Have i strangled my bathroom extrator fan

[Lower]

I have a Xpelair DT100 fan fitted in our bathroom. Its an axial fan rated at 76m3 per hour.

It came with a multi flap back draft shutter that rattled noisily in the wind, so i replaced the back draft shutter with a cowl vent:

Extraction from the bathroom doesn't seem great. I used a smoke match to watch how effective the extraction is and it barely moved it.

What i don't know is whether the fan i've got doesn't move enough air or whether i've strangled it by fitting this vent that turns the airflow through 90 degrees and used the airflow to keep the flap open.

Bathroom is pretty small, approx 2.5x 2m.

Comments appreciated.

 

[wingcoax]

You will not move much air with that fan, your external cover will not make much difference.

 

[kevplumb]

it may well be a pump problem

 

[Lower]

Its an axial fan so turning the air through 90 degrees won't help and the fan pressure also has to hold a single flap open.

Having looked at it again last night the fan is barely pulling any air at all.

I think i'm going to try changing the backdraft shutter back to what we had before and then find a way to quieten down the movement of the blades.

Any suggestions on how i can make a multi blade shutter quieter?

 

[JohnD]

the cowl is fine but you need a better fan.

Centrifigal fans are generally quieter and more powerful.

 

[ambi]

Lower,
Narrow things down, take backdarught shutter off and operate with no b/d/shutter to see if air extraction iis adequate! You will have a better idea of the state of play then!

 

[Lower]

I'm limited on the fan is it is a through wall fan with a 6" duct in a recently fully tiled bathroom so i really don't want to be making bigger holes etc.

Whilst i understand that centrifugal fans are better (higher pressure) they are also a lot more bulky so i really want to avoid having to fit one.

I didn't really look at the airflow with the older, easier flowing back draft shutter fitted so i guess the next step is to remove the restriction and see how much effect it has. .

 

[JohnD]

your duct is already big enough.

Although some in-loft centrifugals are big, the wall-mount ones are not obtrusive. They tend to be shield-shaped rather than round.

If you have a 6" duct you could even fit a 6" fan (assuming your currently have a little 4" one)

 

[TicklyT]

The other necessity to get a fan to work is ventilation allowing air into the room. If air can't get in, there's nothing for the fan to extract.

Monitor the airflow from the fan with the window / door open and closed.