Another Water Pump Question

[MeetJohnDoe]

What is the difference between an "automatic constant pressure" water pump and "automatic" water pumps?

Most of the major water pump brands in Thailand offer these two types for typical household installations but it's difficult to get any information from store sales staffs (in English). The "constant pressure" models seem to be smaller, have small water-bladders, and have inverter models that are more energy efficient. The "automatic" pumps are much bigger (have large bladders).

Are there any functional differences between them and is one type to be preferred over the other in a typical Thailand household set-up? (I have city water, SS water tank, and pump between tank and house water intake.)