grundfos cu301 for irrigation--VFD? CSV? Homeowner at wit's end

[gardenerDC]

Quick background. I'm a homeowner with a large garden. We struck water when digging wells for our geothermal heating system. Checked the flow, it was good and had a pump installed. The well water (that pump works fine) gets pumped to an in-ground storage tank. In the storage tank is a booster pump which feeds our irrigation system. That pump is controlled by a Grundfos CU301. This is at least Year 3, perhaps 4--we've had nothing but problems. To be fair, not all of the problems can be attributed to the CU301, just most of them. The well company has been out three times this season, two of which were related to the CU301. For me, the biggest frustration is not being able to handle basic problems. For example, Saturday the system worked just fine. Sunday I noticed that the pump indicator was running continuously. The irrigation was off--no water was being called for. However even when I tried turning the irrigation on, it wouldn't deliver any water. Tried "rebooting" it by turning the power off for a few minutes. No luck. Today, rather than make another $200 service call I decided to troubleshoot it myself. I got out the manual, checked basic indicators outside the box then opened the box and to check the LED indicators. Everything looked right--greens in the right places, except I had a solid yellow on the Max speed. I'm guessing this has something to do with a dry run--it has shut off before from this. (As I said, the pump supplying water to the storage tank works fine but after a ground lightening strike fried something it wouldn't fill!). When I saw the indicator running constantly on Sunday I also noticed that the well pump was refilling the storage tank (after the small amount used on Saturday, it should have replenished the tank pretty quickly.) So this made me suspicious about a dry run. Then I read that the pump speeds up as power and pressure go down when the water gets low, which supports that suspicion perhaps? Maybe I didn't notice the dry run indicator was on the other day and it went off after my reboot? So what to do and how to fix it? As my husband now does regularly, head for the internet! Before I could even find my specific problem, I got sidetracked by the multitudes of posts about endless problems with the CU301 and the debate over VFD and CSV. I now understand that issue as much as any intelligent person can absorb in 30 minutes, which is to say the basics of the debate and opinions seem as polarized as this November's election! I did notice, however, that many of the posts were several years old--has there been progress on this front?

So I have an immediate question: Can I get my pump running again without a tech given the yellow Max light indicator and the continuous running and without the handheld R100 to "talk" to it? And I have a big picture question: Do we fall into this VFD/CSV debate and how do we determine what is the right approach for our system? I need a system that I know is going to work. And on those occasions when something does go wrong, I don't want it to be so opaque that I have no choice but to pick up the phone. When we leave 100 degree heat in DC for vacation, I have to know that the system isn't going to lock out which it has done time and again. Fortunately, when we installed the system originally, we also installed a city water valve. Sadly we've had to run it too often on city water because we simply couldn't be sure the well system would work. So much for "free" water...

[valveman]

Here is another old one.
http://www.cyclestopvalves.com/csvapplications_21.html

But notice how many of those old ones that switched from VFD to a CSV have never come back with a complaint. As a matter of fact they haven’t come back to a pump forum since, because they no longer even think about their water system. That is the way it should be. Your water should be so dependable that your neighbors on city water should need to borrow from you more than you from them. Simple is what makes it dependable.

[gardenerDC]

Thanks for the response and also for including that link to the other thread. We've learned so much from others who take the time to walk through problems they've solved just to help other people in similar situations. Truly one of the great things about the internet. I'm waiting to hear from my well guy to see if he can walk me through via phone how to get my 301 back running. Beyond that, however, I'm going to press hard on the CSV alternative. Not to mention that what I've read about the life span of the 301, it's not likely to last long anyway.

Unfortunately I've had no luck finding any internet video or how-to advice on how to restart the 301 when I've hit Maximum Speed yellow. If you or anyone knows a link, that'd be great.

[valveman]

That pump will work without the CU301 controller. Just remove the CU301 and install a regular 40/60 pressure switch. The pump will cycle on and off instead of varying the speed to stay running. But that is what it has been doing for a while anyway. Anytime the CU301 loses communication with the electronics in the motor, it reverts to acting like a pressure switch and cycles the pump on and off. The newest version will cycle the pump on and off 1,000 times before it even shows a fault.

The pressure switch will get it back to running and get your water flowing. Then you can either add a large pressure tank and let the pump keep cycling on and off, or you can install a CSV to get the constant pressure you are use to, without all the problems that go with varying the pump speed as with the CU301.

