Pump cycling no pressure tank

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Speedbump

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With the CSV, even if the tank goes bad, the pump still won't cycle. That's one of the neat things about a CSV, it even saves the motor when a Big Box tank goes south.

bob...
 

Themp

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I increased the high pressure cut off and all is well on the cycling problem during hose spraying. Thanks for the many responses, really liked the continous run option using a feed back to the rain barrel, one less mechanical part.

Tom
 

riccet

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Hi, couldn't get registered in time, I see you have fixed the issue.:D

I have a similar setup for my green house, but I use drippers and sprayers off of a sump pump. The pump was a hand-me-down that was way too powerful for the drippers, so what I did was put a 'Y' in the output with one hose feeding the drippers and one hose with a valve back to the source. I just vary the valve opening to control the pressure to the drippers. I accidentally left this running for a weekend and it was fine. I've been using it for over four years without a hitch.
 

Speedbump

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The pump was a hand-me-down that was way too powerful for the drippers,

Sump pumps don't typically make more than 13 psi or so. I don't see how it could be too powerful. I can't imagine your drippers wanting less than 13 lbs. Shut off the return valve and the motor will just be idling as opposed to pulling max amps moving a lot of water.

bob...
 

Bill Arden

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Just trading 2 problems for 10. Here is what I think about VFD pumps.
http://cyclestopvalves.com/comparisons_14.html

I used to have a good opinion of cyclestopvalves.com, but that page makes me want to cringe.

VFD's are very reliable and efficient, they just are too expensive.

1. They do not fail every few years. I know the ones the local city sewer system uses for the lift pumps have been running for over 20 years.

2. They don't consume any power when the "pressure switch turns off" since you can use a regular pressure switch to disconnect power to the drive.

3. The power they use in a tank-less system is LESS than what the pump would use pushing against the CSV
http://cyclestopvalves.com/comparisons_13.html
quote - "At 100 GPM and 231' of head,"
You did not add the extra head pressure that the CSV adds when it's closed against the full RPM pump speed.
It should be at least 270' of head according to your chart.

Also most customers don't have 231' feet to the water table. The higher the static level, the worse your numbers get.

You also don't specify the VFD output voltage profile, if it's "sine wave output", or how much the rotor speed was allowed to drop below the driven frequency.

3. Define "fluid system"
I do not have any valid context to define what that means other than the system contains water.

4. I agree that the "throw away society" needs to ask for better, but that is a product specific issue and not a argument against VFD technology.

I agree that a CSV is a good choice due to the price, but Brush-less PDC motors are going to get better and better...
 

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"VFD's are very reliable and efficient, they just are too expensive." Bill Arden

VFD's are getting cheaper but, they are not reliable. It is the exception to see one that has lasted 20 years, not the norm. Any that I have seen that lasted 10 years, did so by virtue of several repairs. A few of the larger HP VFD's my have lasted that long but, they don't even make them like that anymore, those I am sure are not even using IGBT. Since there were a few of them that have lasted 20 years, they now use a single power pack instead of a power pack for each phase, and other such things to cheapen them up and keep them from lasting as long. See the following link, that is from a company who sells VFD's.

http://www.powerqualityanddrives.com/payback_analysis_vfd/

"They don't consume any power when the "pressure switch turns off" since you can use a regular pressure switch to disconnect power to the drive." Bill Arden

There is only one company that makes VFD's for pumps that uses a switch instead of a transducer. Even in this case the switch does not shut off power to the VFD. The VFD stays powered up, keeps 230 volts at 0 hertz to the motor all the time, and continues to use energy even when the pump is not running. Standby mode uses 40 watts with small VFD's, and considerably more watts for larger VFD's. The "parasitic" losses of the VFD means that the VFD itself consumes power while the motor is running. Read the "heat losses" for VFD controls in their own installation manual, and you will see that the smallest VFD uses 189 watts and larger ones can use up to 7400 watts, then you add the motor load.

"The power they use in a tank-less system is LESS than what the pump would use pushing against the CSV" Bill Arden

In a tankless system the pump must run for you to get a single glass of water. Utilizing a pressure tank with the CSV, the pump does not even come on until you have used all the water from the tank. Pump running with tankless system uses power. Water coming from pressure tank on CSV system, pump is not running or using power.

"At 100 GPM and 231' of head,"
"You did not add the extra head pressure that the CSV adds when it's closed against the full RPM pump speed. It should be at least 270' of head according to your chart." Bill Arden

The head loss across the valve depends on which valve you are using, but you are right, there is some loss across a valve. However, the head loss across a valve is usually not as much energy wasted as the "parasitic losses" of a VFD as described above.

