Double Y Elbow Issues
The Double Y fitting for Central Vacuum Systems can create potential issues that prevent your system from operating at its full potential.
Why we do not recommend using the Double Y fitting
Debris coming from above will pile up below because not all of it makes the left turn to the vacuum unit. Use the alternate fitting setup shown on the left to prevent clogging issues.
Imagine a pipe that needs to split into two opposite directions, directly up and directly down. The problem with the double Y shown on the right is that debris coming down from above, trying to make the turn to the left to go past the fitting and into the pipe below. If inlets on the lower line are not used often, then the pipe will build up with debris and clog the system. Although the setup above might take a few extra fittings, you can see that all the debris will properly flow to the unit when using the setup on the left.
Debris coming from the left or right will pile up on the opposite side possibly causing clogs. Use the alternate fitting setup shown on the left to prevent clogging issues.
Picture the double Y being used where pipes are running horizontally. There would be one pipe coming from the left and one from the right. They want to flow toward the bottom of the picture. Again, it is possible for debris coming from either the left or right to carry themselves through the air stream and centrifugal force would push the debris into the opposite dead-air of the line that is in direct flow rather than making the turn toward the lower part of the picture toward where the power unit is located. This would lead to a clog if the one side did not regulary have air passing through it.