OK...
This is my oldest daughter's home recently purchased (1952 build) and is has many nightmare issues. It is about 100 miles away and I cannot get out there to help much, plus I am old and feeble...
She had a handyman install a new sink, faucet and DW, and straightened out some of the P-Trap fiasco. But there is still a vent problem I think. There is no sanitary tee and vent pipe behind the wall @ the juncture, only a downturn.
Can this be vented somewhere else or is it illegal (she was complaining earlier of odor with the S-Trap configuration).
(I've all ready explained the DW drain hose to the air gap has to have the loop straightened).
Now this brings up another question...
I am thinking ...
... that a DW discharge hose should have an anti-drain back valve (such as used in a sump pump) to keep excess water pressure (water left in discharge line) off the DW discharge valve when idle and at first discharge to allow a smaller load on the pump... ???
Yes, I haven't much to do...
ANOTHER REALIZATION-
It is still an S-Trap as configured, correct?