When you boil a kettle the water inside begins to heated up to one neutered degrees centigrade. Some of the water inside becomes so hot that it turns to steam and escapes through the top. Older kettles that relied on gas hobs to heat the water had an indigouns spout that would whistle to tell you that the optimum boiling temperature has been reached. The steam would whistle through the spout quite loudly. If it stopped then there was every chance the kettle would boil dry and you were going to lose the kettle. Modern kettles have a cut off switch. To protect the environment this boiling time has been greatly reduced and the kettle cuts out very early.
However if this kind of noise is coming from the boiler or the radiators it is not an ideal situation. It means that some air becomes trapped in the pipes and it will explain where your radiators are not getting warm even when you have them on full blast. It might be that you will need to call a Boiler Repair Gloucester based firm to fix the issue but you could try and bleed the radiators first.
This is the only thing that you can try yourself. Do not attempt to fix the boiler that is very specialist work. All you have to do is release the valve on the top right hand side of the radiator to let out the air. Once the air is out it should let the water flow again and not start that whistling sound anymore. If symptoms persist then click on the link.