Radiant Loop

Gordy

I have a loop configuration in my 50's ceiling radiant home that has me kind of baffled as to why it was done in such away. The loop has one supply 1/2" which T's off up in the wall somewhere and supplys three adjoining rooms with 3/8" and this loop has three returns. Has anyone out there seen or done this type of configuration, and if so what would the technique be called? Also why would you do this? There is plenty of places to T in for a seperate supply for each loop.The loop length I estimate at about 545'for the three rooms which would be way to long for 3/8" pipe.What ever technique it is called it works fine just wondering if anyone has seen or done this.