Usually there is a gap around the washer hose that lets enough air in that it does not need a vent.
Yes, a washer drain typically requires a vent for proper functioning to prevent airlock and ensure proper drainage.
There is usually some space around the drain hose where it goes into the drain. This usually allows enough air to get in that it is not a problem. If the washer hose is connected to the drain tight, then yes, there needs to be a vent above that connection. There may already be one above the drain if you follow it up. Most washer drains are fairly close to the main stack which allow for venting. The only question is, Does the washer drain alright? If so, don't worry about it.
To get water to it, and to have it drain
Should be individually vented
Without knowing the layout or type of drain pipe and location, it is impossible to give a good answer. Drill a hole in the floor and run the drain with PVC. Drains should fall 1/8 to 1/4 of an inch for every foot of distance. Horizontal distance. There may be a drain line that is closer to the first floor location that you can tap into. Washer drain does not need a vent, it gets it's venting around the washer hose.
A washing machine drain needs a vent to prevent air pressure buildup, which can cause slow drainage or backups in the system. The vent allows air to enter the drain pipe, helping water flow smoothly and efficiently.
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.
The vent is behind the overflow cap where you close the drain. --Without a vent, the water would drain very slow.
The condensate drain on the a-coil should have a trap and the trap should be vented for proper operation . The vent should rise above the top edge of the drain pan in the unit. Their should be a capped clean out before the vent.
A shower drain needs a vent to prevent air pressure buildup in the plumbing system, which can cause slow drainage or gurgling noises. The vent allows air to enter the system, equalizing pressure and helping water flow smoothly down the drain.
To fix a clogged drain washer in your sink, you can try using a plunger to dislodge the blockage. If that doesn't work, you can use a drain snake or a mixture of baking soda and vinegar to break up the clog. If the clog persists, you may need to remove the drain washer and clean it manually.