I'm desiging a hot water regulator.  I'm pushing hot water through 4 loops which are around 150 feet long.  The tubing I was going to use has a 3/8" I.D. with about 2.5 gpm flow... the pressure drops are huge. 

I used the pressure drop calc. found at the link below to calculate the pressure drop just through the pipe (no minor head loss) and got 160 psi!  Does this sound right?  this is 370 ft of head, I'd need a huge pump for that. 

carf-engineering.com

Do I have my wires crossed?  Is this pressure drop not related to Head? Or is my pipe just two small, 2.5 gpm isn't alot of water?