Need help with 2 CSVs

[NathanJ]

My water system/conditions:
3/4 HP pump(goulds 7GS07422) placed at 240'
Water level 10' from surface
32 gallon pressure tank.


I attempted to install a CSV1Z before my pressure tank with a pressure gauge Tee'd in before the valve.  The pressure I was seeing on my gauge was 160PSI pretty steadily once the valve was holding back the flow.  I have 160 PSI poly pipe running in the ground to the house so I realized that I wouldn't be able to safely use that valve at that location.  I was also near the limit of the valve's 125PSI differential pressure if set to 50PSI output, with a 110psi difference.

Luckly, I have PVC down my well so it can withstand the higher line pressures from the CSV.  I purchased a CSV1W to put below the pitless adapater to hold the water pressure to something high like 90 or 100 psi and then use the CSV1Z in the basement acheive the final pressure.  That would have given me differential pressures of 70 and 40, both easily withing the limits of the valves and my 160PSI pipe would have been safe. Now that I have the CSV1W in my hand I noticed that the pressure max is 70PSI.  With the height difference of the well from my house, I wouldn't be surprised to see 170PSI at the pitless.  If I just use the well CSV at set it to 50, the differential pressure is 120+.  I also wouldn't be able to put a pressure gauge on it to verify acceptable pressures to not damage the valve.

What is the recommmend install for me?  Do I crank the CSV1Z up as high as it goes and then install it, and then fine tune the pressure with my other CSV?  I don't understand the proper way to set pressures with multiple CSVs.

I appreciate any help,
Nathan Jones

[Cary Austin]

You don't need two CSV's.  The back pressure is determined by the pump and static water level.  Having two valves won't change that.  The 125 PSI differential is the max recommended but, the CSV1Z will easily handle more than that.  The 160 PSI rating on your poly pipe is a working pressure.  The actual burst pressure is 2 to 5 times more than that.

You can use two CSV's in series to stair step the pressure down, so you don't have more than 125 PSI difference on either valve.  It will not change the back pressure, which again is determined by how much pressure your pump can build, less the depth to static level.

In your case you don't have more than 125 differential.  So just use the CSV1Z, set it at 50 PSI, and don't worry about the back pressure or differential.

[NathanJ]

I wasn't sure if running the CSV so close to the max diff pressure would damage the diaphram.  I shouldn't ever see more pressure than I have right now because if my water level rises any more it will be flowing out the top.

I will only run 1 CSV but I may choose the CSV1W because I would rather run the PE pipe well within the specified limits.  Is the CSV1W as capable as the CSV1Z model for my application?

Am I being overly conservative in not wanting to run the 160 PSI pipe at the 160-170 pressure?  I would hate to have a broken pipe in the ground and have to dig a new trench.

[Cary Austin]

The CSV1W works great at 50 PSI.  The CSV1Z works better if you need to increase the pressure to 60 or 70.  The 160 poly pipe will be fine.  The barb fittiings with hose clamps are the weakest link.  The barb fittings won't pop off burried pipe.  Hose clamps above ground need to be tight, and use two clamps if possible.

[steve10kinley]

Is there a procedure I can perform on an existing pump that will tell me if it will exceed the relief valve pressure or worse the 160 PSI rating on my poly pipe when throttled back to 1 gal/min?

The well has a 2.5 hp pump at 75 feet and a static water level of 20 feet.

However I do not have a pump pressure curve for this specific pump.

[Cary Austin]

A 2.5 HP pump would be very unusual.  If you can give me a model number for the pump, I can tell you the amount of back pressure.  Otherwise , you will need to just put on a pressure gauge and close a ball valve to see how much pressure the pump will build.