I have the same problem, i am 24, no thats what the system is piped in but about ten years ago ,my mum and dad got a guy in to put a new rad on a nother wall with flow and return on opposite ends, he done this by teeing into the main flow and return and feeding 10mm to the new rad, i have just replaced that rad and re-piped it from his tee's on the main f and r . when all was done and i fired the boiler up the flow was going into the left side of the rad
as long as it's working leave it alone
see you young ung need us old hands regardless of your lip
Us young ones are the future, but we do get a bit stuck when it comes to systems that are older than our grandfathers