Irrigation system on a well pump

Discussion in 'Irrigation / Sprinkler Forum' started by mihomeowner, Sep 8, 2013.

  1. mihomeowner

    mihomeowner New Member

    Messages:
    40
    Location:
    Michigan
    I am on a well. I have a 12 zone sprinkler system around my house. When these are installed, are they set up so the flow rate is calculated to be exactly what the well puts out, so the well isn't cycling on and off?

    I've done some research, and I've read a couple things where people have said that your well pump should run continuously while your sprinklers are on. This make sense to me, because the well starting/stopping a bunch has got to be bad for it.

    Some zones, it runs perfectly, and the well pump and zone work in unison so that the pump isn't cycling on and off.

    However, I have a few zones where the pump will run for a minute, then shut off, then the system will lose pressure and cycle the pump back on. I can hear my pump clicking on and off about every 2 minutes. I know this can't be good for it (and it causes some water hammer as well). My system is set at 30psi low end and 50psi on the high end.

    My basic question is - am I correct in assuming it should run continuously? There must be something up with the zones in question that are making it cycle. Perhaps they aren't putting out enough water?

    Thanks for any tips.
  2. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,826
    Location:
    NW Ontario, Canada
    Yes, the pump should run continuous. You could try upping the settings to 40/60 to see if that moves it off the curve enough.

    That said, if on that zone the pump runs for only a minute, then you have the tank sized all wrong. It should run for a minute with no water use. While using water, it should extend the runtime.

    Rather than upsize the tank, consider a CSV.
  3. mihomeowner

    mihomeowner New Member

    Messages:
    40
    Location:
    Michigan
    Thanks for your reply and your help. I'm a little confused though. Your saying I have the wrong size tank (I assume your talking about the bladder?)

    If the zone isn't set up property, wouldn't that mean the well pump kicks on for a minute and then shut off, as opposed to running continuously like it should? I'm not sure I understand what you mean by "you have the tank sized all wrong"
  4. Wet_Boots

    Wet_Boots Sprinkler Guy

    Messages:
    798
    Location:
    Metro NYC
    One can also change rotor nozzles to increase flow and reduce cycling.
  5. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,826
    Location:
    NW Ontario, Canada
    The tank should be sized for the pump to run at least one minute, worst case. The worst case would be when there is next to no water use. If it only runs for a minute with the zone running, then it must run much shorter when you are perhaps brushing your teeth.
  6. valveman

    valveman Moderator Staff Member

    Messages:
    4,370
    Location:
    Lubbock, Texas
    A good irrigator can usually size the zones to match the pump. But that doesn’t mean the zones match the yard. Most irrigation systems have areas that need small GPM zones. Overlapping these areas with other zones doesn’t always work. Also if you ever use a garden hose, it throws the irrigation design out the window. Small zones and garden hoses will cause the pump to cycle itself to death. A bigger tank just slows down the cycling. Not properly sizing the tank, means not getting the biggest tank you can find.

    Some irrigators see the CSV as a Band Aid for a bad irrigation design. Others use the CSV as a way to design the perfect irrigation system. The CSV will work with even a very small pressure tank, and allows you to use any size zone down to 1 GPM, or a garden hose, without cycling the pump. In this way the irrigation system can be sized to match the yard, not the pump. The CSV can be a water saving feature, as doubling up the zones, can over water certain areas and waste a lot of water.

    For irrigation only, if every zone could be made to match the pump, a pressure tank would not be needed. You could just run the pump with a timer and relay. But as you have noticed, it is almost impossible to match every zone to the pump. Even when you do, a slight change in the water level in the well, or slight wear in the nozzles or pump, can change everything. A zone that puts out slightly too much water will cause low pressure. A zone that puts out slightly too little water will cause cycling.

    Then if the pump also supplies the house, a large enough irrigation zone to keep the pump from cycling also means there is not enough water left for the house to use. So the irrigation MUST be done at off hours, when you don’t need water for the house. Even then, who is to say that you would not need a shower at 3AM during an illness or just a restless night, and the sprinklers are using all the water.

