New non-vented sink/vanity install drains slow

I replaced our old "vented" vanities with Euro style non-vented sinks. I understand the vent pipe through the roof, but have not checked that...yet. I find it odd that both are draining slow. The 2nd bath I installed this vanity, I actually ran the water hose into the 1-1/2 Galv. Pipe with the balloon for about an hour without a problem. I can't image that the vent pipe would be plugged, although the house is 50 years old, but I've had both drains cleaned about a year ago.

I called a rooter company and the technician stated that if the drain was plugged that the water would not go down,I concur from what I know.

I noticed there was another person who had a similar issue ,but his vent pipe was capped off in the attic, mine goes through the roof, just not sure if some obstruction exist, but I have this problem on both NEW sinks.

The 1s bath, has a pop up drain. I'm planning on removing the popup and testing if that helps. The 2nd has the flat chrome /strainer type cover with approx 15 drain holes. In the second, I can even see the water coagulate in that cover/drain plate after the water drains. In other word, it appears as the water is defying gravity and like the other gentemen stated ...."possible airlock" ?

I like to see (like my other sinks) where the gravity "pulls" the water down...not seeing that in the bath basins after new sinks. The sinks before, drained somewhat slow as well, but the water did not become standing.


Suggestions are appreciate (unless you suggest repipe or sell the house ;-)) LOL

Tia !

Mark