Q about cycle stop valve pump pressure

[Guy48065]

I've been on the fence for awhile about installing a CSV in the well systems at my home & also my cottage. I like the concept but just now I happened on a forum post about high pump pressure. In that post 150psi pump pressure was called "just right" but seems really excessive to me and I'd like to know why this is a good thing.
My home system has a submersible pump with black poly pipe underground, thru the basement wall, right up to the pressure tank tee. Concern here is the poly pipe.
My cottage system has a 1/2HP Gould J5SH shallow-well pump in the basement that I doubt could muster anything near 150psi. I don't know what's underground out to the well casing but it's galv. thru the basement wall & into the pump.

 

[Reach4]

The time when the 150 would be just right before the CSV would be with some submersible pumps. It's not that the 150 is desirable in itself, but that is what it takes to throttle some pumps to a lower flow. There are pumps, usually for much deeper wells, that would take too much pressure to throttle them. Those applications would not be right for a CSV. Pretty much all potable water piping can take 150.

 

[Sponsor]

 

[Guy48065]

The time when the 150 would be just right before the CSV would be with some submersible pumps. It's not that the 150 is desirable in itself, but that is what it takes to throttle some pumps to a lower flow. There are pumps, usually for much deeper wells, that would take too much pressure to throttle them. Those applications would not be right for a CSV. Pretty much all potable water piping can take 150.

The linked older thread said poly pipe is only rated for 80-100psi.
It could be a very expensive mistake to burst a pipe under a driveway.
OR for the indoor portion to burst, for that matter.

 

[Reach4]

The linked older thread said poly pipe is only rated for 80-100psi.

I think you contorted that a bit. This was the actual statement.

The old thin poly was rated for 80 psi & 100 psi and won't hold up.

Clearly that referenced old thin pipe would not be would not be appropriate for a submersible pump and a CSV. Thus a CSV would not be a good idea for your home unless you determined if your pipe was appropriate with your pump and the CSV. 160 psi and higher pipe is common today. Note that 160 would be a working pressure. The burst pressure would be much higher.

If your point was that 150 psi into a CSV is usually not a design target, I agree. It can be within the upper end of the good range.

The highest pressure would occur in the well, and the pressure from the pump gets less and less as the pipe wire rises from the water. Some pumps are hung from poly pipe, most popular today is PVC, and steel pipe is still used a fair amount. I guess in your case, you are thinking of the topside poly pipes.

 

[Valveman]

Higher back pressure is good for a pump. It makes the motor draw lower amps and run cooler. The back pressure is also how the CSV throttles the pump to keep it from cycling on/off repeatedly, which is how the CSV saves the pump. The back pressure is always different for different pumps, and your jet pump builds a max pressure of 74 PSI, so this is a moot point. Like other things about pumps, higher back pressure being good is counter intuitive. The back pressure does need to be figured and considered, but is rarely a problem. The back pressure from a CSV will actually make pumps last several times longer than without a CSV. Installers are either uneducated or just being "shifty" if they use the counter intuitive issue of back pressure to talk people out of a CSV. I am afraid many of them perpetuate this "rumor" because they don't want everyone to have a CSV and have their pump last 53 years like this one.
https://terrylove.com/forums/index....anyone-know-what-kind-of-valve-this-is.83778/



Thanks

 

[Guy48065]

I don't think I'll risk it on the system with poly pipe. The tubing is original to the house, built mid-70's.

This back pressure--it exists both while running and as a spike when it shuts off?
What effect does this have to starting current?

 

[Reach4]

What effect does this have to starting current?

Very little. The CSV would be open when the pump starts.

 

[Valveman]

The CSV can be set to be in the almost closed position when the pump starts. Starting the pump against pressure (closed valve) actually makes it easier for the pump to start. The CSV greatly shortens the duration of the inrush start current.

Your poly pipe is experiencing much more pressure without a CSV than it would with a CSV. The CSV also reduces the flow rate to 1 GPM before the pump shuts off. This eliminates the water hammer pressure spike that happens when a check valve slams shut from full flow like it does when not using a CSV. The 74 PSI back pressure is the most you would see with a CSV. But without a CSV the water hammer that happens when the pump shuts off can be 5 to 10 times that much. There are no negatives to using a CSV. Back pressure is a good thing. But many people use that to scare you away from using something that would make everything in your pump system last many times longer than normal. Plus, everybody likes the constant pressure from a CSV compared to the old 30/50 or 40/60 pressure swings of the old style systems.

Oh and another BTW, the back pressure is only on the pipe between the CSV and the pump, not on the suction line or after the CSV. Most jet pump systems only have a short nipple between the CSV and pump, which would be the only piece to see the 74 PSI back pressure. However, when using a foot valve, the suction line will see the water hammer spike pressure when the foot valve closes, which doesn't happen when using a CSV.

 

[Guy48065]

Valveman did you read the post I referenced in #1 because in it YOU said 150 psi is normal and "just right".
Now you claim half that, or less.
I'm trying to understand but I see red flags when the stated numbers change dramatically.

 

[Valveman]

150 PSI is just as normal as 74 PSI. The back pressure from a CSV depends on how much back pressure your pump can build. Your J5SH can only build 83 PSI max, so 83 PSI is all the back pressure you will see. If you had a deep set submersible pump and a high static water level you might see the 150 PSI, which would still be OK because that pump can easily build 150 PSI, yours cannot.

Then again, there is only back pressure on the pipe between the pump and CSV, which in your case is probably only a 3" or 6" long nipple. All the pipe before the pump is a suction line, and all the pipe after the CSV will only see 40 to 60 and the CSV will keep it at 50 PSI constant anytime you are using water.

And one more time again, BACK PRESSURE IS A GOOD THING. It is what the CSV does to eliminate the destructive cycling, lowers the amps and make the motor run cooler, and many other beneficial things. Good pump men have been adjusting valves to add back pressure to pumps when needed for a century. A good pump man would know increasing back pressure is good for the pump. It is what we have to do to many big centrifugal pumps to keep them from drawing too much current and tripping the overload.

And hey a CSV is not for everyone. If you just let an installer sell you what HE thinks you need and don't want to educate yourself on the subject, then you are most likely going to pay way too much and have a water system that fails often. Only people who are tired of having regular pump problems or tired of paying a contractor too much and too often will appreciate the CSV. Once you have been through any of the normal pump problems caused by too much cycling the CSV is a no brainer. Most people go through their entire life never knowing that cycling is what causes all those problems and cost them so much money. People who are making a killing on pumps and don't want you to know that spread rumors about back pressure and pump companies not warranting their products to talk you out of a CSV. They don't want you to have a CSV pump system that will never cost you another penny, as that would never let them make another penny either.

 

[Guy48065]

As I've stated I have 2 homes and the concern over pump pressure is the system with a submersible pump feeding the pressure tank thru 30 feet of underground black poly pipe installed in 1975.

I really have no concerns about my shallow well cottage system. If the power hadn't gone out & froze the original (also 70's) pump, it would still be chugging along. Longevity isn't a concern due to infrequent use.

 

[Valveman]

Just need to know what submersible pump you have and how deep it is to water? Then I can figure the back pressure for you. The most common submersible is a 1/2HP, 10 GPM pump, and it will only build a max back pressure of 90 PSI. Most pumps cannot build more pressure than even old pipe can take.

But we also make the CSV125 that can fit in the well casing. That way only the pipe in the well see the back pressure and the underground line after the CSV never sees more than the 40/60 pressure switch. Longevity is one symptom of having a CSV, but strong constant pressure in the shower to keep the wife happy is the most obvious benefit of the CSV.