Presssuretrol does not turn off boiler fire at 4-5 psi

When you are setting up multiple vents on your main or the end of the dry return you have to have some combinations of tees and elbows. If you went up to a tee and had a branch on either side with vents on either side of the tee you can't get a downward pitch on both branches. If you go up to an elbow and only have one longer branch with multiple tees and an elbow pointing upward to accept your vents, that gives you the opportunity to give the entire branch a downward pitch for condensate to drain away from the vents.