Pressure Tank and CSV

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Dogwell

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Nolan has it right that narrowing the pressure switch bandwidth would make a large tank act like a small one. That would just be wasting the extra money spent on the large tank. Plus a pressure switch that can do 10 PSI between on and off will cost more as well.

Wondering has a good idea to try the 4.5 gallon tank so you can see it in action, which will make it easier to understand. Then if you decide you want a larger tank you can just add a 20 gallon size tank anywhere after the CSV. You can even plumb the 20 gallon tank to a faucet and open the faucet. Since the 4.5 gallon tank is on the CSV and close to the pressure switch, an additional tank can be added anywhere in the plumbing past the CSV. Then you would have 24.5 gallons of tank size that would deliver about 6 gallons of drawdown.

It has always been said that a "properly sized tank" that will make the pump run for one minute and be off for one minute will reduce the pump cycles enough to make the pump last a long time. The only time this doesn't work is when using the pump for irrigation or something long term and using less than the maximum output of the pump. This would cause the pump to be destroyed from cycling on and off repeatedly for hours.

With a CSV you don't have to worry about running water at less than max pump output for long periods of time. The CSV will not let the pump cycle when using more than 1 GPM no matter what size tank you have. Add to that the fact that the CSV and 4.5 gallon size tank will cycle the pump the same number of times per day for house use only as a "properly sized pressure tank" without a CSV. Then it stands to reason that the CSV with the 4.5 gallon size tank will make the pump last just as long as the non CSV system with a larger tank as long as it has perfectly matched irrigation zones that don't cause cycling.

A lot of people will tell you that most pumps will last 20-30 years with a "properly sized pressure tank" and perfectly matched irrigation system. In the 25 years we have been using Cycle Stop Valves with small tanks, we have found they will last the same 20-30 years as the old style systems, and it doesn't even matter if the sprinkler system is sized to match the pump. It does stand to reason that the CSV with a large tank can reduce the cycles for house use even more. But I don't think it will make the pump systems last any longer than 20-30 years, as something besides cycling will probably cause the system to fail in that length of time. Even if the pump last more than 30 years, a wire will break, a pin hole will develop in a pipe, a check valve will fail, or something else will cause the system to stop making water. Plus I am now 57, if it last that long some one else will have to worry about it. :)

HI Cary,

Will you please answer my previous comment:


I don't understand the house equivalency usage here. Can you please explain? How does tank size relate to the number of houses? Would you say that a fair estimate of flushing a new toilet and washing hands leads is a 2.5 gallon draw? So in the ideal scenario starting with a full capacity 20 gallon tank, the pump would allow two toilet uses before starting. In a more realistic scenario with some water already being used up, the pump would start at every use, in which case there's no point in increasing to 20 gallons from 4.5 gallons. Is that right?

I want to get a CSV and need to replace my tank. I just need to figure out which size tank to get to avoid the pump starting at every flush and still take advantage of the constant pressure.

Can you please tell me if I were to get a separate tank, which parts I'd need and what the cost would be for the CSV?
 

Valveman

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I consider an average house to have 2 restrooms and 5-6 people using approximately 300 gallons per day. If you have 4-5 restrooms and less than 10-12 people running at 50/70 pressure the PK1A with a 10 gallon tank is all you need. That is what I have with a 25 GPM, 2HP pump. I have had as many as nine people in two houses with varied irrigation and a pool on this system. Even then the main reason I use the 10 gallon tank is because I use 50/70 pressure, and the pressure tank holds less at 50/70 than it does at 40/60. My CSV is at the well because I have many taps on the line before it comes into the house where the pressure tank and pressure switch are. But if I could get the pressure tank and pressure switch before any water lines that tee off, I would have just screwed the 10 gallon tank into a CSV1A, which makes for a very easy installation.
10 gal tank sized.jpg
 

Dogwell

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I consider an average house to have 2 restrooms and 5-6 people using approximately 300 gallons per day. If you have 4-5 restrooms and less than 10-12 people running at 50/70 pressure the PK1A with a 10 gallon tank is all you need. That is what I have with a 25 GPM, 2HP pump. I have had as many as nine people in two houses with varied irrigation and a pool on this system. Even then the main reason I use the 10 gallon tank is because I use 50/70 pressure, and the pressure tank holds less at 50/70 than it does at 40/60. My CSV is at the well because I have many taps on the line before it comes into the house where the pressure tank and pressure switch are. But if I could get the pressure tank and pressure switch before any water lines that tee off, I would have just screwed the 10 gallon tank into a CSV1A, which makes for a very easy installation.
View attachment 42086

Thanks, Cary, but my question is specifically regarding a house where water usage is intermittent. No irrigation, no pool and taps / toilets on and off throughout the day rather than simultaneous usage. In this scenario, apart from the extra cycling during showers, the main benefit of a CSV is the constant pressure. The drawback of a CSV with a small tank as opposed to CSV with a mid sized tank would be increased cycles. Is there anything wrong with what I've said so far?

