Unidentified pipe

I need some help identifying a pipe in my boiler system. I have a 30 year old Weil MacClain boiler system (2 actually, as this is a duplex). I have a pipe that extends into the ceiling of my basement and presumably runs up to the upper unit somewhere. The other end of the pipe heads across the ceiling to an area near my basement floor drain where the pipe is open (uncapped). I cannot detect any liquid coming out of it (but it's summer). There is another pipe that T's down to another pipe that leads to the main boiler pipes in the lower unit. I might have assumed it was my condensate pipe but shouldn't there be two (one for each boiler)? If it is the condensate pipe, shouldn't it drain to the outside? I'd like to demo out or re-route this to remodel my laundry. Any idea what this is?

pictures paint many words and helps.

I'm not sure you can tell much from the pics. but here are both ends that I can see.

It’s an overflow for a tank or system

the copper pipe i would guess is a blow off pipe from the boilers?