Location of outlet for inline bathroom fan?

[Possom]

If I have a Vent Axia inline fan installed in the loft above the bathroom, I could relatively easily have it vented via expanding pipe across the attic until above the bedroom and out there (location 2). It means only a ladder is required to cut the hole.

However, a shorter route, meaning the expanding tube is *not* positioned above the bedroom means having to construct scaffolding to try and get to the location to cut the hole (location 1).
The additional distance is about 2.5m

Do you think the shorter route will make any particular difference to noise emitted from the tubing? I'm not sure how noisy these things are once activated, if they're not particularly noisy then it may not make any difference.

Thanks.

 

[oldbutnotdead]

The fan itself will be the noisy thing. Plus if it is the usual minimum airflow as required by building regs it'll struggle to push air through a longish duct of any type. Better off using rigid pipe where you can (reduces drag within the pipe which thus reduces any noise from airflow)

 

[Possom]

The fan itself will be the noisy thing. Plus if it is the usual minimum airflow as required by building regs it'll struggle to push air through a longish duct of any type.

Vent-Axia ACM100T inline fan:
Extraction Rate 220m³/hr
Noise Level 22dBA at 3m


Is this the minimum airflow which you refer to, or above?

What would you prefer to be max the duct out at in terms of length?

 

[flameport]

That fan is far in excess of the minimum extract requirements - which is a good thing as the minimum is so low that it will have no real effect on anything.

The noise level is very low, doubtful if you could hear it at all outside at ground level.

 

[Possom]

That fan is far in excess of the minimum extract requirements - which is a good thing as the minimum is so low that it will have no real effect on anything.

The noise level is very low, doubtful if you could hear it at all outside at ground level.

What I was wondering is if the outlet is positioned as location (2) then that means the tubing is over the bedroom and so is the outlet, and so would this produce more noise for any occupant below. Though it sounds as if it won't make much particular difference.

 

[JohnD]

the vented inline fans are generally significantly quieter than the cheap builders fans, as well as more powerful.

Furthermore it is not in the room, but up in the loft.

You can mount it on a piece of ply, isolated with thick carpet or rubber mat, to deaden the sound still more.

You will be using insulated duct, or wrapping it in mineral wool quilt, to prevent condensation, which will also muffle noise.

 

[Possom]

or wrapping it in mineral wool quilt, to prevent condensation, which will also muffle noise.

I didn't know that they can be wrapped in mineral wool quilt to prevent condensation?

By "mineral wool" do you mean Rockwool loft insulation? (There is some left over from when the loft was insulated).

 

[JohnD]

yes.

the ducts are full of steamy air, and the loft is cold, so unless insulated, the ducts are prone to condensation.

Slope them slightly down towards the vents outside. Rigid ducts are less of a problem than flexible, which can trap water and fluff.

 

[Tigercubrider]

I have an inline fan in my flatroofed extension and it's pretty quiet
I think your query is whether the outlet itself is noisy? So running it over a bedroom may disturb someone?

Imho just mount the fan on neoprene or something so that the entire loft doesn't vibrate and get it high enough so that any condensation naturally drains out . You can insulate the output duct for warmth but it shouldn't actually make much noise

Choose the vent output carefully as the one in my kitchen rattles. You may be better to just have a hood and install a weighted back draught stopper in the loft

 

[JohnD]

I find the cowl vents are mostly quiet. They just have one big flap

http://www.screwfix.com/p/manrose-cowl-vent-brown-100-x-100mm/14789

unlike the sort which are like little venetian blinds, and rattle constantly until they fall off in moderate winds

 

[Possom]

I think your query is whether the outlet itself is noisy?

Yes.

I purchased an external fixed grille in the style shown below (in black).

 

[dobby1]

Have you calculated the air volume of the bathroom before selecting an appropriate fan ? You will also need to factor in any bends and ducting material. Using flexible duct is the worst possible decision you can make. It will create too much turbulence, increases chances of air condensation and thus trickling back into the bathroom, and significantly reduces airflow.

Also, remember that cutting out a 100mm+ hole on a ladder is no easy task. The last I had to cut through a brick/block wall, it took me at least an hour with a core drill, and a heavy hammer drill to at that, not pleasant.

The outlet noise itself isn't as loud as the fan itself, although again it depends on how much air you are pushing. Generally speaking, using larger ducting will reduce any noise being emitted by the outlet.

 

[Possom]

Have you calculated the air volume of the bathroom before selecting an appropriate fan ?

I haven't calculated this, though it is a very small bathroom 1.7m x 1.4m

Extraction Rate 220m³/hr

Also, remember that cutting out a 100mm+ hole on a ladder is no easy task. The last I had to cut through a brick/block wall, it took me at least an hour with a core drill, and a heavy hammer drill to at that, not pleasant.

It would be through timber (under the guttering).

 

[JohnD]

soffit?

 

[flameport]

would this produce more noise for any occupant below. Though it sounds as if it won't make much particular difference.

22dBA is about as quiet as normal things get.
This chart: http://www.dot.ca.gov/dist2/projects/sixer/loud.pdf shows dBA for various common situations.