I live in SW Louisiana and there is a well on our family farm that was drilled about 40 years ago, it has a 2 inch PVC casing, and I think it is about 240 ft deep. Our area has 3 aquifers below it with the shallowest wells being only 20-30 ft deep into the sands of the upper aquifer, which is generally considered inferior for drinking water with the preferred drinking water well depths being 150-250 feet into the second aquifer. This well uses a belt driven compressor to force air down a line into the well which then lifts water (which surges) into a thousand gallon fiberglass storage tank with a float switch to control the well compressor, which in turn feeds a pressurizing pump with a bladder tank.

My current issue is that everyone that knew the exact details of the well are dead, and now it is need of a new compressor.

Here are the facts that I have, the current compressor block is a 2 cylinder type compressor with a finned line between them (I don't think it is 2 stage since both cylinders look to be the same size), and is driven by a 1HP electric motor. The compressor has no markings on it, and I know it is about 15 years old, so may not be sized correctly for the well. The pressurizing pump (Grundfos CHIE-2-40) spec sheet shows it is rated at a bit under 20 GPM max flow and with it running at full speed the compressor is able to recover water to the storage tank at a slightly higher rate than the pressurizing pump empties it, I would guess this rate is around 25-30 gpm average out of the well.

What I need to know is what should I be shopping for in a new compressor block, I have no idea of the rating of this one, there are no markings on it at all. Also is 1HP the appropriate size motor, and how do you size a compressor for an air lift well?

thanks for your help