Sizing well pump drop pipe
That is a large increase in hp, what gpm is the 1 hp rated at; pumps come in two parts; hp and gpm.
What is your peak demand gpm flow rate?
You size a pump based on the gpm you need and the psi you are running the system at and then find the number of horses needed, not by hp alone. There are negatives in over sizing a pump.
Usually, for a 120' depth and an average peak demand flow rate of like 12 gpm, a 1/2 hp 10-13 gpm pump would be more than enough pump.
The 1" is just fine, and you probably have 1" at the pressure tank, or a 1" tank Tee right, so going larger than 1" is not needed 'cuz ya can't use the additional flow anyway.
Why are you replacing the pump?
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