Up until recent history, pilot lights were used in nearly every furnace to ignite the burners when a heating cycle begins. A pilot light is a small flame that burns continuously inside of your furnace whether it is running or not.
03-09-2019· Thanks for your responses. It is a Baxi Solo RS 2 boiler. Perhaps I was just ignorant to the pilot light being on. Sorry if the second point seems contradictory but to explain - the whistling only begins after the boiler has been on for a long period of time but it ceases temporarily when the boiler is actively burning gas, i.e. it only whistles when the hot water is pumping through the boiler system.
The thermocouple is the little metal rod that the pilot light flame plays on. The flame warms it up, a semiconductor junction inside the tip of the rod generates a voltage and causes a current to flow in a coil in the gas control valve. This coil generates a magnetic field which holds a spring-loaded valve open, supplying gas to the pilot light.
Boiler pilot lights were a good thing at the time. Like all things today become outdated. Most boiler manufactures have not produced a pilot light type of boiler now for over 15 years. So if your boiler is of this type then now is a good time to think about replacing with a new energy efficient boiler.
A pilot light is a small gas flame, usually natural gas or liquefied petroleum gas, which serves as an ignition source for a more powerful gas burner. Originally, a pilot light was kept permanently alight; however, this is wasteful of gas.
The gas is lit by a permanent pilot light, and turned on and off to control the boiler temperature by a thermostat with a sensor inside the heat exchanger. The ‘multi-function gas valve’ supervises the pilot flame using a thermocouple, turns the gas on and off to the main burner, and regulates the gas pressure to the burner.