I have a heat pump AC unit in Florida that pulls well water into the AC unit/heat pump. The old 1/2 hp jet pump was about5 years old and died so I replaced it. It was a Sta-Rite blue cast iron FSNCHL type model with the big "head" behind the jet. I think that "head" helps on start up to create a LOT of pressure to get the water moving. It look like an "old school" style pump. Looks like this:
http://www.doityourself.com/invt/6396147

The guy at the pump place suggested the lower profile because the ground water is pretty salty. These moder style pumps with thermoplastic handle salt better. The model is a Sta Rite PNCIL. It looks like this.

http://www.hardwareandtools.com/invt/6968051

Well I took his advice and went with the low profile instead of stick with my old school style pump. I checked all my pvc fittings to insure no air leaks. Has a hose hooked up to prime. I ran the hose for about 10 minutes - shut the hose valve up and it could not pull from the well. I tried running it on the hose and slowly closing off the hose valve to see if it would start pulling from the well. No luck. Everything will work off the hose but my water bill will be a fortune and the hose water is not as cool at well water.

I am going to call in a well guy but I think the older style cast iron blue big head pumps have a stronger pull at start up. I think the low profile pumps may be almost worthless. I have tapped on the brass check valve at the ground level going down to the well to make sure that is not stuck. The check valve is at ground level and the pump is less than a foot off the ground on blocks. Should I try to swap out the low profile pump for the old style blue cast iron with the big head? i fooled around all weekend with this. Thank goodness I have a back up a/c. Thank you.