Pressure tank

Discussion in 'Pumps and Tanks Well Forum & Blog' started by Beany, Dec 29, 2011.

  1. Beany

    Beany New Member

    Messages:
    3
    Location:
    Green Valley Il.
    How often should pump cycle? I have a 63 ft well,44 gal. pressure tank,pressure switch at 45/65,air in tank set at 43 lbs. How often should pump cycle with faucet open?
  2. LLigetfa

    LLigetfa DIYer, not in the trades

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  3. Beany

    Beany New Member

    Messages:
    3
    Location:
    Green Valley Il.
    Thanks,still learning this site, not sure that my first question got answered
  4. LLigetfa

    LLigetfa DIYer, not in the trades

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    Location:
    NW Ontario, Canada
    Unless we know how many GPM the pump produces and how many GPM you draw, we are just guessing. Your tank should give you about 10 gallons of drawdown so a 10 GPM pump would run for about 1 minute with no draw. The drawdown should allow a 2.5 GPM showerhead to flow for 4 minutes before the pump starts back up.

    Does that answer your question?
  5. valveman

    valveman Moderator Staff Member

    Messages:
    4,380
    Location:
    Lubbock, Texas
    That size tank should hold about 12 gallons of water, and a normal faucet puts out about 3 GPM. So I am guessing the pump will run for about 1 minute, and be off for about 4 minutes while the faucet is running. But to answer your question, the pump should NEVER cycle while you are running a faucet or anything long term. You either need to always run 4 faucets at a time, or use something like a Cycle Stop Valve to keep your pump from cycling when using small amounts of water. On for a minute and off for 4 minutes doesn't sound too bad if you say it quickly. But that can turn into almost 300 cycles every 24 hours, which will cause you to need a new pump very soon.
  6. Tom Sawyer

    Tom Sawyer In the Trades

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    Location:
    Maine
    But with a CSV when you open a single faucet for say a glass of water, the pump comes on within seconds and runs until you shut the faucet off ( a few seconds after actually ) According to Goulds a properly sized expansion tank and pump will cycle far less often than the same set up using a CSV. Of course, they sell pumps and tanks and not CSV's but my own lab tests have shown the same thing. The single biggest problem with pump cycling is caused by oversized pumps and undersized expansion tanks. I have found that most well driller/installers are pretty happy selling what they call the contractor package which generally consists of a submersible matched to the well's recovery and static and regardless of well yield and pump the same Xtrol 202 tank gets installed for everybody. Now an Xtrol 202 is a pretty good tank and usually not a bad choice as we are getting an average of 15 years out of a submersible around here but, regardless of pump size, upgrading to a larger tank will greatly reduce all cycle times including that "glass of water" draw. CSV or not, under a full, long term draw the pump should run continuously.
  7. LLigetfa

    LLigetfa DIYer, not in the trades

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    Huh? What are you basing that on? The OP has 10 to 12 gallons of drawdown for his 44 gal tank so then how would one glass of water do that? Adding a CSV won't change the drawdown.
  8. Tom Sawyer

    Tom Sawyer In the Trades

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    3,063
    Location:
    Maine
    Usually a CSV is installed with a much smaller tank. Using his same tank, what will a CSV change?
  9. LLigetfa

    LLigetfa DIYer, not in the trades

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    3,828
    Location:
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    Is this a trick question? Depending on water use, given the parameters in this thread, it could stop the pump from cycling hundreds of times a day.
  10. Tom Sawyer

    Tom Sawyer In the Trades

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    3,063
    Location:
    Maine
    How? Really? Hundreds of times a day? Think about the logical operation of the pump and the pressure tank.

    So I have a tank with a 10 gallon draw down before the pressure switch cuts in which means that a couple toilets can flush and quite a few glasses of water will draw before the pump starts. On a longer demand the tank will draw down the 10 gallons and then the pump will run. If the draw is heavy the pump will run continuously until the draw stops and then the tank will recover and the pump will shut off. With a CSV that tank filling will take slightly longer due to the restriction in the CSV so yes, longer run time there. I have exhaustively tested both set ups and in actual "residential" use it turns out that a properly sized expansion tank actually cycles the pump less often than a CSV with a small tank which is how they are usually installed. When I lived in Florida we did a ton of sprinkler systems and in that case a CSV does indeed to an admirable job of preventing cycling because the pump runs constantly when the sprinklers are on. For residential use though I think it's overkill and unnecessary provided the pump and tank are properly sized. But that's just my opinion based on a lot of testing and experience.
  11. valveman