"Also most customers don't have 231' feet to the water table. The higher the static level, the worse your numbers get." Bill Arden

A low producing well with a high static will allow for more variation in speed when using a VFD. However, it is a low producing well and the pump is not going to run long enough for a Drive to be of any benefit. Normal producing wells usually have very little difference in there static and pumping level. Any long term uses of water will be lifted from the "pumping level". Which means if the pumping level is 231', it will stay at 231' as long as you are using water, which further eliminates the usefulness of a VFD.

"You also don't specify the VFD output voltage profile, if it's "sine wave output", or how much the rotor speed was allowed to drop below the driven frequency." Bill Arden

Most VFD's are now using an equal volts to hertz ratio, and try to simulate (as best as they can) a true sinusoidal wave. The curve shows the RPM dropping from 3550 to 3280 RPM, which if you do the math, means 92% of speed or about 55 hertz. Which is about all the speed variation you can get with a VFD unless you way oversize the pump to start with.

"Define "fluid system. I do not have any valid context to define what that means other than the system contains water." Bill Arden

One of the biggest problems with VFD controls is that they were designed to be a "fluid system". For a manufacturer, a "fluid system" has nothing to do with water. A "fluid system" is a product designed to cost a lot up front, doesn't last very long, is not repairable, and because it controls your water supply, must be replaced as soon as it fails. "Fluid systems" are great for the manufacturer, because the homeowner must continue to shell out cash to keep his water flowing. "Fluid systems" are also known as "planned obsolescence".

"I agree that the "throw away society" needs to ask for better, but that is a product specific issue and not a argument against VFD technology." Bill Arden

The VFD is the specific product in question. There are many good applications for a VFD but, since they do not save any energy on most centrifugal pump systems, they are being used to control the life of the pump system, add additional cost for the end user, and make more profit for the manufacturer.

"I agree that a CSV is a good choice due to the price, but Brush-less PDC motors are going to get better and better..." Bill Arden

You were just talking about the "sine wave" so surely you know that they do not use DC motors with AC, pulse width modulating (PWM) VFD's. I guess we could go back 30 years and start using DC drives again. Even though VFD's are AC and use AC motors, the technology IS getting better and better. It has been getting better and better for 30 years, and is still not right. There are still some "laws of physics" as you claim to understand that cannot be changed. There are Resonance frequencies, harmonics, "ringing" which causes voltage spikes, "affinity law" which reduces the head by the square of the speed, and many other things that mother nature won't let a VFD correct.

I started with electronics and VFD's a couple of decades ago. I came to using Valves after realizing that there are many things about VFD control that can never be fixed. I really like my gadgets as with my computers, GPS, Blackberry, DVR, digital camera, etc., etc. I think there are some great applications for VFD's, and I even have a few on things like a treadmill. I don't expect these things to last very long and they usually don't. I have five old non working video cameras, several computers, and a pile of not very old VFD's that I need to throw away. Therefore I might use an electronic device to monitor but, never to control a critical system like my water supply. Else I would be out of water as often as I have to do a restart on my computer, or replace my video camera. Not acceptable!!!

What a VFD does is so complicated that most people with good electronic backgrounds do not fully understand them. There is no way the average person would ever have a clue. This makes it easy for the manufacturer to sell VFD's as a magic box that saves energy. If you "pay no attention to the man behind the curtain", you can easily fall for the VFD hype. Since the longest running VFD for small pumps has only been running 8 years, the average is much less than that. Most small VFD's are replaced as often as any other computer. This makes it impossible to save any money, when you are continually having to purchase new equipment just to keep your water flowing.

To someone who sells VFD's or does electronics for a living, my message is about as popular as a turd in a punch bowl. However, this does not make what I am saying any less the truth.

Sorry for the long post but, these were complicated questions that deserve a truthful response.
 

riccet

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Sump pumps don't typically make more than 13 psi or so. I don't see how it could be too powerful. I can't imagine your drippers wanting less than 13 lbs. Shut off the return valve and the motor will just be idling as opposed to pulling max amps moving a lot of water.

bob...

LOL The ends of the drippers and sprayers blast off and then I have to search the greenhouse for them.
 

Speedbump

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Really? I don't understand how that could happen, since most sump's just don't make pressure, they are a volume pump.

What pressures were these drippers and sprayers supposed to operate at. Most of the ones I'm familiar with like 40 plus PSI.

bob...
 

riccet

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Really? I don't understand how that could happen, since most sump's just don't make pressure, they are a volume pump.

