To CSV or Not to CSV, That is the question.

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superdavet

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This post is from a conversation I initiated with 5 other members. I received good replies with some points to ponder, but thought I would re-post my original post in it's entirety. I would also appreciate any feed back from well owners who are using a stop valve system, how it is working for you, as well as owners of "conventional" well systems and why or why you chose to stick with a "conventional" setup.

Thanks, dave.


Good day. I am weighing a stop valve system vs. a conventional pressure tank and switch. I know this topic has been covered quite extensively over the last few years and I have been following it off and on for the last 2. I am now finally ready to make a decision, but find that there seems to be some missing pieces to the puzzle for me to make as informed a decision as possible. I was all set to go with a stop valve system when an on-line retailer said they did not recommend a stop valve system for residential purposes. So I started delving into the subject even more than before.
There seems to be differing opinions as to the worth of stop valves compared to properly sized pressure tanks.
1) I have heard that stop valve systems are suited for mainly irrigation purposes, and for other higher usage, variable flow requirements, stop valves seem to be a good way to go. But for normal everyday residential applications, I have begun to question the viability of stop valves. I understand that during showers it’s heads and shoulders, (no pun intended), above standard pressure tanks because of the higher and more consistent flow rate, but that isn’t what the main draw is from a well. Typically with a family of 4, there will be say , 4 showers a day, but after that, consumption is mostly on/off, on/off of sinks, toilets, dishwasher etc etc. Given the smaller pressure tank with a stop valve, will the pump not cycle on and off even more often with a stop valve/pressure tank compared to a properly sized tank due to the small pressure tank cycle volume?

here is a post from another forum that I found interesting...(edited for content).

“I'll jump on this one. Cycle stop valves have been around for a very long time now. The concept is nothing new at all and you have to ask yourself why 99% if well and pump installers are not using this so called miracle valve? I'll tell you why. With a cycle stop valve in place any time someone cracks a faucet or runs any small amount of water which is pretty normal in most homes. Like getting a glass of water for instance. With the cycle stop valve the pump will run every time a faucet uses more than about a half a gallon of water. So where is this thing reducing cycle times? How about a full out draw on the system, say a couple of hoses running? Well, with a cycle stop valve the pump runs the entire time the hoses are running. With a standard tank system the pump also runs the entire time the hoses are running. ***********that promote this thing do so because probably 80% of well tank systems are installed using a tank that is too small for the pump which will cause problems with cycling but had the installer properly sized the tank a tank system will outperform a CSV any day of the week. Also try and find a single pump or tank manufacturer that endorses them or is offering them in their product lines.

As mentioned earlier, I edited the above post as it was overly harsh and possibly even slanderous. I kept the remainder as I felt there were some valid points.

2) On the cycle stop valve interactive demo, I believe the demo is misleading. The demo appears to be using the same size pressure tank for both examples. I understand the fact that the csv will do what it is suppose to during extended periods of water use, but most water use during the course of a day is very intermittent.
During the course of an average day’s water use, here is how I see the 2 systems comparing:

4 showers at different times.
csv cycles on and off 3 different times, running for the entire time for each shower.
properly sized tank
perhaps 5 times depending on the length of each shower .

flushing toilet
csv cycles on and off each time a toilet is flushed
properly sized tank
0, depending on fill level of tank and will only cycle once the tank's volume is used up. So for an 80 gallon tank with a 60 gallon capacity, with toilets using 1 1/2 gallons per flush, I could expect close to 30 flushes before a pump cycle occurs.

running sink
potentially, the csv may cycle on and off each time the tap is turned on if the draw is more than the capacity of the smaller pressure tank, (more or less depending on demand)
properly sized tank
0, depending on fill level of tank

dishwasher
csv cycles on then off
properly sized tank
0, depending on fill level of tank

washer
csv cycles on then off approximately 3 different times, (fill + 2 rinse cycles)
properly sized tank
probably at least once, but possibly 0, depending on fill level of tank

Now I understand the fact that I have a lot of “depending on fill level of tank” scenarios, but if your using a properly sized tank, say 82g, (which is what my local guy suggested based on my well stats), then I have approximately 50g to use before my pump kicks in to refill the tank. That 50g will flush a few toilets, do a couple of loads of laundry and dishes without having to start up, where the csv will kick in almost every time.