    valveman Moderator Staff Member

    Messages:
    4,380
    Location:
    Lubbock, Texas
    Using a pressure tank with 10 gallons of draw and running a 3 GPM faucet, a 10 GPM pump will run one minute and be off three minutes, which is a cycle every 4 minutes. That is 15 cycles per hour or 360 cycles per day. No matter the size of tank you use, a CSV would make the same system only cycle once instead of 360 times in the same period, saving hundreds of cycles per day.

    For in the home use only, a larger tank will of course let you flush more toilets and get more glasses of water before the pump starts. But how many times a day do your really flush a toilet or get a glass of water? Even if the pump has to start every time you flush and every time you get a glass of water, it doesn’t add up to very many cycles.

    Destructive cycling comes from times when you “open a faucet” for extended periods of time as for long showers, filling a pool, or running a sprinkler. That is when a CSV, no matter the size of tank, can save hundreds of cycles per day. For having the CSV option to save hundreds of cycles per day for extended water uses, even with a small tank, an extra 20 cycles per day for just flushing and glasses of water is a moot point.

    However, if you are really trying to do the absolute best job for your customer under every possible circumstance, use the CSV with the larger tank. Now you are able to flush several times and get many glasses of water before the pump starts. But when you “open a faucet” for extended water uses, the CSV takes over and eliminates hundreds of cycles per day. You would have the best of both worlds, so to speak.

    Even for systems with no out of the home water uses, the CSV and small tank has many advantages. The smaller tank cost less, takes up less space, and requires less of the homes heating energy. The smaller tank lets you have the constant pressure from the CSV much sooner. With a larger tank, you will feel the shower pressure decrease every second until the pump starts. Then you only have good constant pressure for the last half of your shower. With the CSV and a small tank, you will feel the good constant pressure before you get the temperature adjusted in the shower, and it will stay strong and constant until you turn off the shower, no matter how long that is. An extra 20 cycles per day for toilet flushes is a small price to pay for the luxury of instant constant pressure using a small tank with the CSV.

    However, my own tests, which I have been doing for about 20 years, shows that the small tank doesn’t increase the number of cycles (for home use only) by more than about 5 times per day. This is because when a toilet is flushed, the pump is usually already running for a shower, washing a toothbrush, or something else, and flushing the toilet doesn’t add another pump cycle.

    I am always amazed at how many pump installers try desperately to find a single negative thing about the CSV, instead of adding up all the positives. Either they don’t want their customers to have the benefits of constant pressure, reduced costs, longer pump life, and a smaller footprint, or they wouldn’t know a good thing if it hit them in the face.
  12. LLigetfa

    LLigetfa DIYer, not in the trades

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    Location:
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    I would like a few examples of such a draw on a residential system. Now, the pump GPM is unknown so we have been using 10 GPM in our calculations. With the exception of my wife's soaker tub, I don't have any other single point of use that could draw as fast as my pump produces. Even outside, the soaker hoses and sprinklers cause cycling. I watch the pressure rise and fall on my sprinklers for hours on end. If it were not for the micronizer on my iron filter, I would be using a CSV.

    I don't sell CSVs and I don't have a vested interest in promoting them. I advocate the CSV because the evidence shows they work and they are a marvel of engineering simplicity.

    You appear to have a bias against CSV and are trying to use FUD to support it. I see it as a recurring trend in many of your posts. Why else would you make claims that a glass of water drawn from a 44 gallon tank will cause a pump to cycle and that the pump would run continuously under heavy draw, both of which are outside normal parameters?
  13. Tom Sawyer