What pressures were these drippers and sprayers supposed to operate at. Most of the ones I'm familiar with like 40 plus PSI.

bob...

So... You are the site troll?
 

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*ponders the thoughts*

VFD's are getting cheaper but, they are not reliable. It is the exception to see one that has lasted 20 years, not the norm. Any that I have seen that lasted 10 years, did so by virtue of several repairs.
This is an indication of engineers taking the "design life" too literally.
VFD technology is at the heart of the Prius hybrid car and most cars are expected to last 10 years or more.

See the following link, that is from a company who sells VFD's. http://www.powerqualityanddrives.com/payback_analysis_vfd/

It's clear that VFD's make the most sense at high power levels.
Hence the reason that the CSV is probably the best option for this thread's question.

At power levels greater than 10Hp it's normally cheaper to use 3 phase motors and VFD's

"They don't consume any power when the "pressure switch turns off" since you can use a regular pressure switch to disconnect power to the drive." Bill Arden
There is only one company that makes VFD's for pumps that uses a switch instead of a transducer.

There used to be technical problems with powering up and shutting off drives.
This is a implementation detail and can be improved.

"I agree that a CSV is a good choice due to the price, but Brush-less PDC motors are going to get better and better..." Bill Arden

You were just talking about the "sine wave" so surely you know that they do not use DC motors with AC, pulse width modulating (PWM) VFD's. I guess we could go back 30 years and start using DC drives again. Even though VFD's are AC and use AC motors, the technology IS getting better and better. It has been getting better and better for 30 years, and is still not right. There are still some "laws of physics" as you claim to understand that cannot be changed. There are Resonance frequencies, harmonics, "ringing" which causes voltage spikes, "affinity law" which reduces the head by the square of the speed, and many other things that mother nature won't let a VFD correct.

(context change) "Brush-less PDC motors" is a marketing term for a synchronous AC motor with a integrated controller.
http://en.wikipedia.org/wiki/Electric_motor#Brushless_DC_motors

High frequency ceramic core motors with rare earth magnets are the most efficient and powerful motors on the market.

Combine that with a screw compressor pump and you would have a awesome pump. ;) Unfortunately it would cost a fortune.
 
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Sorry Bill. I didn't understand that they where using "brushless DC" to describe what I thought was called a "permanent magnet" motor. I stand corrected.

However, I disagree that because a pump is larger than 10 HP a VFD would save energy. Attached is a curve of a 100 HP pump that shows only 4% difference at low flow and averages about 9% difference overall. The "parasitic" losses of the VFD will almost make it even. Then when needing to run the pump at full capacity, these "parasitic" along with efficiency losses from the harmonic current will make the VFD actually use more energy than with standard Across The Line controls.
Thanks
 

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Bill Arden

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However, I disagree that because a pump is larger than 10 HP a VFD would save energy.

I said it would be "cheaper" in post #33

Have you priced a 10Hp Single phase motor?

With the price of copper rising and the price of electronics falling I am going to guess that it gets to the 1hp well pump market in approximately 8 years (4*moore)

Then look at the power draw at startup and what effect that has on other equipment.

That is why I say it's generally cheaper to buy a 3 phase motor and a VFD at larger power levels.

efficiency losses from the harmonic current
True "sine wave" VFD's don't have "harmonic current" losses since they have inductors and capacitors after the H-Bridge to create a smooth Sine wave voltage.

The switching frequency is also increased to above 60Khz to reduce the size of the inductors.

For more info see what is called a "switching amplifier"
http://en.wikipedia.org/wiki/Switching_amplifier

Edit: clarification "Smooth sine wave" instead of "Constant DC"
 
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OK, I was trying to let this thread die because it will take me a long time to explain and most people don't understand what we are talking about anyway. That is the one of the main problems. Volts to hertz ratio, sign waves, harmonic currents, switching frequencies, inductors, H bridge, even the guys who sell this stuff don't know what all that means. The average home owner is supposed to just believe that a Variable Speed Pump is a "magic" box that saves energy and therefore is worth the added expense, short life expectancy, and all the trouble that goes with it. There are lots of good applications for variable speed equipment. With fresh water pumps however, VFD's are being used as a marketing tool to get more of your money, and to be able to get more of your money, more often.

"Have you priced a 10Hp Single phase motor?" Bill Arden

I use 10 HP single phase motors all the time. However, I would use three phase power when available for pumps as small as 3 HP. They also make phase converters, which I also use, to convert single phase to three phase without the problems of Frequency control.