Your pump man is not going to be happy that you are asking for a CSV. Just look at how much money he has made with that SQE/CU301 so far. Installing a CSV, which could make everything last 20 years without so much as a service call, is going to cut him out of a lot of profit.

Before the Internet, people just had to take the word of their pump man. Now I find that many homeowners are more informed than many so called “professionals” in the pump industry. People just need to inform themselves before they get stuck with something like the SQE or CU301. You have already spent as much on that system as the pump man would have received from a good pump system in 30 years. At this point it is much like closing the barn door after the horse is already out. The sooner you get away from that Tar Baby the better off you will be.

[bcpumpguy]

Drives can be nice, in an industrial setting where very specific process controls are needed. As a pump installer, I'd quit my job if i had to install grundfoss products especially their drives. I used to like drives, more and more i am starting to like CSV's, however if a person wanted to go with a constant pressure drive system, i'd stay as far away from grundfoss as possible.

[Porky]

Go with a CSV and your water system problems will be over. Try it "I promise you'll like it"!

[Joshua Talley]

So I have an immediate question: Can I get my pump running again without a tech given the yellow Max light indicator and the continuous running and without the handheld R100 to "talk" to it? And I have a big picture question: Do we fall into this VFD/CSV debate and how do we determine what is the right approach for our system? I need a system that I know is going to work. And on those occasions when something does go wrong, I don't want it to be so opaque that I have no choice but to pick up the phone. When we leave 100 degree heat in DC for vacation, I have to know that the system isn't going to lock out which it has done time and again. Fortunately, when we installed the system originally, we also installed a city water valve. Sadly we've had to run it too often on city water because we simply couldn't be sure the well system would work. So much for "free" water...

Hi,

I work for Grundfos, so I may be able to answer your question.

First of all, I'm sorry you've had so many troubles with the system... I get annoyed when my stuff doesn't work the way I expect.

We have had issues with the SQE+CU301 systems in the past, but for the last few, we believe we've worked out most of the bugs, so that whatever the 301 reports should be an accurate display of what is happening. having the R100 available to use would certainly give you more information, but based on what you've said so far, I have a rough idea of what may be happening. The "booster pump" should be one of our SQE models (e.g. 10SQE05C-160).

The "MAX SPEED" light simply means that the pump is running at the maximum speed. It doesn't mean there's an error or a problem, necessarily, just that it's running as fast as it can. Dry run is different. That means that the pump thinks there isn't any water. Dry run is triggered by a few factors, namely max speed & current draw. If the motor is running at max, and the current draw is lower than expected, it means there's no load on the motor, which is either no water (more likely) or the pump shaft is broken (not likely). You mentioned that a lightning strike affected the well pump, so if that pump doesn't fill the tank where the SQE pump is located, you'll be getting lots of those errors. Enough of them in succession, and the pump will shut itself off for a time in order to protect itself from damage.

As valveman pointed out, you could disconnect the CU301 and replace it with a pressure switch if you want. The pump will then act like a typical submersible pump, just with the added feature of dry run protection. But again, if the problem is low water in the tank, then a switch won't make the issue disappear.

Regarding the VFD vs. CSV debate: the primary benefit of the VFD (built into the pump in this case) is energy efficiency, along with additional benefits like constant pressure and monitoring conditions. Compared to a CSV, if all is running well, you'll have lower electrical bills and extended life of the pump. Using a CSV or any type of throttling valve on a fixed-speed pump is akin to putting the pedal to the metal while pressing the brake to limit the speed: you have constant performance at excessive energy and component cost.


Hopefully this points you in a good direction. I'd be glad to help you more.

[LLigetfa]

Regarding the VFD vs. CSV debate: the primary benefit of the VFD (built into the pump in this case) is energy efficiency, along with additional benefits like constant pressure and monitoring conditions. Compared to a CSV, if all is running well, you'll have lower electrical bills and extended life of the pump. Using a CSV or any type of throttling valve on a fixed-speed pump is akin to putting the pedal to the metal while pressing the brake to limit the speed: you have constant performance at excessive energy and component cost...

Wait... lemme get some popcorn... gotta love that FUD.

[Joshua Talley]

Wait... lemme get some popcorn... gotta love that FUD.

Hyperbole, perhaps, but the results are well known. I'm not a fan of FUD-slingers, so I certainly don't intend to be one myself.

[Texas Wellman]

In before the lock, popcorn ready.

