This pump with CSV

[Tim Van]

See the attached table, which I had handy. Note the shutoff PSI, which represents the deadhead pressure at a given depth to water.

There are charts available for other pump sizes. In 10 GPM pumps, I think 1 HP would be plenty. Even 3/4 HP might be a good fit. If you add the CSV, allow maybe 10 ft or 5 PSI to compensate for a bit of resistance .

For irrigation, it is best if the load consumes most of the available GPM. For mixed use, that is not as easy to balance. I think there is a need for a valve to shut off irrigation loads if the water pressure drops below some setpoint, such as 45 PSI. Then it should turn back on when the pressure rises. That way household use would have priority. I don't know if such a valve exists at consumer prices. The CSV is nice for irrigation because it makes up for the varying load.

http://www.pressure-drop.com/Online-Calculator/ lets you predict a pressure drop. I would use 1 mm for the pipe roughness unless you have more info. You can select the units with the drop-downs. Take defaults, and don't forget to select US units at the bottom. I got 11.3 PSI drop for 20 GPM and 50 ft. I used 50 ft instead of 20 ft to compensate for fittings or whatever, and to make a more conservative estimate.

Good stuff! Thanks Reach4!

 

[Valveman]

I was just assuming you had 1" or 1 1/4" in the well. I had already figured you would have 30 PSI loss per 100' of 3/4 poly. I just didn't know the distance, which at 20 feet with some elbows is still going to be a 10-15 PSI loss, which makes the pump think it is 35' deeper than it really is.

A 2HP, 10 gpm would have 311 PSI backpressure and won't deliver anymore than the 1HP , 10gpm pump, so you do not want a 10 GPM, 2HP.

You can add a little large pump to make up for the pressure loss in the 3/4 poly, but at 20 GPM the velocity is 12 feet per second. That is not good for the pipe either. Just like a garden hose isn't large enough to suck a golf ball through it, 3/4 poly is not big enough for 20+ GPM.

 

[Sponsor]

 

[Tim Van]

I was just assuming you had 1" or 1 1/4" in the well. I had already figured you would have 30 PSI loss per 100' of 3/4 poly. I just didn't know the distance, which at 20 feet with some elbows is still going to be a 10-15 PSI loss, which makes the pump think it is 35' deeper than it really is.

A 2HP, 10 gpm would have 311 PSI backpressure and won't deliver anymore than the 1HP , 10gpm pump, so you do not want a 10 GPM, 2HP.

You can add a little large pump to make up for the pressure loss in the 3/4 poly, but at 20 GPM the velocity is 12 feet per second. That is not good for the pipe either. Just like a garden hose isn't large enough to suck a golf ball through it, 3/4 poly is not big enough for 20+ GPM.

Thanks again valveman! It's looking like the 1HP 10GPM will be the way to go.

 

[Tim Van]

Thanks again to both of you for helping me through all of this. I like learning new things and I have learned a whole lot since I presented my original question here!

 

[Valveman]

A 1HP, 10 GPM pump will produce about 160 PSI of backpressure when the water level is at 35'. But it will still pump 10 GPM at 50 PSI even when the water level is pulled down to 200'.

I would use a long barb fitting with a couple of hose clamps and put the CSV1A as the first thing on that pipe coming through the wall. Everything after the CSV will only see the 40/60 pressure.

 

[Tim Van]

A 1HP, 10 GPM pump will produce about 160 PSI of backpressure when the water level is at 35'. But it will still pump 10 GPM at 50 PSI even when the water level is pulled down to 200'.

I would use a long barb fitting with a couple of hose clamps and put the CSV1A as the first thing on that pipe coming through the wall. Everything after the CSV will only see the 40/60 pressure.

I'm currently using the CSV valve, being located inside the house, to my advantage when away on vacation and watering systems are automated - set to go off at certain times of the day for various places that need the water.

In the past, I've had a timer or some other part of the system fail so the water never turns off. I've added a NC contactor inline with the lines from the main power to the pressure switch. I use a microcontroller system I've created to sense the pressure on the line into the CSV. I know that if the pressure drops below 68# that there is a definite problem such as the water in the well dropping to low due to a leak somewhere. When that happens, the microcontroller opens the contacts of the contactor, shutting off the pump. It then checks periodically, turning the pump back on and then off again if the problem happens again. That way, things continue to water yet the well never gets to a level where the pump never "dead-heads(not sure if the correct term").

I'll obviously need to modify it all slightly for the different pressures of the 1HP 10GPM but would rather do it indoors, so I wonder if there is another way, like maybe a 130# (or so) pressure relief valve inside the well pipe at the top to blow it back into the well, while still maintaining a respectable pressure/flow into the current CSV.

