# Cycle Stop Valve

Discussion in 'Open Loop' started by ldameron, Mar 4, 2009.

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Correct. It might be easier if you strip away the time factor
and look at it in terms of total gallons pumped per kWh.

At 100% efficiency, you pump 318167 gal-ftwc per kWh,
(ftwc is just delta-P across the pump expressed in weird
pressure units: 1 foot-of-water-column = 0.4335 PSI).
Density, viscosity, and direction (i.e., up/down/sideways)
make no difference ... energy = volume * delta-P

At 220' head, 100% efficiency yields 1446 gal/kWh

At 260' head, 100% efficiency yields 1224 gal/kWh

Multiply by efficiency to get the actual gallons/kWh.

In general, there's no way to predict whether throttling
the output will increase or decrease pump efficiency,
but the smart punter would bet on increased \$\$/gal.

Looby

2. ### RancherNew Member

Ronald, I could only find message #13 and message #71 which were 10 and 12 times an hour for pump cycling.

The question is: If the heat pump cycles 10 times per hour, the pump witll probably cycle 10 times per hour with or without the CSV.

Rancher

4. ### ncgeoMember

Rancher, you are right with the CSV the pump will cycle in sync with the heat pump, with some small delay at the start and lag at the end But without the CSV the pump cycles multiple times per heat pump cycle. Fortunately I don't have an issue with my heat pump cycling 10 times per hour. I that were the case I would have other issues to address as well(oversize heat pump, poor insulation, etc). And like you said I would not need the CSV, since with the 25 gal drawdown of the current setup the pump would only cycle once per heat pump cycle

I saw that link to the electric meter, but that won't necessarily help. For instance if I ran a 1 hr. test cycle with current setup and measured power, I would need to run the EXACT same test cycle with CSV. I guess I could do that by forcing the heat pumps to run constantly during that hour test. But because power consumption is directly related to amp draw (P = V * A * some efficiency/power factor values) I can also just measure current, everything else in the equation is staying the same. Then knowing the well pump will run 70% longer with CSV (going from 60% duty cycle to 100%) I can calculate power consumption. Or at least the relative increase or decrease in power consumption if I don't have all of the values for the formula (I don't have efficiency and power factor).

As mentioned earlier I do want to firm up the duty cycle figure by timing the pump operation again. If the duty cycle is actually 75% instead of 60% I'll be off by 25% (the 15% increase in duty cycle is 25% of 60%). That is the key here; how much LONGER the pump will run with CSV.

Complicating the matter more there are periods of time when only one heat pump is running. During that time the duty cycle is less (the tank will refill quicker and take longer to drain. I should get timings and current readings for those operating scenarios before and after CSV.

Because I already have a large tank setup and the heat pump does not always run full bore for hours at a time, my situation is probably marginal for any savings with a CSV. But since I'm a techie who loves getting his hands dirty, I'm chalking this up to a learning experience no matter the outcome. I'm sure you heard, no free lessons in life.

In fact the more I look at the pump curves I could be running a 1/2 HP - 8 GPM pump to serve my needs. For the short periods of time when my future irrigation runs with both heat pumps running the pump will have trouble keeping up. But since irrigation is generally done in the AM that is not a likely scenario.

Some will suggest I should have called a pump guy before spec'ing and buying the pump. I did; he suggested a 1.5 HP for geothermal systems. Sigh.

5. ### ValvemanGuest

I think this "duty cycle" thing has some people confused. We have a 12 GPM pump, running 9 GPM to the heat pump, and cycling into an 86 gallon tank, which hold 23 gallons at 40/60. This means we are filling the tank at 3 GPM, which takes 7 minutes and 40 seconds. Then we are draining the tank at 9 GPM, which takes 2 minutes and 30 seconds. 460 seconds on, and 150 seconds off, gives a run time of 75%, and off time 25%. I would call this a 75% duty cycle because the pump is running 75% of the time. This should be about 6 full cycles per hour, 144 cycles per day, 4,320 cycles per month, and 52,560 cycles per year.

If your pump is cycling more than 6 times per hour, then the pump is delivering more than 12 GPM, the tank is not holding 23 gallons as it should, or both. 10 cycles per hour is 87,600 cycles per year.

When used with a Cycle Stop Valve the pump will run 100% of the time when the heat pump is on. This is running the pump 25% longer than before, yet using about 20% less than full load. (Figured with Horse Power equation) This should account for about a 5% increase in the electric bill.

There will also be some energy reduction from eliminating multiple start ups. It takes about 6 times the running amperage to start a pump. Most of these high inrush currents will be eliminated as the CSV will keep the pump running continuously. These inrush currents do not last very long but, they add up when the pump cycles a lot. With a 75% duty cycle and a 20% decrease in energy, considering the elimination of multiple starts, I would be surprised if there is any increase in the electric bill, and there may even be a decrease.

Whether the electric bill goes up or down a couple of dollars a month is going to be inconsequential, compared to eliminating 52,560 or 87,600 cycle per year. Cycling is the number one reason for premature failure of pump systems. Eliminating 50,000 to 80,000 cycles per year is going to increase the life of the pump by a factor of 3 or 4 times. This is where the real savings come into play.

