Quietening In-Line fan vent noise

[caveman2]

I have fitted a Manrose in-line fan in my loft for my bathroom. As previously mentioned by others the fan itself is very quiet.
However the noise from the extraction grill is far louder than I imagined. Although it is reassuring to hear the power of the fan drawing air through the vent I would like to quieten it if I can. I appreciate that I can reduce the speed setting from the default fast (the highest of the three options) but is there another way?

 

[JohnD]

your grill may be too small or obstructing airflow. What is the size? Please show a pic.

If you take the grill off and let the duct suck, is it quiet?

 

[caveman2]

https://www.powerdiscount.co.uk/manrose-2100-internal-circular-wall-grille-4quot-100mm-4481-p.asp

I have removed the grill section and it is no quieter as a 100mm hole

 

[Nige F]

Is it possible to move the fan further away from the suction grill and nearer to the exit grill .

 

[caveman2]

Is it possible to move the fan further away from the suction grill and nearer to the exit grill .

Yes, will that help and if yes, will it affect it's suction power?

 

[Nige F]

Not AFAIK because it sucks but also pushes the air. If you see what I mean As to noise It should help but if not you may be able to get some noise attenuation tube. Worth a try.

 

[John D v2.0]

If you have space you could make a box and connect the fan suction and bathroom pipe to it. The box would be made of wood, well sealed and insulated and I suppose 300mm each direction. That would prevent the noise.
Not sure how to prevent the condensation risk completely, perhaps I should have suggested made of plastic and drained.

 

[EFLImpudence]

Is the fan really necessary?

 

[SimonH2]

What sort of ducting have you used - flexible or rigid ? Flexible ducts can be quieter but restrict airflow more, rigid ducts are free-er flowing but also act duct any noise from the fan (both airborne and mechanical) over long distances.

 

[ban-all-sheds]

I have fitted a Manrose in-line fan in my loft for my bathroom. As previously mentioned by others the fan itself is very quiet.
However the noise from the extraction grill is far louder than I imagined. Although it is reassuring to hear the power of the fan drawing air through the vent I would like to quieten it if I can.

It's so loud that it's unacceptable to you when you're under the shower?

 

[John D v2.0]

It's so loud that it's unacceptable to you when you're under the shower?

That would be a reasonable summary of his post. Although he doesn't specifically state that it's only on when he's showering.

 

[ban-all-sheds]

True, he doesn't state that.

But surely if not showering then a lower speed might be OK?

 

[caveman2]

What sort of ducting have you used - flexible or rigid ? Flexible ducts can be quieter but restrict airflow more, rigid ducts are free-er flowing but also act duct any noise from the fan (both airborne and mechanical) over long distances.

I have flexible ducting distances bathroom ceiling to fan 4ft and fan to soffit 6ft. Extending distance from bathroom doesn't improve noise.

It's so loud that it's unacceptable to you when you're under the shower?

Not while under shower but the 15 minutes spent in the bathroom afterwards. Comparing my fan noise to my sons makes mine noisy. His was fitted during a bathroom installation and whilst looking the same as mine. His is 23W 2 speed and mine is 25w 3 speed. His is barely audible while mine is very obvious.
I have yet to try lowering it to medium setting whilst searching for other ideas.

 

[SimonH2]

I have yet to try lowering it to medium setting whilst searching for other ideas.

I would try that - fan speed makes a very big difference to noise levels.