Un-capped vent...does it need a cap ?

Does this vent need to be capped?



Where does the water go when it rains?

If it is a trap vent…No. Anything else Yes.

Should probably be flashed better though.

David it looks like plumbing vent. Since traps stop the gasses from coming into the house, vents are installed to give those gasses a place to go. Otherwise, pressure would build up in the system. When it rains, the water goes into the plumber and drains like any other water. At least that’s my understanding of how it all works. Someone might be able to elaborate more.

And that it is.


Trap (as in plumbing) vent… NO. Rain entering drains to sewer.

Anything else (as in ceiling fan exhaust, hvac, etc.)… YES. Rain entering potentially damages unit.

Don’t be so inclusive Mr Jonas:p the 90% furnace flues have a drain at the bottom of the stack:D

Don’t be so inclusive Mr. Bottger:p… they are not always installed… or working as intended:D


Thanks everyone for the response…

Yes it does allow the gasses to escape. However, the other purpose of the vent is to let air INTO the drain system. Since waste water flows by gravity, it would not work if air could not get in.

But you could always cap it and sit back and watch the fun. Things get boring, sometimes,

Thanks man.