Condensing gas boilers similarly run more efficiently at lower temps.

If the water returning to the boiler isn't below 54C then there will be no condensing at all, and the advertised 90%+ efficiency won't happen till the return value is more like 46C.

That translates roughly to max winter temp of 65C leaving the boiler and lower when lesss heating is required.

This can be tweaked by the end user and save 10-20% on heating bills.