Being "green" is less about saving a couple of bucks a month on the electric bill, than it is about getting the longest possible life out of expensive pumping equipment.

7. ### RancherNew Member

Smoke and Mirrors

I'll bet Valveman even has a platinum gas saver installed on his pickup truck.

Now how again did we eliminate these cycles... is the pump running full time now? I'm confused, I thought we determined that the heat pump was cycling...

I'm sure you have real study that supports this claim.

If it was just a few bucks, I would agree with you, however in the Amtrol test it was 2.5 time the power consumed, not the 5% you quote.

http://www.amtrol.com/pdf/jlanearticle.pdf

Page 3 Table 2.

Is everybody confused with Valveman's numbers?

Rancher

8. ### ValvemanGuest

For most people, you don't need a study for something that is just common sense.

If anybody is confused, it is because Rancher is trying to confuse you. He keeps showing that Amtrol article like a tank manufacturer is going to tell you that you no longer need big pressure tanks. Joe Lane (the author) no longer has that article on his web page, because it was making them look foolish. Look closely at the Kwh/day. You will see that it went from .5 Kwh/day to 1.25 Kwh/day. At 10 cents a Kilowatt, that is a whopping difference of \$2.10 per month. That test was also set up to make pressure tanks look better than anything else. Go fugure!! There was only 300 gallons per day being used, and never any water demand more than 7 minutes at a time. This was the same way Rancher set his system up to make the CSV look bad.

There is a big difference between that system, and one that uses more than 300 gallons per day, and has water being used more than 7 minutes at a time. There is a huge difference between that system and one where the pump is already running 60% or 70% of the time.

Just in case anyone here can’t see the unjustified vindictiveness in Ranchers comments, here are a couple of links for you. I have been dealing with this for several years now.

Cycle Stop Valve Truth - Topix

Pumps And Tanks Forums! - New Virus Alert

9. ### ncgeoMember

Good article, considering the source, and it shows there are other ways to minimize pump cycling for typical household use (NOT geothermal). But I don't think a 20 or even a 36 gal is sufficient to match pump cycling of CSV. A typical 10 minute shower is 30 gallons. With an 86 gal you would probably cycle LESS than a CSV on typical household chores. But the costs get prohibitive with the larger tanks.

If there were some reasonably-priced setup with like 75 gallon of drawdown that probably would have worked for my geo.

Do you want to spend money on CSV + additional electric (still a question)? Or large/massive tank? Either way you save your pump.

Well drillers can tell you where they get 120-250 gallon well water tanks...most with bladders so they don't waterlog. In Texas, they bury them in the yard...no freezing issues. It won't work in Ohio or places North.
Remember you water usage is about 30% of the total volume.

11. ### ValvemanGuest

You are correct. The pump is running only 25% more of the "time" but, that is 33% more than it is now. I stand corrected. Thanks

Which is it

You say it's "common sense", yet you have also said it's "counter Intuitive".
It can't be both!

Bergy

"Ninety percent of this game is half mental."
- Yogi Berra

.

14. ### ValvemanGuest

As I said, the only thing I know of that is truely "counter inuitive" is that work and load on a pump is easier when it is restricted or throttled back with a valve.

The fact that reducing the number of cycles per year by 50,000 to 80,000 times is going to increase the life of your pump system, is "common sense".

Both of these things have been common knowledge to many of us in the pump business since 1993.

15. ### RancherNew Member

Figures can lie, liers can figure

The 50,000 to 80,000 times a year figure came from the maximum number of cycles the pump will make without a CSV, saving that many cycles means the pump is running full time, which of course it won't... It will cycle once everytime the Heat Pump comes on, my heat pump cycles 10 times an hour, so that's 10 x 12 x 365 = 87,600... so exactly where is the savings?

Do the math folks, valveman is just trying to baffle you with BS.

Rancher

16. ### ncgeoMember

The cycles do sound on the high side but it would depend on your consumption, production, and tank size.

Man if my heat pump cycled 10 times an hour I would be looking at that as well. That tells me you getting a blast of hot/cold air which is quickly dissipating.

17. ### ValvemanGuest

OMG!! So you are effectively cycling everything you have to death! A well pump can't take that kind of cycling, I don't see how a heat pump can either.

Quote from Private Message.
"Cary, think about it, I could invade every forum and cause you a world of hurt, I could do it from multiple IP addresses, and multiple user names.

Knowing how to do that and how to defend the nations networks are what I do for a day job.

John (aka Rancher)"

Cycle Stop Valve Truth - Topix

Pumps And Tanks Forums! - New Virus Alert

18. ### RancherNew Member

I was only talking my heat pump, remember I have a DX system. So 10 may be kinda high but at least a cycle every 10 minutes, 6 cycles per hour. I asked how often your heat pump cycled, but never got an answer.

Rancher

19. ### RancherNew Member

Valveman, are you making stuff up again? Please tell the people what forum this is posted in so they can check for themselves.

Rancher

20. ### ncgeoMember

Assuming my thermostat setting is constant I would say my heat pumps never cycle more than 5X/hour . Its on for a good 6 minutes minimum, then off 6 ...