Hyperbole, perhaps, but the results are well known. I'm not a fan of FUD-slingers, so I certainly don't intend to be one myself.

[craigpump]

Gets a Pepsi, sits back, puts feet up and waits............................

[Porky]

As i've said before

Go with a CSV and your water system problems will be over. Try it "I promise you'll like it"!

[valveman]

This subject is complicated enough. Normally I would just delete inaccurate statements. In this case I think it is good for everyone to see what companies like Grundfos teach their young salespersons to say, in order to con people into their most profitable and least dependable products.

“We have had issues with the SQE+CU301 systems in the past, but for the last few, we believe we've worked out most of the bugs,”

This is the same thing you will hear from every VFD manufacturer. In the past 12 or 13 years that the SQE has existed, I believe there have been at least six “upgrades” so far. With every “upgrade” or “new generation” they will say they have “solved the issues”. However, the side effects of PWM or Pulse Width Modulation, which is used to vary the motor/pump speed, cannot be “worked out”. These “issues” cannot be “solved” unless you can change the laws of physics. New “upgrades” or “generations” have been able to limit, but can never eliminate voltage spikes, harmonics, resonance frequencies, bearing currents, and other side effects of Variable Frequency Drives, also known as “VFD’s, VSD’s, Freq Drives, Constant Pressure Pumps, and many other names.

Even if solving the problems of VFD’s were possible, manufacturers would not want it. The VFD is the perfect tool for “planned obsolescence”. Why would they want to change
something that is expensive, doesn’t last very long, not repairable, and provides your drinking water, so it must be replaced quickly, without having time for you to consider other options. Being such a complicated subject they can make you think a simple drop in amps is “saving energy” is just icing on the cake.

“Regarding the VFD vs. CSV debate: the primary benefit of the VFD (built into the pump in this case) is energy efficiency, along with additional benefits like constant pressure and monitoring conditions. Compared to a CSV, if all is running well, you'll have lower electrical bills and extended life of the pump. Using a CSV or any type of throttling valve on a fixed-speed pump is akin to putting the pedal to the metal while pressing the brake to limit the speed: you have constant performance at excessive energy and component cost.”

This statement must be in the Grundfos employee handbook. All new hires must be required to memorize this false statement to qualify and work at Grundfos. The following link from a Grundfos memo in 2005 explains all the problems with the above statement. The pump curves were provided by Grundfos, not me.

http://www.cyclestopvalves.com/pdf/pumpman_3.pdf

I started selling Grundfos pumps in 1973, and have been working with VFD’s for more than 25 years. From your picture I don’t think you are even that old. Hopefully this points you in a good direction. I'd be glad to help you more if you really want to know the facts. However, Christmas is never the same after you find out Santa Claus isn’t real.

“Lets all go to the lobby for refreshments.”

[bcpumpguy]

Hi Valveman,

I'd like you to expand on the problems of VFD's tell me about the side-effects of pwm and what issues you really have with VFD's. Don't get me wrong I like CSV's very much, but there is applications for VFD's where they can be exploited quite well.

I read the Grundfoss memo, i stopped where he calculate hp ratings for the vfd and csv at the same gpm but diffrent feet of head.

[valveman]

Hi Valveman,

I'd like you to expand on the problems of VFD's tell me about the side-effects of pwm and what issues you really have with VFD's. Don't get me wrong I like CSV's very much, but there is applications for VFD's where they can be exploited quite well.

I read the Grundfoss memo, i stopped where he calculate hp ratings for the vfd and csv at the same gpm but diffrent feet of head.

Don’t get ME wrong. I believe there are some good applications for a VFD. VFD’s have benefits when used on conveyor belts, escalators, compressors, even sewage or transfer pumps. However, VFD’s are not good for pumps that must buck a static head or deliver constant pressure. A VFD maybe able to save energy on pump systems where the pressure required can be reduced part of the time, but this is not the case with well and booster pumps. If a well is 200’ deep, the pump will always have to produce 200’ of head. If the pump has to deliver 50 PSI to the house, using a VFD to lower the pressure to 20 PSI is not an option. You can’t make a well more shallow, or lower the pressure and get the washing machine to fill like it should. So the head or pressure cannot be lowered as required for a VFD to be able to save energy.

