Cycle Stop Valve (Example)

This is a very large pump system but, that makes it easy to see the details. This system was installed in Marion County Florida. A 4" CSV and the 80 gallon bladder tank replaced a 12,000 gallon pressure tank. The pressure recording chart shows that the five days before the CSV was installed, the pump system cycled on and off 291 times. That would mean it turned on and off 57 times per day, 1710 times per month, or about 21,000 times per year.

You can see that the pressure is constantly varying between 52 PSI and 74 PSI. This not only annoying for continually varying the pressure in everyone's home but, causes water hammer on the entire system as well. This amount of cycling will also cause early destruction of the pump system itself.

You can see that for the 2 days after the CSV was installed, the pressure maintained almost exactly 60 PSI constant. The pressure dropped a little during times of peak demand, as that is all the pressure the pump could produce at such a high flow rate. Other wise the pressure remained constant, water hammer was eliminated, and 21,000 cycles per year are also eliminated.

We are hoping to soon have some idea of the difference in power consumption on this system. This will compare the power used for the pump cycling all the time at high amperage, to the power used while the pump runs all the time at lower amperage with the CSV. However, even if this big pump uses $200 more power per month using the CSV, it has eliminated a $75,000 pressure tank. That means it would take 31 years to save enough energy to pay for the big pressure tank. Then if you consider that eliminating the cycling will make the pump system last twice as long as when cycling, the pay off for the big pressure tank will be even longer than 31 years.

The same thing happens on smaller pump systems for individual houses. The difference is only in scale. On a house system, if the CSV cost an extra $2 per month in the electric bill, it also eliminates the need for a $500 pressure tank. In most cases the CSV will cause the electric bill to be lower but, even in worst case scenarios, the CSV will save more in equipment cost than you could ever save with a big pressure tank.

Its funny looking at that giant tank outside exposed to the elements. I used to wire pump stations for a living but up here in the north the tanks either have to be buried or inside a building to prevent freezing.

Also it was always multiple 3 phase VSDs for power and control. Probably because thats all the design firm we worked with knew how to do.

CSV1Z homeowner example

First, the 12,000 gallon tank is shut off but, that would not matter. With the CSV, as long as more than 5 GPM is being used, the pump will never shut off, not mater the size of tank.

Second, yes the air charge in the 12,000 gallon tank was correct. It has an air compressor and probes to make sure.

Third, the pump was not changed. It is the same 400 GPM pump that was cycling itself to death with the 12,000 gallon tank. I believe it is a 30 HP but, this is a system that was recently picked up by the County, and I don't think anybody knows the pump model number.

Forth, I believe there is another pump in this system. However, it was turned off during this time so this pump was handling the entire load. It will always use more electricity when you have a 30 HP pump trying to do a 10 HP job, and the same thing is true when using Variable Frequency Drives. This example was just to show that one big pump using a CSV can do any flow rate that is needed without much increase in power consumption. Although, most large systems using Cycle Stop Valves will have two or more pumps. In this case, using a 10 HP and a 30 HP in combination, will allow the system to be efficient when as little as 5 HP water is needed to when as much as 40 HP water is needed. When only 5 HP water is needed, the CSV throttles the 10 HP to use only 5 HP worth of electricity. When 40 HP water is needed, both pumps run at the same time.

We have some power consumption test being done now. When we get the results I will let you know. However, as I said before, there would have to be a lot of energy saved to be able to afford the $75,000 pressure tank, as well as replace the pump system more often because of all the cycling with the big tank.

The $75,000 tank and all the maintenance that goes with it have been eliminated. The reduction in cycling will make the pump system last three times longer than normal. The "constant pressure" eliminates line breaks and the water wasted because of it. Using multiple pumps will make the system as efficient as any other way of doing the job. It would be kind of hard to make any of this look like a bad thing.

There were about 9 of these systems installed at the same time. I am sure we will get some more data for you to look at very soon.

Drick, thanks for your comments. Most engineers can sort of understand how a VFD works. It takes someone who really understands pumps to realize that throttling with a CSV will accomplish the same thing as a VFD. Only the CSV does not have all the side effects, nuisance trips, and extra cost of the VFD.

Jluksic, thanks for the picture.

Hello valveman

Could you please explain the main differences/ features and benefits with a CSV vs. a VFD.

I am interested in the residential market. We will typically see a 40/60 pressure switch and holding tank. In some very large homes, a VFD is requested so that the pressure it is constant in the home. I understand these pumps are always turning and is accomplished through electronics ... what are the drawbacks that you keep mentioning?

