bathroom extractor

[geome]

I am fitting a bathroom extractor fan the bathroom has an existing vent via an outside airbrick if I remove the vent can I put my new 4inch ducting upto the old airbrick or will this restrict the airflow.
Would it be better to cut a hole in the airbrick and put the ducting through it with an outside backdraft shutter.

 

[endecotp]

It will restrict the airflow, but perhaps not by too much. Personally I'd try it and see.

 

[foxhole]

You are putting 4" out thru 10" vent? will not restrict flow.

 

[geome]

Yes but the 10 inch brick is not a straight through outlet it's made up of a series of holes which in total might not
Add up to the volume of the 4 inch pipe.

 

[Doggit]

If it was a toilet, there wouldn't be an issue, but being a bathroom, you're extracting moisture laden air that is going to condense on to the cold airbrick, and eventually cause a problem. Use tubing and an outside shutter, and remember to have a slight downward slope towards the outside for the water to drip away.

 

[foxhole]

Had the same thing on my bathroom for 20 years , never a problem.