Pressure between the pump and CSV

[Mike56]

I've read a number of posts on the line pressure created by the CSV, no need to go into any details. My question is: With a 3/4hp pump the max pressure created in the line by the CSV will be X. Given an identical install, and the pump is now 1 hp, will the max pressure created by the CSV remain the same or will it increase? The 1 hp pump is this one: Franklin 1hp 10gpm 230v 3W 4" SS 4400 TRI Series FPS, static water is at 40', pump at 60'.

[Cary Austin]

The back pressure to a Cycle Stop Valve is always whatever the pump can supply.  Looking at the curve for the 10 GPM, 1HP pump you mention it has a shut off head of 450'.  Subtracting the 40' for the static level leaves 410' or 177 PSI back pressure.  That is not too much for the CSV1A but is for the CSV125. 

That pump is really designed for a well with water at 200' or more.  The back pressure from the CSV is needed to keep that pump from upthrusting, as it is in a much shallower well than it was designed for.

A 15 or 20 GPM, 1HP would be better suited for a 40'-60' well and would only have 80-120 PSI back pressure.

[Mike56]

Thanks, Cary. The well guys put this in because that's all they had on their truck, saying it would be no issue. I suspected it wasn't right. They replaced a 3/4hp, 10gpm. I need to have this corrected to a 3/4 or even 1/2hp with this well setup, correct?

[Cary Austin]

With the CSV1A adding additional back pressure it can make the pump think the well is deeper.  So, you should be fine as is.  But if you get a chance to change it the 1HP motor is fine, even with a 3/4HP pump end.  You could put a 10 GPM, 3/4HP pump on the 1HP motor, or replace the 10 GPM, 1HP pump end with a 15-18 GPM, 1HP pump end.