Faulty vent?

stilts

Have a heat riser/pipe in a small bathroom with what looks like a 3/4” vent at the stop. When the heat runs the vent is very loud and seems to be venting because there’s water left behind on the window frame next to it, my question though is this the vent working properly or needs to be changed? I’m afraid of not only paint peeling but someone getting hot steam secreted on them. Should this pipe not be vented and just act like a heat pipe or should the vent be changed to one that is closed? If so what vent should be used? 

bburd

That vent looks very old, and it may well have failed. It is supposed to vent air and close when steam reaches it.

Steam pressure in residential heating should be 2 psi or less. Excess pressure can damage vents and prevent them from closing normally. High pressure will also tend to cause noisy venting. I suspect your steam pressure is too high. This can be caused by an incorrectly set pressuretrol or a clogged connection between the pressuretrol and the boiler.

if you have access to the boiler, please take some pictures of the boiler, its  surrounding piping and a close-up of the pressuretrol which is a 4"x4", usually gray box somewhere near the top of the boiler.