Condensing Temps for Oil Boiler

[Fly100]

Hello all,

Could someone give me a definitive answer on when an Oil Boiler stops condensing. I’ve read a good few pages and there seems to be conflicting info. Two options are its stops at 47C return temp or 55C return temp.Am I right in thinking the lower you can get the return the more condensing you get increasing efficiency ?

Thanks,

Fly

[JohnMo]

Here is a simple graph.  Oil has a lower condensing temp compared to gas