    Tom Sawyer In the Trades

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    3,063
    Location:
    Maine
    Re-read my post. I did not say that at all. What you should understand is that unlike most folks I do not have to take everything I read at face value. I have the luxury of having both the time and the facilities to actually test these things under normal operating conditions. You do me a disservice to imply that I have a vendetta against CSV's when I do not. In fact, when I lived in Florida my company installed a great many of them for sprinkler and irrigation systems where the pump curve and the demand made their use warranted. However, I have a problem with slapping a CSV anywhere and everywhere when in fact a properly sized pump and expansion tank will outperform a CSV every time. The fault here lies with installers that have been hell bent on installing the "contractor" well package that in their mind is a one size fits all solution rather than calculating the well production rate/ pump size / delivery pipe length and size / and last but not least, the piping and distribution system within the house as well as the estimated normal usage.
  14. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
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    Location:
    Maine
    There are positive and negative things associated with any product. The CSV certainly has it's applications, however I hate to see it used as a band aid solution for pumps and tanks that are undersized and because most driller/installers are only interested in selling a couple of products to keep their inventory down.
  15. valveman

    valveman Moderator Staff Member

    Messages:
    4,380
    Location:
    Lubbock, Texas
    “Properly sizing a pump and pressure tank” is the flaw in you theory. You are implying that you know HOW the homeowner will use the water. A homeowner who later decides he/she wants a heat pump, tractor sprinkler, or a soaker hose just shot your theory full of holes.

    You can always HOPE for the best, or you can prepare for the worst-case scenario (use a CSV) and be covered no matter what happens.

    And if you think anything can “outperform” a CSV, then you really don’t understand what you are testing for.
  16. valveman

    valveman Moderator Staff Member

    Messages:
    4,380
    Location:
    Lubbock, Texas
    "Properly sized piping as well as pump and tank sizing will greatly reduce or eliminate that pressure loss feeling but even so with a pressure balanced tub/shower valve you are not going to feel a pressure difference in the shower."

    So now you are using the "pressure balanced tub/shower valve" as the bandaid because you don't have a pump system that delivers constant pressure to start with.
  17. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,828
    Location:
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    Ah, but therein lies the art of FUD. Leave a negative impression in the first sentence and then CYA in the fine print lest someone calls you on it.

    You still did not answer my question.
  18. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,063
    Location:
    Maine
    Here's what I can tell you. Here in the northeast most of our wells run between 100 and 400 feet with an 8" steel case. I would say from experience that the average well driller/installer is going to drop a 1/2 / 7 or a 3/4 / 10 down the hole and use an Xtrol 202 regardless of the pump or the demand. Still, I would bet that the average pump lasts a good 15 years and many well over 20. My own pump has been down the hole for 35 years now. Now, maybe a lot of that has to do with cooler water temperatures and larger well case which keeps the pumps cooler but if cycling is a killer than we should all be replacing way more burnt out pumps than we do.

    LLigetfa - Again, re-read my post. Take the time, read carefully......breath, relax
    Here is what I posted. I can't find a question in your post.

    So I have a tank with a 10 gallon draw down before the pressure switch cuts in which means that a couple toilets can flush and quite a few glasses of water will draw before the pump starts. On a longer demand the tank will draw down the 10 gallons and then the pump will run. If the draw is heavy the pump will run continuously until the draw stops and then the tank will recover and the pump will shut off. With a CSV that tank filling will take slightly longer due to the restriction in the CSV so yes, longer run time there. I have exhaustively tested both set ups and in actual "residential" use it turns out that a properly sized expansion tank actually cycles the pump less often than a CSV with a small tank which is how they are usually installed. When I lived in Florida we did a ton of sprinkler systems and in that case a CSV does indeed to an admirable job of preventing cycling because the pump runs constantly when the sprinklers are on. For residential use though I think it's overkill and unnecessary provided the pump and tank are properly sized. But that's just my opinion based on a lot of testing and experience.
    Last edited: Jan 1, 2012
  19. Texas Wellman

    Texas Wellman In the Trades

    Messages:
    522
    Location:
    SE Texas-Coastal
    FWIW-I'm seeing an average of 12-15 years of service for submersible pumps here, and not unusual at all to see one last for 20+ years. My dads own pump, a 1.5 HP mounted to a way too small under sized galv. 82 gallon tank, lasted for 28 years. It was a Sta-Rite VIP with a cast-iron head.
  20. DonL

    DonL Jack of all trades

    Messages:
    3,812
    Location:
    Houston, TX
    So if You have a CSV, It should last for 100 Years ?

    I need one of them. I must be getting old, I do not understand the problem with Old School.


    Have a Great New Year Texas Wellman, and All.
    Last edited: Jan 1, 2012
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