the_constructor wrote:
Just out of curiosity, are 12V timer fans noisier than 240V fans....?

I got a 12V fan and my neighbour nearly jumps out of her skin when it is
switched on.

I installed it correctly a few months ago but after a week I disconnected
it.

It must be bad though because I can hear it downstairs through 3 closed
doors.

The fan is from Screwfix....

Check out the rotational speed. For a given airflow, the DC fan solution
of a higher rotational speed is cheaper than the ac fan solution of
redesigned fan blades. Unfortunately, it tends to also be a noisier
solution. DC fans tend to have higher starting torques, so the onset of
the noise is much more sudden, too.

One of the advantages of DC fans is that it is usually very easy to
decrease the fan speed and hence greatly reduce the noise. Simply by
lowering the DC voltage. Even a small reduction in voltage (eg a couple
of diodes in series with the supply) can make a great difference.

--
Sue