above, you may have an issue with the radiator vent which is causing the noise to occur. 

You can normally get a replacement from your local hardware or DIY store, but we’d always recommend calling in a professional plumber or engineer to carry out the work. 

Is A Noisy Radiator Always Bad?

No. Just because your radiator seems particularly noisy, it doesn’t mean it necessarily has a fault or is dangerous. 

In fact, certain sounds from your radiator are perfectly normal. 

For instance, clicking and ticking noises from the radiator happen all the time and are usually signs that the metal is expanding or contracting as part of the natural heating process. Sometimes you may also hear these types of sounds coming from under your floorboards which is more than likely just your radiator’s pipes doing the same thing.

However, it is still important to pay careful attention to the type of sounds your radiator is making. 

Crackling, fizzing, banging and bubbling sounds normally mean that there is some kind of problem that needs to be investigated. 

By remaining vigilant and paying attention to the noises your radiator makes, you can avoid a serious fault from occurring.    


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