armando would this work for my overflow.

[CiroFuentes22]

i wanted to know if this would work for my drain pipe. i only have 1 hole for the drain and one for the return so i cant use the one for the return for my backup. i put a "t" after the "gate valve" wit the backup drain pipe a little bit higher than the main drain pipe just incase. Armondo was showing me about a way to eliminate the bubbles from the return by useing both holes but i only can use one of the hole so i was thinking that this might work.

 

[Abengochea]

no actually it wont work for 2 reasons. first it would be very hard to stick ur hand in the overflow box to adjust the valve. Secondly in adding the second pipe to the original, u are allowing air to get back into the plumbing. The idea is to control the first pipe to keep it submerged and not allow any air in it