Inefficient bathroom extractor

[DaveSCH]

My bathroom extractor doesn't seem to work too well. Same type as in ensuite which works well. Bathroom one, we need window open wide but still steam/ condensation builds up. Now have mould dots above bath, house only 18 months old. Thought defective fan but been in loft and looked in flexible pipe at points along to where it connects to the outside via a fitting in the roof tiles. With fan turned on I feel strong rush of air going through the flexi pipe towards roof outlet. So fan and internal pipe okay. The outlet panel feels like a grill but can't feel any kind of gaps to allow air through. Can't get into a position to see it properly. Also can't get a view of the tile fixture from the outside, appears flat, same colour as reddy brown tiles. The connector is braas system. Any ideas? Dave

 

[Porque223]

One standard for bathrooms is 8 Air Changes per Hour so from the fan's CFM rating and the bathroom volume you can check this.
You may want to undercut the bathroom door to allow replacement air.

If you have a huge bag of very thin plastic that you can estimate the volume of, tape the air filled bag to the fan inlet, switch it on and time it. I saw a video where they compared this method to commercial airflow instruments and it didn't do that bad.

The simple method is to see if a piece of paper holds to the grill and drops when the fan is switched off.

 

[foxhole]

If it has any type of grill on the outlet it will become choked with fluff etc and need cleaning, I have my fans connected to ceiling mounted sensor so they run whenever the room is occupied, far more effecient than just turning it on when you remember.

 

[DaveSCH]

Thanks porque223 and foxhole. The fan easily holds a piece of paper and as I feel good airflow in the pipe, I guess I need to get into the outlet to check for blockages. Can't feel anything but very difficult to get in. Dave