Minimum Clearances when drilling an overflow

[ensquire]

Originally Posted by lastlight

I think you need a few more inches between them otherwise the primary is going to be sucking air from the surface when it starts creating a vortex.

Sorry Lastlight not quite following you here. When I was running it to test it, there was no noise, great siphon. The 1" drain has about 2" of 1 1/2" pipe sticking up and the 1/2 emerg rises to about halfway up the overflow teeth. there was no vortex at all, ran great like that for 3 days. Only problem was I used a ball valve instead of a gate on the drain which I will change. Problem came when I blocked main and the emergency line seemed a little small.
So are you saying that if I increase the secondary emerg drain size it might cause the siphon to not work the same ?? Presently the two lines are only 1 5/8 apart. A picture would help and I can't post one till tomorrow to clarify this.

Originally Posted by lastlight

Not sure if this is an external or internal overflow but remember you can always drill a new hole from the side of an external or through the back wall into your internal and have it higher up so the top of the elbow/emergency is just below your overflow level. My water drops 1/2" into my overflow box since the water line is controlled by my emergency which always has a slight trickle going into it .

It's an internal ..Never thought about this possiblity, definately a workable solution if the other doesn't

Thanks and sorry for needing the clarifacation.