Pump ?

I have an old dug well with a 1" poly suction pipe in the basement. The well is about 60' away from the house. I'd like to setup a sprinkler pump, but the 1 1/2 hp pump I have has a 1 1/2 inlet and it's only building about 20 psi of pressure with outlets closed. I'm assuming the 1" suction pipe is the problem. Could something else be causing this? Thanks.

The suction pipe should never be smaller than the inlet of the pump, and if it is a long line, it should be one size larger than the pump inlet.

Find out what kind of pump you have. What make/model. A 1 1/2 HP pump with 1 1/2 inlet could be a centrifugal that would probably pump 50 to 70 GPM at low head, or 30 GPM at higher head, or a big shallow well jet, or even a multistage centrifugal. What you describe would fit one of the pumps sold as "irrigators" that might pump 30 to 50 GPM.

If the pump head is quite short relative to its diameter, it is probably a centrifugal. If it is quite long relative to the diameter, it is probably a jet pump. Find the model number on the pump and you can probably find the characteristics with an internet search.

You have several posts running, but I just thought of a solution I hadn't thought of before. Since you have a dug well and you only have 1" suction line. Why not put a submersible pump in the well and push the water through the 1" poly. You can cram 20 gpm through 1" pipe without too much friction loss and you can do it with a 1hp or smaller, depending on how much water you need. But you can't do that with a jet or centrifugal through that small of a pipe.

bob...