I plan to add leak or flow sensors at various locations that water to detect over-watering and then "tweet" that information to me so I can shut down, or at least regulate those systems, but don't have that in place yet.

 

[Valveman]

That 68# number will probably still be good. I can see where that would be a good way to catch a big leak in the mainline. If you just need to protect from pumping the well dry a Cycle Sensor would be good. It looks as low amps that happen when the well pumps dry and shuts the pump off. Then it has a timer to restart the pump after the well has had 30-60 minutes to recover.

You can also use a low pressure cut off pressure switch. But those have to be manually reset if it goes off on low pressure, which is probably a good thing. The combination of a Cycle Sensor and a low pressure cut off switch will protect the pump from a mainline break and pumping the well dry.

 

[Tim Van]

That 68# number will probably still be good. I can see where that would be a good way to catch a big leak in the mainline. If you just need to protect from pumping the well dry a Cycle Sensor would be good. It looks as low amps that happen when the well pumps dry and shuts the pump off. Then it has a timer to restart the pump after the well has had 30-60 minutes to recover.

You can also use a low pressure cut off pressure switch. But those have to be manually reset if it goes off on low pressure, which is probably a good thing. The combination of a Cycle Sensor and a low pressure cut off switch will protect the pump from a mainline break and pumping the well dry.

Thanks valveman!
I can make up any of those systems myself, and have thought about it. The 1HP 20GPM never pumps down anywhere near where it's sitting, while maintaining any respectable pressure, so it may be harder to implement with that one since the current wouldn't change that much - I think. The 1HP 10GPM would pump right down to itself, at least at the 165' before I deepen the well (if I deepen it) so it would obviously work for it. However I'd think it would be best to never run it dry, even briefly, and running dry could happen frequently under certain scenarios.... I think.

My well is slow to recover at this time, and will remain so unless I have it deepened and fracked. So I want to pump as much as I can (1.3gal/foot?) which the 1HP GPM pump would obviously do during whatever maximum period of time possible. I wonder what the pressure on the CSV side of things might become as the water nears the pump so I can still use my system based on pressure on the pump side of the CSV as an "early warning" system?

 

[Valveman]

While pumping 10 GPM at 50 PSI, when the water level pulls down to 165', there will be 50 PSI coming out of the CSV and about 65 PSI on the inlet side of the CSV.

 

[Tim Van]

While pumping 10 GPM at 50 PSI, when the water level pulls down to 165', there will be 50 PSI coming out of the CSV and about 65 PSI on the inlet side of the CSV.

Thanks valveman! That should make it easy for my system to monitor. Still not sure what to do about the extra pressure if I keep the CSV inside. Perhaps a 125psi pressure relief valve with a 10' piece of pipe to blow it back down into the well. Or maybe when it comes time, I may decide to just put the CSV near the well, or even just go-for-it and remove a piece of a walkway, do some digging/tunneling, and replace all that 3/4" poly. I'll have to look back in all of this and see if you've said that the 1-1/4" 60-year old poly down to the pump can take the 165# pressure the pump will put out at times. Which brings me to the question: will the pump always put out 165# "down near the pump" regardless of the water level, or does that change with the water level?

 

[Valveman]

Thanks valveman! That should make it easy for my system to monitor. Still not sure what to do about the extra pressure if I keep the CSV inside. Perhaps a 125psi pressure relief valve with a 10' piece of pipe to blow it back down into the well. Or maybe when it comes time, I may decide to just put the CSV near the well, or even just go-for-it and remove a piece of a walkway, do some digging/tunneling, and replace all that 3/4" poly. I'll have to look back in all of this and see if you've said that the 1-1/4" 60-year old poly down to the pump can take the 165# pressure the pump will put out at times. Which brings me to the question: will the pump always put out 165# "down near the pump" regardless of the water level, or does that change with the water level?

No you do not want to use a pressure relief and dump excess pressure. That really stirs up a well, doesn't let the CSV do it's job, and would quickly wear out a pressure relief valve as they are only made to work in an emergency.

Yes the pump will always have 165 PSI when working with the CSV, as that is how much pressure the pump can build when pumping 1 GPM. But the 165 PSI from a CSV is much less than the water hammer pressure that happens when a pump is just cycling on and off.

Actually 3/4" pipe will have a higher pressure rating than 1" or 1 1/4". It is the higher volume you can't get through the smaller pipe.

 

[Tim Van]

No you do not want to use a pressure relief and dump excess pressure. That really stirs up a well, doesn't let the CSV do it's job, and would quickly wear out a pressure relief valve as they are only made to work in an emergency.

Yes the pump will always have 165 PSI when working with the CSV, as that is how much pressure the pump can build when pumping 1 GPM. But the 165 PSI from a CSV is much less than the water hammer pressure that happens when a pump is just cycling on and off.