From what I have read it appears a CSV accomplishes the same thing but is purely mechanical. Is there a drawback here?

Thanks for enlightening me.

Thanks for asking 99k. Here is a link to more details. Also glad to talk about it any time.

http://www.cyclestopvalves.com/comparisons.html

99k said:

Could you please explain the main differences/ features and benefits with a CSV vs. a VFD.

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There was a debate earlier on this forum.

The net result was that the CSV is a better option in smaller systems.

Using a CSV on a large system is questionable due to the energy used and the cost of the pump, however by using a second smaller pump there is a chance that the CSV would come out on top.

We should revive that other thread and not clutter this one with VFD talk.

>$75,000 tank

But you won't be able to sell the used tank for that, so the figure is only valid if the tank was at a point where it needed to be replaced.

valveman said:

Thanks for asking 99k. Here is a link to more details. Also glad to talk about it any time.

http://www.cyclestopvalves.com/comparisons.html

Click to expand...

Thanks. That's a lot of good information.

Let me run a scenario by you, perhaps it is somewhere on your website, but I want to make sure I understand a residential application.

There are customers of very large homes in our area ( i.e. 10 bathrooms, etc) who want "constant pressure" anywhere in the house. What they really want is MAXIMUM pressure at all times without the drop-off associated with the tank drawing down. The traditionial setup is a well pressure tank with a 40/60 switch.


Thanks for your comments.

Hi 99K. As you said, the customer wants MAXIMUM pressure all the time. Someone who has 10 bathrooms is not going to complain about an extra $10 per month electric bill but, they will complain about low pressure in any of the bathrooms.

I understand (all too well) the problem of the pressure fluctuating for 40 to 60 all the time. Not only is this not enjoyable when using water but, will also cycle the pump to death in short order.

With the CSV, the pump does not run “all the time”. The pump only starts after the pressure tank is empty, then it only continues running when there is a certain amount of flow being used. When no water is being used, the CSV refills the pressure tank, and the pump is shut off. To maintain 60 PSI constant in the bathrooms and house, you just need a 60 PSI Cycle Stop Valve. Then used in conjunction with a pressure tank, a pressure switch would be set to start the pump at 50 and off at 70 PSI. The smaller the pressure tank used, the sooner the pump is on and the pressure is at a constant 60 PSI. The larger the pressure tank, the less times the pump must start for intermittent uses such as ice makers and washing toothbrushes. A compromise in tank size, gives the best of both worlds. Used with a pressure tank that holds 5 gallons of water, the pump will not come on until after three flushes with 1.6 gallon flushers, or a couple of weeks of the ice maker working. However, with only 5 gallons in the pressure tank, the pump will be on and the pressure at a constant 60 PSI, before the water temperature in the shower is adjusted to suit the bather. Then as long as the pump is large enough, the pressure will remain at 60 PSI constant even if 10 showers are on at the same time. See this quote from a CSV user who understands the benefits of “constant pressure”.

scotch12 said:

I installed a CSV1Z 3 years ago to prevent well pump cycling during lawn irrigation. My sprinkler system irrigates ~6000 square feet (6+ zones) and delivers ~7GPM over a 80 minute run time, 3-4 days a week.

The pressure switch is set at 40-60psi. Bladder tank pressure at ~38psi. Original 14 year old Red Jacket submersible and

Yield (gal/min) 12
Depth (feet) 298
Level (feet) 70

CSV1Z installation took about an hour. Fine tuning the CSV took about 15 minutes.

We consume ~115,000 gallons per year for a family of 4. Majority of water consumption during short summer.

The CSV works PERFECTLY. On demand, the well pump will kick in at 40psi, build pressure until the CSV1Z set point (56psi) and hold 56psi for the duration of the lawn irrigation, including between zone changes.

Added benefit is during long showers water pressure is constant 56psi.

If you're on a well system and lawn irrigate regularly, the CSV make perfect sense.

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Thank you valveman for explaining the system and the example ... I now understand how this works. One last question, on a retro then I would presume that the large pressure tank needs to be replaced (albeit it still is good shape) and replaced with a much smaller one along with the CSV.

Thanks,

Ken

99K, if you already have a large pressure tank, you don't really need to replace it with a smaller one. You can get a pressure switch that will let you do 10 PSI between on and off. Then you can set the on at 55, off at 65, and the CSV at 60. The larger tank will actually let you have more draw down with the narrower pressure switch band width. With this pressure setting, the people will probably never be able to see any difference in pressure.

Thanks for taking the time to explain Valveman