3) With a CSV system, if I draw a small volume from say a tap and that triggers the pressure switch to start the pump to refill the pressure tank and assuming no draw from the sink or anything else, the pump will run for the time it takes to refill the pressure tank and satisfy the high pressure cutoff. Question is - how fast will the pressure tank take to refill at this minimal refill rate? I don't know what the refilling rate is. Is it based on say 1/2 gallon per minute through a small orifice therefore it might take a minute or 2 to fill up and turn the pump off. If this is the case, the pump could actually cycle more than if using a traditional large tank during small usage draws during the day. Is this correct?

I may be missing something and would be happy if you could fill in whatever blanks are missing in my thinking.

thanks, dave
 
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Reach4

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So for an 80 gallon tank with a 60 gallon capacity, with toilets using 1 1/2 gallons per flush, I could expect close to 30 flushes before a pump cycle occurs.

A diaphragm pressure tank has a drawdown of maybe 25 to 30% of the nominal size. The Amtrol Well-X-Trol WX-251 62 gallon tank has a drawdown (capacity) rating of 16.6 if using a 40-60 PSI pressure switch and 19.2 gallons if using a 30-40 PSI switch. With the 81 gallon WX-255, the numbers are 21.7 gallons and 25. gallons.

You might put some lawn watering or other irrigation into your calculations if that would apply to you.

Otherwise, your analysis is good for your load. The big tank does take more space, but you may have plenty of space in your basement.
 
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Valveman

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Well you picked up an old thread by NHMaster, which is the same person as Tom Sawyer. He was really wrong about CSV's back then, but he is either getting closer to figuring out the many benefits or finally realized he shouldn’t argue with facts. Notice Missippian and the others on that thread really like CSV's, which is what I hear from all of my customers.

Long story short, if there were any problems caused by CSV's I would not still be in business 23 years later. None of the negative things people "predicted" about CSV's 20+ years ago ever happened. Just the opposite is true. CSV’s have made pumps last 3 to 4 times as long as normal.

I have done lots of testing on houses over the years. And I can tell you that the average number of cycles per day is almost exactly the same when comparing an old type system with an 80 gallon tank to a CSV with a 4.5 gallon tank. The more water that is used outside the home for irrigation, heat pumps, etc. the fewer cycles you get from the CSV system, even with a small tank. But even when no hoses or irrigation is being used, the number of cycles per day is the same.

You can use whatever size tank you want with the CSV. But I am telling you that anything larger than 4.5 gallons is a waste of money and space. You would have to wait 2 minutes between flushes to get the pump to cycle for every flush. But if you flush 15 times in a row, the pump just cycles once, the same as it would with a large tank. You might get a few cycles a day for toilet flushes by themselves, but usually the water is being used elsewhere in the house at the same time, and the pump is already running when you flush. Or the toilet is flushed, then hands are washed, a shower is turned on, or water is turned on somewhere else, and the CSV just keeps the pump running until everyone is finished using water. It doesn’t cause a pump to cycle on every time you crack open a faucet as some people may think.

The main reason I know the CSV is the best system, is because the big pump manufacturers have all blacklisted it as a disruptive product. The big pump companies try their best to discredit the CSV, teach their people how to talk customers out of it, tell their installers warranty will be denied, try to make a cheap VFD to compete with it, but they still can't stop me from saying the things I say because it is the truth.

I have talked to many engineers for the major pump companies who just cannot wrap their heads around this new but very simple technology. So I don’t blame you for being confused.