If not, then can you please clear up my confusion re a 20 gallon tank? My question earlier was would you say that a fair estimate of flushing a new toilet and washing hands leads is a 2.5 gallon draw? So in the ideal scenario starting with a full capacity 20 gallon tank, the pump would allow two toilet uses before starting (assuming no water being used elsewhere). In a more realistic scenario with some water already being used up, the pump would start at every use, in which case there's no point in increasing to 20 gallons from 4.5 gallons. Is that right?
 

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To confuse you even more, draw down has much less to do with it than run time. With the 4.5 gallon size tank you can set the pressure switch and CSV to make the fill time of the tank to be from 30 seconds to 1 minute. With the 10 gallon tank you can make the run time up to 2 minutes. The pump will run for 2 minutes to fill the tank after you have turned off the last faucet. The purpose of letting the pump run for 2 minutes after you stop using water, is to give someone else in the house a chance to start using water before the pump cycles off, which will just keep the pump running. If the pump runs for 2 minutes and shuts off after you stop using water, there is a pretty good chance that it will be some time before someone else in the house uses any water, so the pump could be off for quite a while.

Now if someone is standing there with a stop watch and turns on the kitchen sink exactly 2 minutes and 5 seconds after you stopped using water, the 2 gallons in the 10 gallon tank will still need to be used before the pump will come back on. So a 1 GPM kitchen faucet would need to be open for 2 minutes, and the pump would stay off for 2 minutes, before the pressure dropped from 70 to 50 and the pump is started again.

The reason we use a 20 gallon tank on up to 10 houses, is because we can set it up to get about 3 minutes of run time to fill the tank, not because it has 5 gallons of draw down. Even with multiple houses or just multiple people in one large house, during certain times of the day there will rarely be more than 2-3 minutes between water uses, so the pump just stays running for those periods of time. When water stops being used every 2-3 minutes, it will usually stay off for some period of time, so the pump stays off for that time as well.

What good is 5 or even 25 gallons of tank draw down when you have a large house or multiple houses that use hundreds of gallons per day? Your water comes from the well, as you have millions of gallons available to be pumped as needed. All a pressure tank has ever been for is to reduce the number of pump cycles while THE PUMP was delivering as much water to the house(s) as needed.

With a Cycle Stop Valve you are filling the tank at 1 GPM instead of 10-25 GPM, so the tank can be much smaller and still give the run time required. With a CSV the pump will not shut off WHILE you are using water. So all you really need is enough run time that when multiple people are using water, the pump stays on between uses long enough to see if someone else needs water before the pump shuts off. When everyone is finished using water, the pump will stay off until someone else uses water, no matter if the tank has 1 gallon of 25 gallons of draw down.

Draw down was very important with the old pressure tank only systems because the pump would continue to cycle on and off WHILE you were using water. Draw down is not so important with a CSV because the pump will never shut off until you are finished using water.

The PK1A with the 4.5 gallon tank will handle the average house just fine. But if you think you have a lot of intermittent uses of water, opting for the 10 gallon size tank will give you the run time to make it handle any situation.
 

Dogwell

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The benefit of extending the run time to 2 or 3 minutes exists on the premise that there is going to be frequent water usage during a short period of time. It makes sense to run the pump a little bit longer if someone is going to use water again in a few minutes. I understand this completely. But let's imagine the opposite scenario. Someone uses the water. It's not used again until ten minutes later. Then again after 5 minutes. Then again after 15. If these occurrences are not of long duration and do not overlap with the extended run time of the pump, the CSV with small tank will lead to increased cycles. Let's talk about this scenario.
 

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As long as the pump is off for at least one minute before restarting you won't have a problem. And like you say it will probably be more like 5 or 15 minutes before someone uses water again, so the motor has had plenty of time to cool down and starting the pump again is certainly not a problem. Cycling the pump on each time you need water is much better for the pump than having it cycle on 1 minute and off 1 minute over and over while water is being used.

Even though the small tank with a CSV will cause the pump to cycle on with each use of water, it won't let the pump cycle on and off repeatedly while you are using water. So the overall number of cycles with the CSV and small tank will be virtually the same as a non CSV system with a so called properly sized tank. Using a tank that is just slightly larger like the 10 gallon size will greatly reduce the number of cycles compared to the old pressure tank only systems.

