closed loop system

[sjwalton]

ok i thought i knew what a closed loop system was but obviously i dont. I have searched and still dont have a decent definition. So....help....thanks

[Pikelet]

Closed loop systems simply take water from a standpipe or built in overflow, run it into a pump inlet and the pump squirts it back out into the tank, usually on the other side. There are no intervening sumps or tanks in the flow path that might evaporate or lose water - hence "closed" loop. Closed loop systems can involve some quite complicated plumbing but the principle is still the same.

 

That's the way I see it anyway.