Hmmmm. Good question.
Typicaly one wants to maintain some minimum overpressurization of building to minimize infiltration. In some cases, folks only consider keeping too cold, or too warm air from "leaking" into building. But in truth one is also concerned with infiltrating humidity and...
Hmmm. Several things about this discussion bother me.
The quoted hot water temperatures are high. Yep, one can achieve these easily enough in a pressurized system. I've worked with such in the past. But where is THIS system installed, and why are they using a pressurized system? Pressurized...