Finally got around to testing this. Got the pressure gauge. Pretty cool. The overflow pipe from my water heater doesn't have the threading. Put the gauge on my outside spicket and got about 68 psi. It spiked to 120 when I first turned it on.
Have not measured the water temp coming out of the heater, but I usually shower with no cold whatsoever, can't be too hot. We have (or at least had) small children, so we've always run it set just under "hot". Guess I could use a meat thermometer....
I'll report bck.