You don't need a big tank to supply water during times when the pump is off, as long as you have a CSV to keep the pump from cycling during times when the pump is on.

Look at all the VFD and "tankless" control systems the pump companies are pushing. These kinds of controls will turn the pump on as soon as you crack the faucet, and will turn the pump off a couple seconds after water stops being used. There is no run time or off time with these type systems, which is very bad for the pump/motor.

But with the CSV and a 4.5 gallon tank there is never a short run time or off time. And using the 10 gallon tank instead increases the run time and the off time even more. But 25 years ago I would have been telling you to install the largest tank you can get through the door, so I certainly understand why people have such a problem understanding this new and better concept.

I still use 86 gallon size pressure tanks on some systems. I use a single 86 gallon size tank to replace a water tower and feed a system with 100,000+ people. And again, you can use any size tank you want with a CSV. But storing water for times when the pump is off is not nearly as important as preventing the pump from cycling during times when water is being used and the pump is on.
 

SuperGreg

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I guess I'm also wondering the same thing as Dogwell. Just going by my own usage, my pump runs (maybe) once when I take a shower depending on the starting pressure in the tank. We can go most of the day using water occasionally (toilets, washing hands, rinsing dishes, etc) without the pump cycling. I understand the CSV with a small tank results in a much more constant water pressure as you describe it, but I can't help but think that it results in more pump cycling, not less, except in the scenario that water is being constantly used.

Now that I think about it, the back flushing of the filters at night would be the highest usage of continuous water. Those take quite a few cycles.
 

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The more water you use, the more beneficial a CSV is. If you only use 50 gallons per day, one gallon at a time, the CSV and small tank would make the pump cycle about 25 times. If you had a couple of really big 80 gallon tanks, the pump would only cycle once per day. Neither of these ways will hurt the pump. The CSV uses a little inexpensive tank that doesn't take up much room, and delivers strong constant pressure for each use over 1 gallon. The two big tanks would be expensive, take up a lot of room, and would deliver water at steadily decreasing pressure. Plus I had rather have my water come fresh and straight from the well, than have it sitting in a rubber bag for hours before I need it. But I guess that wouldn't make a lot of difference if you have to treat the water anyway.

Any time you run a garden hose, or use water for any length of time, the CSV completely eliminates cycles no matter the size of the pressure tank. And even houses without any long term water use can have something like a toilet flapper leaking, which can cause lots of cycles before you figure out what is happening. Using a Cycle Stop Valve makes a pump system able to handle any flow rate you want to use for any length of time. With a small tank the CSV system will cycle slightly more for intermittent uses like just house use, but you still cannot make the pump cycle enough to hurt anything.
 

LLigetfa

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The more water you use...
...depending on how fast you use it. If you draw it fast enough that the pump cannot reach shutoff, then it will not cycle. That then also depends on what pressure the cut-off is set to and what pressure the pump will deadhead at.
 

dcg4403

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Old thread but wanted to give my single experience. Great discussion BTW.

So our submerged well pump failed so I only have 300 gal holding tank which I have been refilling via a 200 tank in my truck. Needless to say, I have been watching our water and pump cycles closely. We have a traditional non-CSV system with a 2hp pump + 62 gal pressure tank.

To save water (forces compliance w the kids), I have been shutting off our booster pump. I also have to do this when our 300 gal holding tank is near empty.

I understand what Cary is stating about the benefits of a CSV but I do not find them true in my real-life situation.

So we are able to take 2 quick showers (30-45 sec shower sessions), wash our hands quickly (6-10 times turning off water while scrubbing), and flush the toilets 2-3 times BEFORE the pressure suffers greatly. A CSV system would have wanted to cycle a roughly a dozen times (~10-15 times). While my non-csv booster pump setup would have only cycled once, maybe twice AT MOST.

If we think about this annually, that is a LOT more pump usage with a CVS + small tank setup. For the last few years, I know that my booster pump only cycles 5-7 times during the day for my house of 5 people under our normal use (we do try to conserve of water usage by turning off faucets quickly & not taking efficient showers). Does it cycle more occasionally? Yes. Would it cycle as much as a CSV? HECK no.

So I very confidently conclude a CSV would actually make my daily cycles FAR greater than my existing system. And I presume resulting in shorter pump life. Hard to argue against this as this is my current real life situation. Not theoretical examples that don't appear to translate to my situation. Also, no one in my family has ever complained about a loss of pressure at ANY single occurrence in the last 6 years. So for me this debunks some of what Cary is suggesting.

Everyone has a different use case. Some of us become blinded by biases. I can certainly see the benefits of CSV in many use cases. However, I also see & have experienced the benefits of non-CSV in many use cases, too. I fault Cary for being overly biased. I applaud Cary for his immense knowledge, information sharing, and overall helpfulness. As an R&D engineer, I have learned a lot from reading this thread.

