2 speed pumps and variable

[bullet20]

Been seeing some reports about this,what is the purpose for this pumps and a purpose pump?

 

[JasonLion]

Using a two speed or variable speed pump can save you a substantial amount of money on electricity. In general the lower the pump speed, the more efficient the system and the less you end up paying for electricity. Variable speed pumps are not usually worth the extra money unless your electric rates are above $0.20/kwh, while a two speed is worth it even at very low electric rates. Also, it isn't normally worth replacing a working pump, unless your electric rates are very very high.