I have just done a complete bathroom refit and it has generally been a success.
I do have one small issue though, and hoped someone might have a suggestion.
When I fitted the new bath, I had to change the plumbing to get it to fit the old waste outlet (due to the new position of the bath plughole).
The bath drained fine.
When I connected the sink waste, which shares the same waste outlet pipe, the bath started to drain slowly. Disconnect the sink bottle trap and the bath drains quickly again.
Since it seems to be something to do with the air flow into the sink waste pipe, I replaced the sink bottle trap with an 'anti-syphon' one.
This doesn't seem to have had much effect tho.
Can anyone suggest any solution?