Does the added cost outweigh the benefits? For some, absolutely Yes.

For me, No, not one bit. Let me elaborate by saying installing a CVS to my existing system would be a complete waste of money. And given the great working nature of my existing system, replacing my 62 gal tank last year was the right choice. My booster pump is now 25 years old and pumping strong still! I think providing real data about CSV vs non-CSV correlated to pump life would be great to see and help settle some debate.
 
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Valveman

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Old thread but wanted to give my single experience. Great discussion BTW.

So our submerged well pump failed so I only have 300 gal holding tank which I have been refilling via a 200 tank in my truck. Needless to say, I have been watching our water and pump cycles closely. We have a traditional non-CSV system with a 2hp pump + 62 gal pressure tank.

To save water (forces compliance w the kids), I have been shutting off our booster pump. I also have to do this when our 300 gal holding tank is near empty.

I understand what Cary is stating about the benefits of a CSV but I do not find them true in my real-life situation.

So we are able to take 2 quick showers (30-45 sec shower sessions), wash our hands quickly (6-10 times turning off water while scrubbing), and flush the toilets 2-3 times BEFORE the pressure suffers greatly. A CSV system would have wanted to cycle a roughly a dozen times (~10-15 times). While my non-csv booster pump setup would have only cycled once, maybe twice AT MOST.

If we think about this annually, that is a LOT more pump usage with a CVS + small tank setup. For the last few years, I know that my booster pump only cycles 5-7 times during the day for my house of 5 people under our normal use (we do try to conserve of water usage by turning off faucets quickly & not taking efficient showers). Does it cycle more occasionally? Yes. Would it cycle as much as a CSV? HECK no.

So I very confidently conclude a CSV would actually make my daily cycles FAR greater than my existing system. And I presume resulting in shorter pump life. Hard to argue against this as this is my current real life situation. Not theoretical examples that don't appear to translate to my situation. Also, no one in my family has ever complained about a loss of pressure at ANY single occurrence in the last 6 years. So for me this debunks some of what Cary is suggesting.

Everyone has a different use case. Some of us become blinded by biases. I can certainly see the benefits of CSV in many use cases. However, I also see & have experienced the benefits of non-CSV in many use cases, too. I fault Cary for being overly biased. I applaud Cary for his immense knowledge, information sharing, and overall helpfulness. As an R&D engineer, I have learned a lot from reading this thread.

Does the added cost outweigh the benefits? For some, absolutely Yes.

For me, No, not one bit. Let me elaborate by saying installing a CVS to my existing system would be a complete waste of money. And given the great working nature of my existing system, replacing my 62 gal tank last year was the right choice. My booster pump is now 25 years old and pumping strong still! I think providing real data about CSV vs non-CSV correlated to pump life would be great to see and help settle some debate.

Lol! Of course a CSV is not going to help much if you don't let the kids run the faucet long enough to get their toothbrush clean. It certainly won't help when you turn off the pump. Your "real life situation" is completely different than most people. Most people don't like having to run around in the shower to get wet. As a matter of fact I can count on one hand the number of people I have talked to in 50 years who ration water the way you do. I can understand though. If you are hauling water in a 200 gallon tank, you don't have an extra gallon to waste. I know another guy why has a yard full of cactus, and gets by on 2 quarts of water a day. Even so, the CSV will work fine with your 62 gallon (12 gallon draw) tank. You could still ration water the way you are now. However, the CSV wouldn't do much unless you used more than the 12 gallons the tank holds at any given time. The CSV would still give the pump a mechanical soft stop, which would save the check valve and other things. Plus, the CSV would be there and ready to keep the pump from cycling anytime you use more than 12 gallons.

There is a lot of data on CSV verses Non-CSV use. But that is on normal houses that use water normally. I applaud you on your conservation of water, but very few people would be happy living that way. Most people like a good long hot shower or maybe just enough water to get their toothbrush washed off. My wife would KILL ME if I turned the pump off!
 

LLigetfa

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A 45 second shower ....... impressive.
Makes a "Navy Shower" seem like a luxury.
While I am not so frugal with water, if starting from full, I can take a shower without the pump coming on.

Here is a 24 hour snapshot of water use where my pump cycled 11 times. Obviously when irrigating gardens, it could be completely different depending on GPM of draw. My refill rate is limited by my micronizer so one must subtract the draw so only the net difference goes to refill.
chrome_2021-03-06_08-51-32.jpg


The use case that @dcg4403 outlined is a bit of apples to oranges since it is all about the size of the tank regardless of whether there is a CSV or not.
 
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