Yeah ,the sink "trap" is always filled with water to block the stink and if you are pushing that water out with home air pressure ,you got a problem-won't happen.
I solved the cooling problems when I did my remodel
I installed 4 of them with auto sun shades.
they work by remote and you can open them as much as you like and the hot air that is naturally at the highest point at your ceiling rapidly escapes and if you have a window open (in my case downstairs), you create a suction or breeze that continues until the house either cools or until you close the skylite.
They also close automatically when it rains
They can also be installed if you have an attic by using a box up to the roof.
"FOR THE FIRST TIME IN MY LIFE ,I AM PROUD OF MY COUNTRY"...2008 M.O.