BAD venting causing negative pressure / back siphoning
This is not a venting problem. You have a possible blockage. Get a plumber to check your sewer lines. They may need to be cleaned out.
Sounds like a venting problem. The washer is trying to push the water down the drain and the tub is an easier route. When it stops pumping, the washer drain become the vent and lets the air escape. You can try some drain cleaner in the tub and the washer drains. This may open it enough to help.
It is not possible to prevent the customer from stop venting in any case.
First, research the venting codes in your area. First, research the venting codes in your area.
Should not be necessary. Venting of methane on an LNG vessel should be a very rare event. Prudent operators would avoid unnecessary venting. Any venting, if necessary, should be very warm gas.
That depends on the volume/size of the tub in question. A "tub" could be a butter tub, a mash tub a bath-tub etc.
Bad venting
"Standard tub" is too vague. More information is needed, especially what the 'tub' is used for? Tub of icecream? Tub of lard? Bathtub? etc.
Cast Iron is great for drainage and steel piping is good for venting (galvanized , or wrought iron or yalloy ) for venting
No, this microwave can be mounted right underneath the cabinet without any venting space required.
lub tub lub tub lub tub....