"With the price of copper rising and the price of electronics falling I am going to guess that it gets to the 1hp well pump market in approximately 8 years (4*moore)" Bill Arden

Copper wire is something that will last, electronics is something that will not last. Which would you rather spend your money on? Grundfos already makes these small pumps and motors that work with "permanent magnets" and the Moore's law is how they finally got them this far. Just because a technology exist, doesn't mean that it is the best way to go.


"Then look at the power draw at startup and what effect that has on other equipment. That is why I say it's generally cheaper to buy a 3 phase motor and a VFD at larger power levels." Bill Arden

Single phase motors use a lot of power at startup. However, when used with a Cycle Stop Valve there are very few startups which usually makes starting currents unimportant. At larger power levels a 3 phase motor is preferable but, it doesn't need a VFD. With submersibles you can use the longest length of the smallest wire possible to create a natural soft start. This works with single phase and three phase. The smaller wire limits the inrush currents on startup, which naturally reduces the starting torque, without needing any complicated electronics.


"True "sine wave" VFD's don't have "harmonic current" losses since they have inductors and capacitors after the H-Bridge to create a smooth Sine wave voltage." Bill Arden

Active and passive filters do help but, some of the harmonics get past the capacitors and H-bridge to add harmonic content to the power supply. Faster switching also helps but, they are still not able to produce a smooth sine wave from pulsing DC.


Moore's law does not override the principle of Occam's Razor.

http://en.wikipedia.org/wiki/Occam's_Razor

"All other things being equal, the simplest solution is the best."

The Cycle Stop Valve is by far the simplest solution to the problems.
 

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OK, I was trying to let this thread die because it will take me a long time to explain and most people don't understand what we are talking about anyway. That is the one of the main problems. Volts to hertz ratio, sign waves, harmonic currents, switching frequencies, inductors, H bridge, even the guys who sell this stuff don't know what all that means. The average home owner is supposed to just believe that a Variable Speed Pump is a "magic" box that saves energy and therefore is worth the added expense, short life expectancy, and all the trouble that goes with it. There are lots of good applications for variable speed equipment. With fresh water pumps however, VFD's are being used as a marketing tool to get more of your money, and to be able to get more of your money, more often.

As we enter the age of electronics, we will find more and more products will benefit from switching technology. For example I was really impressed by this one 20HP motor that was the size of a car starter. In short VFD will eventually lead to smaller less expensive motors. low cost metal molding will also lead to more efficient ways of pumping (like screw compressors).

quote-"With the price of copper rising and the price of electronics falling I am going to guess that it gets to the 1hp well pump market in approximately 8 years (4*moore)" Bill Arden

Copper wire is something that will last, electronics is something that will not last. Which would you rather spend your money on? Grundfos already makes these small pumps and motors that work with "permanent magnets" and the Moore's law is how they finally got them this far. Just because a technology exist, doesn't mean that it is the best way to go..

I agree it's not the best right now, but it continues to improve while the CSV is going to stay the same.

On the other hand the CSV may end up the winner since VFD technology is likely to be integrated into the motor without any controls other than switching the power on and off.

quote-"Then look at the power draw at startup and what effect that has on other equipment. That is why I say it's generally cheaper to buy a 3 phase motor and a VFD at larger power levels." Bill Arden

Single phase motors use a lot of power at startup. However, when used with a Cycle Stop Valve there are very few startups which usually makes starting currents unimportant. At larger power levels a 3 phase motor is preferable but, it doesn't need a VFD. With submersibles you can use the longest length of the smallest wire possible to create a natural soft start. This works with single phase and three phase. The smaller wire limits the inrush currents on startup, which naturally reduces the starting torque, without needing any complicated electronics.

legislation is pushing for lower resistance windings to reduce running costs and improve efficiency.
We are already seeing the effect in the furnace market.

quote-"True "sine wave" VFD's don't have "harmonic current" losses since they have inductors and capacitors after the H-Bridge to create a smooth Sine wave voltage." Bill Arden

Active and passive filters do help but, some of the harmonics get past the capacitors and H-bridge to add harmonic content to the power supply. Faster switching also helps but, they are still not able to produce a smooth sine wave from pulsing DC.

The waveform does not have to be exact to reduce "eddy currents in the laminations". It's the high frequency edges that cause problems.
Note: These frequency's can exceed 1Mhz.

Also it is possible to create a true sine wave from pulsing DC. The power company here in MN uses a DC transmission line from ND to central MN. The DC is then converted back into AC.

