"Commander Kinsey" wrote in message
news
p.0jd0jv0pwdg98l@glass...
On Mon, 20 Apr 2020 19:27:43 +0100, ARW
wrote:
On 19/04/2020 20:46, charles wrote:
In article op.0jb2xvjcwdg98l@glass,
Commander Kinsey wrote:
Why did drainpipes used to have a box on the wall, some sort of
overflow if blocked? See link below for an example photo.
https://www.dropbox.com/s/1jry8zas14bmivc/box.jpg?dl=0
I still have them. It provides an air break to prevent feedback.
There is some suggestion on certain web sites that it is to increase
flow rate.
How would that happen?
Stops a big ait space forming in a long vertical pipe.