Moved into a house with older plumbing that my in-laws own. Thier handyman didn't know what this fixture is. It has two holes, one on each side and water bubbles out of the holes. It is tapped into a water supply line and the bottom pipe goes into the basement floor. What is this?
FYI Districtwolf10, a trap primer just sends an occasional small supply of water into a trap to keep it from drying out, which keeps the sewer gases contained.
I’m not certain, but I think when the washing machine uses cold water, the pressure drop in the cold supply pipe activates the trap primer valve, to let a little water out down that copper line, into the floor trap.