Combi boiler making noise constantly?

benkil

Hi,

We are first time buyers and just moved into a new build property and im not sure the boiler is working properly but i could be wrong!

Basically the boiler makes a humming noise constantly.

When I turn the hot tap on it makes the noise I would expect as its heating the water but then it just goes back to making a quieter humming noise.

Are combi boilers supposed to be silent when they are not heating water/radiators?

Thanks

Tom99

Most have a small internal water tank that can be pre-heated so that you get instant hot water, so it could be the boiler firing for that reason. You can turn that option off if you want to.
Also on the CH part most will have a pump overrun so even after the boiler has been turned off the pump will run for a short while to extract all the residual heat from the boiler.
When it next makes the noise turn off the main power supply switch and see if the noise stops.

Mr.Generous

Wonder if the fan is running on.

benkil

Ive turned off the pre heat option and even when i turn my thermostat down to the lowest temp possible and dont run any hot water it still hums. Its constant, never changes.

Only way it changes is if i run hot water.

JimmyChanga

Are combi boilers supposed to be silent when they are not heating water/radiators?

Depending on the boiler. Some will still have the fan running constantly at a lower speed even when no demand.
Otherwise old power supply on the PCB can also start humming.

Apodemus

It’s not the CH pump itself that you are hearing is it? It will presumably run while the central heating is switched on, but the boiler will only fire-up when the returning water is below a threshold temperature.

southcoastrgi

What boiler is it ?