No pulsing water pumps
An interesting question came up on the Yahoo board concerning water pumps. It was in combine with several others that had pump issues.
The poster had replaced his Shurflo stock pump, with a Shurflo model that promised less cycling, pulsing, and noise. His issue was getting the pump to prime, which is probably not related to the other issues or probably not the pump, but when I looked up the pump, it was a very unusual setup from what I am used to seeing in pumps.
I am used to seeing mostly 3 kinds of pumps. Pressure controlled shut off/on like the basic Shurflo is, variable speed to control flow to match use controlled by pressure like the Flojet new model is, and bypass pumps that run full speed at pressure with any excess flow going through a bypass back to the inlet of the pump.
The Shurflo in question is a pressure shutoff and bypass pump, with both active at the same time, which I have not seen before. It appears they are balancing the bypass flow to reduce pulsing, against the shutoff pressure from the pressure switch. There were notes all over the manual for the pump about how critical the settings are, so I do wonder how they will do as parts in them age. A full pressure (almost full pressure in this case) pump also uses full power whenever running, as it is pumping full pressure and volume when running, so it would probably be using more power than an on/off or especially a variable speed.
It will be interesting to see how they work and hold up once there are more of them in the field.