But with hundreds of thousands of successful installations and all of them happy customers over 23 years, anyone who makes the kind of statements you quoted above are sure making themselves look foolish.
 

superdavet

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Thanks for the input. In my initial conversation, another member pointed out the drawdown percentages. In my research, I think I reversed the numbers and thought that the 30% was the air, and the balance was the water.
 

BrianK

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Hi Dave

Your question #3 about pressure tank re-fill rate wasn't answered so I thought I'd share my thoughts (and ramble on a bit)

I looked into adding a CSV to my pump/well system a few years ago. I wanted to keep my 20 gallon pressure tank since it was relatively new rather than incur the extra expense of buying a new small pressure tank (PT) with the CSV system. I also asked how long the pump would run to refill the PT and never really got a definitive answer either. I think I was told the refill rate was about 0.5 gallons per minute so with the tank water capacity of say 6 gallons, I was under the impression that would mean the pump would run about 12 minutes - so the smaller the PT the better when using a CSV is what I determined was required to reduce this run time and 'normally' for a house what seems to be provided/recommended is a 4.5 gallon tank with about a 1.5 gallon capacity. But the low storage capacity of the small CSV PT would basically cause the pump to run almost every time I used any amount of water - something you are wondering about too. My concern was the number of starts that could occur with short run duration with every flush of the toilet or almost every time we turned on a tap - so to me, based on my usage, it appeared that the CSV with a small PT would have more starts than my current setup. If my load was more continuous - like when filling my hot tub once or twice per year , 1 start and a long run time would be great and the cycling I have now would stop. So at the time - based on this potentially long run time of 12 minutes using my existing PT which seemed excessive to me, just because I turned on a tap and the pressure tank was depleted, I decided to keep the system as it is. Yes I know that HP = Pressure * Volume so the power used to refill the tank would be quite low (high pressure & low volume) , but I didn't want the long run time compared to how long it runs now so I kept what I have which works just fine (see below)

However I noticed a more recent post which says the pressure tank refills much faster for approximately the first 3/4 of capacity (almost at full pump rate minus house demand) then at 1.0 gallon per hour for the last 1/4 of its capacity - new information for me and much different than I was led to believe before. So probably the refill time is somewhat shorter than I thought as the downstream pressure cycles between the CSV downstream pressure (pump flow rate = system demand + what ever can go into the pressure tank based on its pressure), and when the demand stops and the CSV closes, then the slow refill rate occurs due to the minimum flow rate that is built into the CSV design to provide both PT refill capability and to ensure some flow goes through the pump to avoid a no flow condition.
So the benefit of the CSV seems to be a smoother pressure delivery to the house, reduced power demand when satisfying house demand, but a slightly longer run time due to the slower refill rate of the PT (if using a larger PT) . If using the smaller PT, the pump will turn on when the small volume in the PT is used however it will run until the demand stops - no cycling during demand (great), but it will turn on with almost every new demand over 1.5 gallons (not as good as depending on small demand frequency). So you have to analyse your usage patterns.
Perhaps Valveman will chime in here.

My well pump system is 35 years old - original pump and a relatively new PT because the old one was just a tank with no bladder. I recently changed the pump just because it was so old and I didn't want if failing in the middle of winter. So it appears for my installation, the pump cycling at full flow to fill the PT isn't causing a problem so why try to fix a problem that doesn't exist with something else in the system. Maybe I'm lucky with pump longevity (?) but for me if something can go wrong it usually does. LOL.

For my usage (just normal house loads and minimal hot tub filling type demand) , rather than install a CSV with a small PT, if I could I would install a larger PT (no access to get a larger tank in place). This would reduce the number of cycles even more - an 80 gallon tank with 25 gallon usage would be great as this would reduce cycle times and extend the run time - and would be best for the pump as it would reduce the number of starts per hour and the increased run time would allow the start-up heat to dissipate. I don't really notice much pressure variability when showering. So still using the 25g drawdown of an 80g PT, I would get 10 toilet flushes, or 5 or 6 kitchen sink fills, or wash my car, or fill countless glasses of water etc etc, (all independent of each other of course), before the pump would kick in, whereas the pump would kick in almost every time each of these events occurred with a csv installed if usage was more than about 1.5 g.