Like I said, it is such a complicated subject that even the engineers for the pump manufacturers don’t understand what they are talking about. They claim I don’t know how to figure wire to water efficiency, even though I was doing those calculations when I was 13 years old. I claim they don’t understand the Affinity Laws only work at two points in the curve where the pump has the same efficiency. I also claim they go straight to the third Affinity Law showing horsepower decreasing by the cube of the speed, and skip right over the second Affinity Law. The second Affinity Law is the most important, because it shows the head being reduced by the square of the speed.

The minimum pump speed that will still produce water at the head or pressure required must be maintained according to the second Affinity Law. Only then can the third Affinity Law be used to figure the lowest horsepower possible. Doing this the other way around makes the VFD look like it is saving a lot of energy, but also means the pump isn’t spinning fast enough to get water out of the well, much less build any pressure.

Just look at the pump curve. It doesn’t matter that the head is different for the CSV and VFD. What matters is the horsepower at a given flow rate. I couldn’t believe that Grundfos provided pump curves in their article about CSV’s. It is hard to manipulate the calculations to fit the way they want when the pump curve is provided to prove otherwise. Just look at the last pump curve in the letter from Grundfos. It shows the bhp or Brake Horsepower for all flow rates.

Even with the pump always spinning at 3450 RPM using a CSV, the horsepower drops from 10 HP at 120 GPM to 3.25 HP at 5 GPM. Using a VFD to slow the pump speed down to 2886 RPM, the horsepower only drops from 10 to 1.96HP. The CSV reduces the horsepower by 67.5% from 10 to 3.25 HP, while the VFD reduces the horsepower by 80.04% from 10 to 1.96 HP. That means the pump with the CSV is only using 12.5% more energy (about $3 per day) than with the VFD at the lowest possible flow rate.

Now go to the other end of the curve and you will see that the pump is using 10 HP to produce 120 GPM with the VFD or the CSV. But not shown on the curve are the loss of motor efficiency at reduced speed, loss of motor efficiency for running on the pulsing DC voltage with harmonic content, and the parasitic losses for the energy the VFD itself is using. This can add back 5% to 7% more energy used with the VFD, especially at maximum flow rate. None of these losses are applicable when using a CSV in the wide-open position. Which means the VFD system is using (about $3 per day) more energy at high flow than a CSV system. At low flow the VFD is doing better by $3 a day, at high flow the CSV does better by 3$ a day. So if half the day is at low flow and the other half at high flow, there is no difference in energy consumption between a CSV and a VFD system. The CSV is certainly not “like driving a car with one foot on the gas and one on the brake”, as VFD salespersons would like for you to believe.

Also look at the lowest flow rate and the horsepower required compared to running at maximum flow. A VFD using 10.7 HP to produce 120 GPM is 11.2 gallons per horsepower. Slowing the pump down with a VFD shows to use 1.96 HP, but is only producing 5 GPM. That is only 2.55 gallons per horsepower compared to 11.2 gallons per horsepower at max flow. Slowing the pump down with a VFD is causing over 4 times or 440% more energy used per gallon. How can anyone claim a VFD is “saving energy” when it actually causes 440% more energy to be used? They just show the amp drop and say, “look at all the energy the VFD is saving”. But the great and powerful Oz says, “pay no attention to the flow meter behind the curtain”.

As for other issues I have with VFD’s, I will finish with a couple of links with hours of technical reasons to read. But the main issue I have is the VFD is being used for “planned obsolescence” like a plastic timing gear in a car engine. They can advertise that their car or pump is being built with the highest quality components, to outlast all other cars or pumps. But adding that plastic timing gear to the car or a VFD to the pump, means you are going to need a new car in less than 100,000 miles or a new pump in a short period of time, no matter how good it looks or how much quality you thought you were buying.

I read yesterday that Franklin paid 25M and purchased the VFD manufacturer Cerus. So Franklin will now be making their own VFD’s. Do you think they would spend that much and make their own VFD’s if it was going to save the consumer money? As I have said many times, if you want to know what makes pump companies the most profit, look at what they are pushing and advertising. Just remember that pump manufacturer profits come directly out of the consumer pocket.

I am not one that thinks corporate profits are evil. Because of good marketing I will probably pay more for a Coke than an off brand cola. But Coke isn’t lying to me about their product making me stronger, taller, or smarter, the way VFD companies are lying about saving energy.

Sorry for the long post. As simple as I could explain it took two pages. So you can see why the average person is confused and just throws the credit card down several times before they start researching and discover all the problems with VFD’s.

http://www.cyclestopvalves.com/vfd-energy.html
http://www.cyclestopvalves.com/csv-vs-vfd.html