Hydraulic changes due to pipe upgrade

[mas985]

The change in head loss for pipe is proportional to the fifth power of diameter. For fittings it is the forth power. So going from a 1.5" pipe to a 2" pipe is a 1.284 ratio in I.D. so pipe head loss would change by a ratio of 3.48:1 and fittings by a ratio of 2.72:1. Not all of the pressure that is measured by a filter gauge is reflective of the pipe and/or fittings. The filter also contributes to the pressure and that would not change. Plus the interaction with the pump head curve complicates things. But yes, it is possible that the return head loss is halved by what you did. That is why I always tell people to forget about using swept 90s. The pipe diameter is a much more impactful change.

But also keep in mind that reducing the return side head loss increases pump flow rate and while you might think that is a good thing, the pump will actually draw more power because of that. So your energy costs will go up unless you reduce pump run time.

[EDIT] - I neglected the in-floor system. Those tend to generate a lot of pressure so when you took these two pressure measurements, was the in-floor engaged or bypassed in some way? 10 PSI seems low when using an in-floor system.