    With a CSV you can size the zones anyway you want, and even save back a little water for house use. With the CSV you can run the sprinklers or hoses anytime you want, still have water for the house, use a very small tank without cycling the pump to death, and even conserve water.
  7. Wet_Boots

    Wet_Boots Sprinkler Guy

    Messages:
    798
    Location:
    Metro NYC
    The cheapest remedy is tweaking the pressure switch settings. Just know that you want to increase the pressure tank air charge if you go much beyond adding 10 psi to the switch settings.
  8. valveman

    valveman Moderator Staff Member

    Messages:
    4,370
    Location:
    Lubbock, Texas
    Tweaking the pressure switch of a jet pump might work, but a submersible may have to operate at 100/120 to prevent cycling, which is not practical. On either kind of pump, tweaking the pressure switch is not safe, as setting it a little too high may cause the pump to melt down if it can’t reach shut off pressure.

    A CSV is not a sign of an irrigator who doesn’t know how to do the calculations correctly. A CSV is a sign of irrigator who knows how to design a system to match the yard or field, instead of matching the pump.
  9. mihomeowner

    mihomeowner New Member

    Messages:
    40
    Location:
    Michigan
    Thanks, a lot of good info in that post.
  10. mihomeowner

    mihomeowner New Member

    Messages:
    40
    Location:
    Michigan
    Thanks for the reply. From what I understand, moving from a 30psi-50psi to 40psi-60psi isn't really that big of a deal, if done right. Is that correct?
  11. mihomeowner

    mihomeowner New Member

    Messages:
    40
    Location:
    Michigan
    Couldn't I try this and then monitor the pump for a few days to make sure it can reach the shut off pressure? Also the house is 10 years old and we aren't the original owner but maybe if I found out what type of well pump it is, I could see if it is safe to run it at 40-60.

    I will look in to the CSV, I took a quick look at your website. How hard are they to install?
  12. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,826
    Location:
    NW Ontario, Canada
    Valveman was suggesting that a sub may need to be set as high as 100-120 PSI to move it off the curve enough and in so doing, risk deadheading. At 60 or 70 PSI, it is not very likely to deadhead.
  13. valveman

    valveman Moderator Staff Member

    Messages:
    4,370
    Location:
    Lubbock, Texas
    If you give me a pump model number and depth to water in the well, I can tell you how high you need to adjust the pressure switch to keep it from cycling.
  14. Wet_Boots

    Wet_Boots Sprinkler Guy

    Messages:
    798
    Location:
    Metro NYC
    If you have a Square-D pressure switch, the instructions might be on the cover. Since you say the cycling is about two minutes between starts, you probably aren't so far from steady operation.

    On a sprinkler system of rotor heads, an installer wouldn't spend too much effort tweaking a pressure switch beyond making 30/50 into 40/60 - the installer has different sized sprinkler nozzles to exchange with the installed ones, in order to get a flow match with the pump.
  15. mihomeowner

    mihomeowner New Member

    Messages:
    40
    Location:
    Michigan
    I was able to dig up the well records from my county record department, but it's not very legible. I couldn't find any info on my well pump using the model numbers they gave me. Maybe it makes more sense to you guys that know the business.

    One part of the records said manufacturer: Fairbanks-Morse, Model number: 18FM, HP 1.5m, pump capacity 18 GPM, length: 120 ft, diameter, 1 inch

    Then later on there is another report that has more info: Fairbanks 18R15212 (I believe that is what it says), 1.5 HP, 18 GPM

    Does this make any sense?
  16. mihomeowner

    mihomeowner New Member

    Messages:
    40
    Location:
    Michigan

    I'll take a look. The first thing I need to do is switch out the pressure gauge in my system, it's 10 years old and doesn't work very smoothly any more. But I am pretty sure that is an easy fix.

    Great info. After I fix the gauge I am going to try to move it to 40-60psi. Isn't this what most homes are at? Will this make my well pump cycle more during showers and general home water usage? Obviously showers are going to be a little nicer too :)

    Thanks for help
  17. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,826
    Location:
    NW Ontario, Canada
    A higher pressure will work towards overcoming some line loss (resistance) and increase the GPM. The higher pressure will also reduce the drawdown on the tank. Lastly, depending on where on the pump curve you are, the higher pressure may reduce the GPM output of the pump. So, as you can see, without the details filled in, the difference may or may not be negligible.

    A CSV would not care about the above details and give you consistently high pressure and stop most of the cycling.
  18. Wet_Boots

    Wet_Boots Sprinkler Guy

    Messages:
    798
    Location:
    Metro NYC
    Very wise move.
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