You didn't mention it but I thought I'd share my thoughts on VFD's. I have some friends that like their VFD systems probably because of the soft start functionality and smoother pressure delivery (which a CSV would deliver too. VFD's add lots of complexity which you probably can't fix yourself(electronics will fail and Murphy loves to break things) and the pump affinity rules apply.
1/2 speed = 1/2 flow & 1/4 pressure = 1/8 HP. This means that with a VFD, your pump will probably never run very slowly as it would not put out enough pressure to satisfy much load so energy savings are minimally better than the CSV which operates the pump at full speed and reduced flow. The VFD controller tries to maintain pressure so you can see the speed HAS to be quite high just to satisfy the pressure setpoint. All that happens is the pump speeds up following its pump curve to supply the pressure it needs to satisfy flow. A VFD would use a bit less power than a CSV but so little difference it would not be worth the investment or complexity. Also these VFD's cause voltage spikes into the motor by the nature of how they generate a variable frequency which is really bad for the motor windings so your pump motor would probably fail faster than using line voltage with the CSV or conventional system. Then there are the lightning strikes. My 2 cents on VFDs - not worth it.
 

Reach4

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As I understand it, you can adjust the pressure at which the CSV switches from full flow to limited (1 GPM or 3 GPM depending on model). Thus if you set that pressure to be slightly lower than the pressure switch turn off pressure, the tank would fill faster after you stop using the water. If you adjusted that pressure lower, the tank would take longer to fill to the point that the pressure switch turns off. With the small tank, you would normally set the CSV to about 50 PSI in a 40-60 PSI pressure switch. Setting to 55 PSI would make a given size pressure tank fill to 60 PSI quicker.
 

BrianK

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Thanks - that makes lots of sense! At or below the setpoint of say 55 in a 40-60 system with the pump running, the tank would fill to 55 psi because the CSV is open, and once the house demand stops and the CSV closes, it just 'leaks' the last bit of pressure into the pressure tank. No one ever mentioned that before. That would allow a larger pressure tank to minimize the number of cycles, but not have it run a lot longer at low flow rate just to fill the PT. Also it would allow the pump to run when there is demand and not cycle on and off during the demand.
 

Valveman

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Hi Brian
It sounds like you have most of this figured out so I am sorry someone confused you on the tank fill time with a CSV. You can use ANY size tank you want with a CSV, and you can get ANY amount of run time you want.

For instance if you have an 80 gallon tank that holds 20 gallons of water between 40 and 60 PSI, you can make it take 2 minutes or 20 minutes to fill, depending on the setting of the CSV.

If you set the CSV to 40 PSI, the entire tank will be filled at 1 GPM, which will make for a 20 minute run time.

If you set the CSV for 59 PSI, the pressure tank will be refilled in about 2 minutes, depending on if any water is being used or not. If after the pump starts no more water is being used, a 20 GPM pump will put the first 19 gallons in the tank in about 1 minute, then the CSV will make it take 1 more minute to put the last gallon in the tank before it reaches 60 PSI and the pump is shut off.

If you are still using water for a while after the pump comes on, (shower, garden hose, hot tub) the CSV will let the tank refill to 59 PSI. Then the CSV will hold 59 PSI steady and keep the pump running for as long as you are using more than 1 GPM anywhere in the system. Only after you turn off all the faucets will the CSV top off the tank in another minute and let the pump shut off.

