Ugh!! Water Well contractors...

[Doofy]

They spend a lot of money advertising those variable speed pumps like the SCALA. This is not because they are good for the consumer, but rather because the SCALA s the perfect "fluid" product, as it costs a lot and doesn't last long. On the false pretense of "saving energy" they trick you into the least reliable, shortest lived pump they make. Because of the complicated electronic controls in a VFD like the SCALA, they have an unbelievable failure rate. I hear from the supply houses that they are filling dumpsters with SCALA pumps that have failed. The SCALA has a worse failure rate than the MQ, which has been filling dumpsters for years. I will post a picture.

Let me say this again. Varying the speed of a compressor or any positive displacement pump can save energy. However, varying the speed of a pump with a centrifugal impeller always
causes more energy use per gallon pumped.



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Wow! I've been using one of these Grundfos pumps for 20 years and have found it to a great, trouble-free pump. My boneyard is full of old cast iron jet pumps.

 

[nknelsen]

What is the deal with water well contractors? I'm getting to the point I'd rather have all my teeth pulled without Novocain, then have to deal with another well person. No shows, poor service, deceitful, the list goes on.

The first time I ever needed my well serviced, I had a guy show up with starched pants, silver tips on his boots and smelling like a french *****. Turned out he was a bail bondsman; his brother was the actual well guy who showed late in the evening. He temporarily got me water (repaired a split drop pipe), but I could never get him out to finish replacing the pipe.

A year or so later, I got a guy out to replace the pipe, but he didn't actually have enough pipe, so some of the better original sections (which still weren't that good) had to be re-used.

The last guy was the worst. I never met a guy that got himself so twisted up in his own lies. Long story short, he replaced a 1.5HP pump with a 5HP pump that would overdraw the well in about 5 minutes of run time. His solution was to add a pump protector cut-out to cut the pump off each time the pump ran dry.

My latest predicament started almost two weeks ago, when we noticed our pressure was starting to drop. I did some troubleshooting and found the pump is drawing about half the amps and suspect either the pump has an issue or there's another split pipe. I called the well guy that everyone recommends (he's actually pretty good) and told them my issue. They said they could get to it, but it would be a few days. No problem, I can limp along a few days. It's good service to take care of those in dire need, if someone says they can get by a few days. It's now turned into almost 2 weeks and I can no longer limp along, no water pressure today. Tried calling them again and no answer now.

It's actually put me in a pretty bad position. I have an elderly parent staying with us in an in-law apartment without water, we have goat kids being born so we're hauling water from a neighbors and I was supposed to head out of town Friday.

I should change careers and start a well business.

Well contractors simply don't replace 1.5 hp pumps with 5 hp pumps. A 5hp pump is a very serious pump capable of pumping 500 plus feet of elevation.

This would be equivalent to a mechanic installing a 454 V8 into your Chevrolet to replace a 1.5 liter 4 banger. It just doesn't happen.

 

[Valveman]

Wow! I've been using one of these Grundfos pumps for 20 years and have found it to a great, trouble-free pump. My boneyard is full of old cast iron jet pumps.

Grundfos makes really good jet pumps. But they have only been making the SCALA a few years, and the MQ hasn't been around that long either. Which pump do you have?

 

[Valveman]

I was kinda thinking the energy input should equal energy output with the corresponding losses factored in.

You have to check the pump curve. This curve shows a pump drawing 10 HP load and producing 100 GPM. But when you slow the pump down with a VFD until it only requires 2HP energy, it is only pumping 8 GPM. The pump is much less efficient when the speed is reduced.

However, you should notice this same pump drops from 10HP to 3.25HP by simply restricting the flow with a valve like the CSV. The point being that a VFD is only a couple percent more than a control valve, and the control valve will cost much less and make the motor last longer instead of shorter like a VFD.

 

[Doofy]

Grundfos makes really good jet pumps. But they have only been making the SCALA a few years, and the MQ hasn't been around that long either. Which pump do you have?

Sorry, I'll have to look that up. I moved the pump out to the well box and it is -31F at the moment and I don't want to open the well box to look.

I found it cheaper and easier on the pump to push water rather than pull water and the house is much quieter with that pump out of the house. Fairly certain it is the 1hp, 115volt MQ.

 

[npalen]

You have to check the pump curve. This curve shows a pump drawing 10 HP load and producing 100 GPM. But when you slow the pump down with a VFD until it only requires 2HP energy, it is only pumping 8 GPM. The pump is much less efficient when the speed is reduced.

However, you should notice this same pump drops from 10HP to 3.25HP by simply restricting the flow with a valve like the CSV. The point being that a VFD is only a couple percent more than a control valve, and the control valve will cost much less and make the motor last longer instead of shorter like a VFD.

Interesting graph! Thanks for posting.

a VFD is only a couple percent more than a control valve What do you mean by this statement? Does this show on the graph?

 

[Valveman]

Interesting graph! Thanks for posting.

a VFD is only a couple percent more than a control valve What do you mean by this statement? Does this show on the graph?

Yes! It shows on any pump curve with a horsepower section. The curve I posted has the points marked at 1.96HP for the VFD and 3.25HP without varying the speed and simply using a CSV. Most people do not realize a 10HP centrifugal pump will drop down to only use 3.25HP worth of energy when restricted with a valve. Most people falsely think restricting with a valve will make a pump work harder. In reality the natural drop in horsepower of a centrifugal pump when restricted with a valve is only a few percent different than when slowing the RPM with a VFD.

 

[Valveman]

Sorry, I'll have to look that up. I moved the pump out to the well box and it is -31F at the moment and I don't want to open the well box to look.

I found it cheaper and easier on the pump to push water rather than pull water and the house is much quieter with that pump out of the house. Fairly certain it is the 1hp, 115volt MQ.

I have a Grundfos book from 2000 and it doesn't show the MQ. I guess they could have been around for 20 years, as time seems to fly by as I get older. But if you have an MQ that old it is the only one that has lasted that long. Most are short lived. Just search for MQ and you will find countless sad stories from people who have had a lot of problems.

 

[npalen]

Yes! It shows on any pump curve with a horsepower section. The curve I posted has the points marked at 1.96HP for the VFD and 3.25HP without varying the speed and simply using a CSV. Most people do not realize a 10HP centrifugal pump will drop down to only use 3.25HP worth of energy when restricted with a valve. Most people falsely think restricting with a valve will make a pump work harder. In reality the natural drop in horsepower of a centrifugal pump when restricted with a valve is only a few percent different than when slowing the RPM with a VFD.

So did you mean "a couple horsepower" rather than "a couple percent" difference between VFD and CSV at the reduced flow?

 

[Valveman]

So did you mean "a couple horsepower" rather than "a couple percent" difference between VFD and CSV at the reduced flow?

It depends on the particular pump and where you look on the curve. At low flow most pumps are 7% tp 10% different between variable speed and a simple valve. At high flow the control valve is usually 3% to 5% better. Overall the difference is probably only "a couple percent". I was using a 10HP just to make the numbers easy. It would certainly not be much difference with a 1HP pump.