1)Why used "T-fitting" instead of "Y-fitting"? 2) what about air pressure drop? After two similar sized pipe connections branch, why used the same sized header pipe? 3) Why not maintained the pipe slope for vent air? 4) Why were PVC pipes used? If a short circuit occurs, the plastic pipe can burn very easily and the fire can spread to the entire roof.
PVC pipes might be cheaper than aluminium vents. Good point on Y fitting. Air pressure drop between which points. Will slope make difference for air flow?
