I have a shower on the second floor of a two story house that is draining in a weird way. The shower will start to fill, then all of a sudden drains and for the rest of the shower it drains fine.
I suspect there is a partially or fully blocked drain but eventually a siphon is formed somewhere else that then drains the shower. But if a siphon is formed I can’t figure out why it doesn’t fill up again and then repeat the process during the same shower. It does seem to repeat at the start of each daily shower.
So what do I do about this? Pour liquid plumber down the drain and hope it breaks up whatever is down there?
I can call a plumber, but I’d prefer to have some idea of what might be going on.
Have you tried opening and closing the drain a few times. It could be part of the drain mechanism in the way that eventually gets pushed back into the open position and stays there as long as water is moving past it.
You could also try getting one of the zip-it type drain openers and see if you can pull anything out of it.
How does a vent problem for the shower make it partially fill, then suddenly drain? I’m assuming the pressure in the drain lines increases until such a point that the sink is used as the vent for the shower, but I can’t quite picture how all that works.
How does a plugged shower vent prevent it from draining?
The air in the pipe below the shower water has nowhere to go. So the shower water cannot easily drain. If the pressure builds up enough, then the air will start forcing itself out thru another pipe’s trap or some such. Once that starts flowing, then the shower can drain.
Well anything is possible, but many of homes in this category would have a autovent device, which as long as the seal doesn’t fail preforms like a standard vent. I have not heard of housing coming more stripped then that just due to code. It’s also a easy and cheap fix if one can access the drain line and has a bit of room.
