Question concerning condensing boilers/heating systems. I was always told to get a boiler to condense, we needed a return of minumum of 40 deg, better being 50 deg, delta T. So, if i need a supply temp of 180 deg, I wont truly be condensing unless i have a return of 130 deg, while needing to maintain my supply of 180 out. My boiler would need to be able to heat the "media" 50 deg. If that makes sense or not, tell me i'm wrong.
Yesterday though, i had a (controls) programmer tell me i'm wrong. It has nothing to do with delta t, and is only condensing if the boiler is run at a lower temp, 120 deg or so. ( and cant condense at 180 deg supply) Essentially he said, running a system at 120 deg with a delta T of 20 deg, would be more condensing than running at 180 deg with a 40 deg delta T. Granted the system has to be designed for either way.