I have a plumbing system just like this picture in my house:
The water comes from the water tank that is on the top of the house. In this particular situation shown in the picture, the water goes to the first floor, enters in a forked connection and goes to the tap 2, in the first floor, and to the tap 1, in the second floor. This is a project failure, the connection should be in the second floor, due to this, I'm having problems with air inside the tube that links the tap 1 with the connection. I think the air is getting into the tube by tap 1.
Tap 2 is working nice. Is not always I have tap 1 not working. When I take the air off the tube, it comes back to work, but, by the time passing, 6 months approximately, tap 1 stops flowing water.
How I can avoid this situation without change the tube system? I thought about a retention valve connected to the tap 1, would it work?