Monoflow, Venturi, Scoop Tees

I was reading one of your posts about radiators not heating up. I understand the purging of the air. Thanks for giving me the idea to utilize a ball valve to force the flow to complete the loop.

I am a DIY type not a professional. I started replacing some of the old Scoop Tees on my heating system because some had aged and started to separate. I have a 1" loop in the basement with tees supply and return. I started to replace those tees that has separated and will give me problem next heating season. I have not refilled the system to check it but after reading a post from 2011 I may have to revisit the Tees that I have already replaced. I utilized the B&G monoflow tee and I placed it in the direction of the old scoop tee and they were all on the supply side is this wrong? I believe the post indicated that it should be on the return side. Is this because it restricts the amount of flow at the return to allow for the flow up to the radiator?  The current system had two scoop tees facing opposite directions and I followed the same pattern. I don't know if it mattered but the home has three levels and a basement.