With the little 4.5 gallon size tank that only holds 1gallon of water, the run time is basically used as a mechanical timer. With the CSV set at 50 using a 40/60 pressure switch, the pump will always run a minimum of 30 seconds, even if the tank is emptied by a dripping faucet. When a toilet if flushed or any water is being used, the CSV will keep the pump running for as long as a faucet is on or the toilet is filling, then for another 30 seconds after all the faucets have been closed or the toilet has refilled. This 30 seconds of run time is basically timing the shut off of the pump. If before that 30 seconds is up, someone in the house opens another tap, the CSV just starts supplying that tap without the pump having ever shut off. By setting the CSV at 40 PSI with a 40/60 switch, or turning up the pressure switch to 50/70 with the CSV at 50, the run timer is lengthened to 1 minute. This will further reduce the number of cycles between small, intermittent uses of water.

Run time for the motor also doesn’t have to be nearly as long when using a CSV. The low amps caused by the CSV actually de-rates the motor load. De-rating a motor can make it safely pump hot water, so very little flow of cool well water is required to keep the motor cool. The de-rating of the motor load as well as the mechanical soft-start created by a CSV also means there is less heat to dissipate, so the usual 1 minute minimum run time and 2 minutes is better thing, no longer exists.

With the CSV and the 4.5 gallon size tank, the pump will basically come on every time you use more than 1 gallon of water. But the pump will stay on for as long as it takes to refill the toilet (no matter how many times in a row you flush it), waits for you to finish washing your hands, then gives another 30 seconds more run time before the pump is shut off. The CSV makes sure the pump stays running for as long as you are in the shower, even if the shower is on for a month.

Without a CSV the pump will start and stop every time you use 5 gallons if you have a 20 gallon size tank, or start and stop for every 20 gallons with an 80 gallon size tank. A pump can live with this type of cycling when the house just uses a few showers and things. But anytime water is used for extended periods of time like with garden hoses or filling tubs, the number of cycles can really add up.

And even though the pump can survive with some cycling, the pressure continually changing from 40 to 60 and back to 40 is usually very noticeable. You may have gotten use to it and don’t see it. But the first time you see constant pressure in the shower from a CSV, you will wonder how you ever lived with the old 40/60/40/60 thing.

Also pumps love to run. It is the cycling on and off that destroys them. So it is best to have extended run times and not let the pump cycle at all when water is used for longer periods of time. Yes the amps are reduced when using a CSV, but the longer run times can still increase the electric bill by 5 cents per day for house use. But 5 cents a day is cheap insurance to increase the longevity of your pump system. And the constant pressure showers are something you will appreciate very soon.

It is not uncommon for lightly used pumps to last 35 years. But I can assure you they don’t make pumps like they used to, so any help in making them last longer is a good idea.

And I am sorry it takes such a long, complicated explanation for such a simple little valve. :)
 

willimcrazy

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Valveman, very interesting about the csv valve. My pressure tank has gone bad so I'm going to change to the cvs1a. After being educated some on wells being drilled properly, in which ours being already installed, I'm getting sediment in which I have a large whole house filter that I change bi monthly. My question is, how much do you think it will effect the csv? The water straight from the well looks clear so it's not a heavy sediment. I've done the flushing of the well, bleach etc.. thanks
 

Valveman

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The CSV1A is designed to handle some sediment. It doesn't have any screens or holes that can plug up. If your pump doesn't build too much pressure, you can even put the filter before the CSV. Let me know which pump you have and I can tell you the pressure rating needed by the filter if you decide you want to put the CSV after the filter.
 

BrianK

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I ordered aCSV1A and can't wait to install and test it out. Hopefully it will work as well as I think it will. I have a filter upstream of my pressure tank to keep rust out of the tank and stuff. Works well with no issues and catches enough to make it worthwhile. I'll take some amp readings before and after the CSV is in.

Llgetfa - I guess I didn't read your posts as thoroughly as I should have. Sometimes it takes a bigger bat to pound key points in. The lightbulb moment for me was understanding the adjustable feature of the CSV and that made it all come together - basically it's an adjustable leaky pressure regulator - simple. And the ability to use a larger PT answers all the questions of the small usage concerns.
 
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