Actually 3/4" pipe will have a higher pressure rating than 1" or 1 1/4". It is the higher volume you can't get through the smaller pipe.

Once again, thanks valveman for sticking with me on this, as it's a lot to take in.

So I wonder what the "water hammer pressure" would have been (before I put in the CSV) in my system with the current 1HP 20GPM pump set at 165'. Knowing that, and knowing that all the existing piping (in the well and into the house) has survived it, might help me determine if the new 1HP 10GPM using the CSV would survive as well, which may not otherwise survive without the CSV and "water-hammer" pressure.

Then the only thing to be considered is if I should replace the pipe from the well to the house (a difficult task due to a sidewalk and raised planter space between well and house) to take advantage of the available volume.

 

[Reach4]

Which brings me to the question: will the pump always put out 165# "down near the pump" regardless of the water level, or does that change with the water level?

It would be very unusual to have that same 3/4 inch poly pipe going down to the pump. Usually the 3/4 poly would only go to the pitless and the pump would be hanging on something else, such as 1 inch schedule 80 PVC. So if you had 165PSI at the output of the pump, you would have 165 at the water surface. Then if the water level is 30 ft below ground, and the pitless is 4 ft below ground, the 3/4 poly would see 165-11=154 PSI.

 

[Tim Van]

It would be very unusual to have that same 3/4 inch poly pipe going down to the pump. Usually the 3/4 poly would only go to the pitless and the pump would be hanging on something else, such as 1 inch schedule 80 PVC. So if you had 165PSI at the output of the pump, you would have 165 at the water surface. Then if the water level is 30 ft below ground, and the pitless is 4 ft below ground, the 3/4 poly would see 165-11=154 PSI.

Thanks Reach4. It's 1-1/4" in the well down to the pump. Was trying to determine if that 60 year old poly would take the pressure.

 

[Reach4]

Thanks Reach4. It's 1-1/4" in the well down to the pump. Was trying to determine if that 60 year old poly would take the pressure.

Poly pipe used for well lines is usually ASTM D2239 (SIDR) In this spec, the ID is the same for a given nominal size. So ID for "3/4" is 0.824 inches, and the outside varies. The OD varies according to the wall thickness. So the OD could be used to predict the pressure rating. This OD would not be measured over a barb.

I don't know how effective this would be, but it would be a guide to an estimate.

 

[Tim Van]

Poly pipe used for well lines is usually ASTM D2239 (SIDR) In this spec, the ID is the same for a given nominal size. So ID for "3/4" is 0.824 inches, and the outside varies. The OD varies according to the wall thickness. So the OD could be used to predict the pressure rating. This OD would not be measured over a barb.

I don't know how effective this would be, but it would be a guide to an estimate.

From what I've been able to find, the black poly 1-1/4" going down to my pump is only rated at 125psi. I'm guessing it's bursting psi may be double, or even triple that. So I wonder how safe it would be to put the new 1HP 10GPM pump that puts out up to 165psi on the end of that pipe. Is it common practice to go a "little" above the rated psi?

 

[Valveman]

I have not heard of 125# rated poly. Only 160# and 200#. Some of the really older stuff can be 100#, but that is rare. The burst pressure is usually 3 to 5 times the rated pressure. Rated pressure is usually very conservative. Water hammer spikes from starting and stopping a pump can be 5 to 10 times the running pressure. The weak point of poly is the barb fitting. If the barb fitting is good the pipe can handle tremendous presure.

 

[Tim Van]

I have not heard of 125# rated poly. Only 160# and 200#. Some of the really older stuff can be 100#, but that is rare. The burst pressure is usually 3 to 5 times the rated pressure. Rated pressure is usually very conservative. Water hammer spikes from starting and stopping a pump can be 5 to 10 times the running pressure. The weak point of poly is the barb fitting. If the barb fitting is good the pipe can handle tremendous presure.

Perfect - thanks.

Looks like I'm good to go then. Will keep my 1HP 20GPM in place for a while longer since other than not pumping the water down anywhere near where it's sitting at 165' (while maintaining decent pressure), it's still functioning okay. When I have a chance, I'll replace it with the 1HP 10GPM so I can get more water out of the well making it possible to water more before having to wait for the well's slow recovery. As mentioned, somewhere in all of this, the recovery isn't a "huge" problem since I can irrigate in the morning before going to work, and in the evening before going to bed. If the recovery becomes even worse, I'll have the well deepened, fracked, go ahead and do the work of replacing the 3/4" pipe from the well to the house with 1", or maybe even 1-1/4", and install a 1-1/2HP 10GPM or 15GPM, at 280' on new heavier pipe.

I've learned a lot here. Going to print all of this out and study it until I understand it all even better.