On a smaller scale, The UPS I have puts out a true sine wave.

Moore's law does not override the principle of Occam's Razor.
"All other things being equal, the simplest solution is the best."
The Cycle Stop Valve is by far the simplest solution to the problems.

Agreed for now.
Give Moore 8 years and we can argue this again.
 
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Valveman

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"low cost metal molding will also lead to more efficient ways of pumping (like screw compressors)." Bill Arden

Screw compressors are positive displacement or PD. PD pumps are one of the good application for VFD's. Grundfos is already trying this with their helical style pumps. Helical style pumps were tried 40 years ago. They work great until the controls don't turn them off when they should. Then something is going to blow up. Liability was one of the reasons these pumps were taken out of production 30+ years ago. We have experienced this problem with the Grundfos pumps already. Something in the electronic controller malfunctions and the pump does not shut off when the faucets are closed, BOOM!!!


"I agree it's not the best right now, but it continues to improve while the CSV is going to stay the same." Bill Arden

I have been watching it continually improve for 30 years and it is still not right. The CSV will stay the same because there is no reason to fix something that works beautifully.


"legislation is pushing for lower resistance windings to reduce running costs and improve efficiency.
We are already seeing the effect in the furnace market." Bill Arden

That is just what we need is more government regulations. They will mandate efficiency improvements until we have to buy a new pump every year. Which will cost us a lot more and actually use more energy in manufacturing than if they would mandate making pumps and equipment last. I have heard the new heating/AC units with Variable Speed Fans use very little energy. I was told that this is because they are down for repair a lot, and therefore are not using any energy much of the time.


"The waveform does not have to be exact to reduce "eddy currents in the laminations". It's the high frequency edges that cause problems. Note: These frequency's can exceed 1Mhz." Bill Arden

High frequency edges, yep! Exceeding 1 Mhz, yep! And other Problems!!!


"Agreed for now. Give more 8 Moore years and we can argue this again." Bill Arden

I was told the same thing 20 years ago. I am still waiting. Some things mother nature just won't let Mr. Moore fix.
 
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Bill Arden

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Screw compressors are positive displacement or PD. PD pumps are one of the good application for VFD's. Grundfos is already trying this with their helical style pumps. Helical style pumps were tried 40 years ago. They work great until the controls don't turn them off when they should. Then something is going to blow up. Liability was one of the reasons these pumps were taken out of production 30+ years ago. We have experienced this problem with the Grundfos pumps already. Something in the electronic controller malfunctions and the pump does not shut off when the faucets are closed, BOOM!!!

I would expect that the T&P valve on the hot water heater would open up.
Either way a pressure release valve could be added to the pump, but that would be more cost and more things to fail.

The cost of energy is not high enough to warrant it yet.

I hope to see the day where people demand a 20 to 100 year life expectancy, but that will require a longer human life expectancy. (most people get upset after replacing something x times)

I have been watching it continually improve for 30 years and it is still not right. The CSV will stay the same because there is no reason to fix something that works beautifully.

I agree it works. Beauty is is in the eye of the beholder. ;)

I have heard the new heating/AC units with Variable Speed Fans use very little energy. I was told that this is because they are down for repair a lot, and therefore are not using any energy much of the time.
lol

"The waveform does not have to be exact to reduce "eddy currents in the laminations". It's the high frequency edges that cause problems. Note: These frequency's can exceed 1Mhz." Bill Arden

High frequency edges, yep! Exceeding 1 Mhz, yep! And other Problems!!!

New inductor materials will reduce the effects.

I was told the same thing 20 years ago. I am still waiting. Some things mother nature just won't let Mr. Moore fix.

In the last 20 years everything has improved. A new motor is smaller than a 20 year old motor due to higher purity copper.

But I see magnetic materials advancing to the point where you can make a motor that runs off of 400Hz three phase power for less money.
 

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I could grind rust or paint off steel pipe with a Dremel tool or a Bench grinder. They will both do the job. The little high speed Dremel tool is not going to last as long as the heavy duty bench grinder, I don’t care how pure the copper is.

If I purchase a $100.00 Dremel tool every year or two for 20 years, I will spend a lot more money than if I purchase a $369.00 bench grinder to last the same 20 years. I guess buying for less money is a relative thing.

Of course no offence to Dremel. I like Dremels and I use them all the time. Even if they saved 50% in energy, they would never pay out for grinding rust from steel pipe. However, they can do some things that you can’t do with a bench grinder. There are lots of good places for Dremel tools just like there are lots of good places for VFD’s. I just don’t think pumping water is one of them.
 
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