I have a CSV installed in a system using a 1 1/2 horse 19gpm F&W submersible pump set at 185' depth with 1 1/4 well pipe. I have a check valve in line at 100'. This is according to manufacturer's recommendation. I have a pressure gauge at the pressure switch, and I also purchased another one with my system, and installed it on the input side, just prior to my CSV, to monitor back pressure.
When I adjusted the CSV at 2gpm, my pressure switch at the CSV maintained 55psi, with a back pressure reading of 87lbs on the input side, prior to the CSV. This seemed reasonable, based upon the depth of the well, and the distance from my pitless adapter and the pump vault. My three outdoor hydrants with a one inch supply line measured about 56psi static pressure. This worked as designed with the pump cycling once during water usage. The needle on the pressure valve would flicker when it hit the 87psi mark, but it stayed at 87psi. Presently, everything works fine in terms of water usage, but under demand, the CSV reads a constant 55psi, but the backpressure gauge now reads 30psi. Is this possible? Output pressure greater than input pressure? Do you think that I may just have a defective pressure gauge on the input side? Please advise, thank you...