Quote Originally Posted by alacheesu View Post
I could be wrong, but I don't think it matters if you're pumping 20 feet straight up or 20 feet horizontally as long as it's a closed loop.
Quote Originally Posted by DeathWalking View Post
You're not wrong.
Alacheesu is right, height difference does not matter in a closed loop. The pressure you loose on the way up you get back on the way down so to say.

But it would likely be a hell to get a loop started if the internal height difference where larger then the pump head. And you would possibly get cavitation problems on the highest part due to low absolute pressure.