Why is my boiler whistling?

Imagine your boiler making a whistling sound. Now imagine hearing this sound continuously for hours. This would probably not be as good as it looks like.

You might be wondering as to why is my boiler whistling? Boilers are something that are most of the time taken for granted for as long as it is working properly, none of us would even mind to think about its maintenance. However, things can turn off from time to time, and the first sign that comes to the notice is an unfamiliar or unnoticed noise.

When your boiler begins to make noises, you should understand that it needs to be looked upon as there is something that is interfering with the operation of the system.

Why is my boiler whistling?

From our understanding of boilers there can be 3 main problems that happen to be the reasons of your system making a whistling noise.

The whistling sound from a system can either be an outcome of kettling or the trapped air within the system.

1. Kettling is something which occurs as a result of the lime scale buildup in the system that eventually creates bubbles and leads to the occurrence of ‘hot spots’.  These hot spots are what causes loud noise and needs to be treated with a solution in order to clear the lime scale blockage.
2. The other reason could probably be the air that gets trapped in your system and simply needs to be released out. While if the problem is that of the air being trapped then it can simply be repaired by releasing the trapped air from the system through the process of bleeding.
3. However, this sound of whistling can also be a cause of the loss of water pressure or a blockage. It might be the case in which there isn’t enough water flowing through the system due to the low pressure. That is why your boiler is whistling when hot water is on. You need to look at the pressure gauge to check the pressure. If you find the pressure to be lower than one bar, then you would need to repressurise the system.

Now that you know about why is my boiler whistling, you might be wondering about how would you stop the boiler from making such noises. 

1. Check the water pressure- If the water pressure is too low then it might be the culprit of your whistling noise. Have a look at the pressure gauge that is located in the area where the pipes are connected to the boiler, in order to check on the pressure of water in your boiler. If the pressure is below one bar then you would need to top up the pressure and increase it until it gets restored to the correct level. For this you might need to consult the manual or a professional help.
2. Bleed the system- In many cases the sound from the boiler is a result of the air trapped in the system that needs to be released out. That is probably when you would need to bleed the system that can be done in a few simple steps-
3. Fully open all radiator thermostats and run the heating at full temperature for 10-15 minutes with all radiators on
4. Now simply turn the circulation pump off and wait until the radiators get cooled. This would require minimum of 30-60 minutes.
5. Bleed the radiator that is located near the boiler using a bleed key or a screwdriver until the water comes out.
6. Repeat this for each radiator
7. Turn on the boiler and check the water pressure and you are done with process.                               

While on a clear note these are not the only issues that cause a whistling sound in your boiler but these are some of the most common reasons that happen to disturb your peace of mind.