Tee or Elbow?

[shaken-n-stirred]

If I have a 3 inch drain line coming from a toilet running horizontally and then need to drop it down the wall with a vent running directly up from there should I or can I :

1. Use a 3 inch 90 (elbow) with a 2 inch hole running to the vertical for the vnet? (is that a low heel ... blah blah?) or do I need to use a 3x3x3 sanitee with the 3 inch vertical used as the vent?

 

[ExtraMilePlumbing]

Low heel is preffered

 

[shaken-n-stirred]

Why is that preferred?

 

[frodo]

USE A 3'' SAN TEE WITH A 3X2 BUSHING in the top of it.

 

[ExtraMilePlumbing]

Because it's all in one , less fittings , less chance of leaks