They make the Sub drive look very inviting, and it is if it would last. I talked to a pump man in NC the other day who is not having much problem with the Sub Drive, and has some that are over 4 years old. However, his installations are on homes with no irrigation and no heat pump. So when just using water for home use they seem to be lasting a while. I heard from another installer in NM and another in Montana that can’t keep them running six months, because they have irrigation and evaporative coolers making them work more.
Of course you can use the Sub Drive with a regular pressure switch and CSV. There are a lot of people fixing them this way. Then you can use all the draw down from the tank, and the CSV keeps the Sub Drive switch from having to make and break 45 times per minute, which seems to be the essence of their problem. See attached.
