What kind of air vent should I get for this run?

melo

I currently have an air vent as shown on the photo.

It's loud, hisses, and I think even lets out steam. I don't know where this valve came from but it doesn't do a good job. So I have the same one on my second floor, please look at Issue #2 on my diagram. I want to put a valve on top of that which will let some air out and then close up as much as possible to stop letting more air or STEAM out (unsure if this is possible, I'm an electrical guy, don't hurt me).

Any help would be much appreciate from this awesome community.

ethicalpaul

Here's what I would try