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When the well pump for my sprinkler system turns on, it triggers the low-pressure cut-off on the pressure switch, causing the pump to shut down and leaving the system stuck in a low pressure state. The only workaround I have found for this is manually overriding it with the lever (shown in the image below) until the pump is fully operational. Is there anything I can do to prevent the system from losing so much pressure at startup like this?

https://www.youtube.com/watch?v=VZ7rGHzweYw&t=10

In this video, if the system were working as intended, the pump would stay on and continue to deliver water for the sprinkler's cycle. Instead, as you can see, it turns off immediately.

Maybe, this is happening because:

  1. The sprinkler system's initial demand is high (repressurizing all the sprinkler lines, they're a little leaky)
  2. The pump takes some time to reach its normal operational speed and output.

The tank and switch are both completely new, so I'd doubt that there's any component failure. I've also charged the tank to 38 PSI (about 2 PSI less than the cut-in pressure for the switch). I've also fiddled a ton with the cut-in/off settings screw of the switch, both going up and down, and nothing seems to work.

Does anyone have any recommendations on how I can fix this?

I am getting a delivery of a non-cut-off switch soon, which I plan to install with some reluctance: I do believe that a cut-off is generally beneficial, but in my case, it seems to be contributing to the problem.

pump/tank setup pressure switch and lever

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  • With that tiny tank, does the pump switch off and on a lot in use, or does it just run without ever getting to cut-out pressure until the end of the cycle? Are the leaks such that the tank maintains pressure between sessions?
    – Ecnerwal
    May 30, 2023 at 3:05
  • The pump runs during the entire sprinkler cycle, no flickering, which I suppose is kinda lucky that pressure is staying nicely within range during operation. Regarding pressure maintenance between sessions, it does seem to hold (the leaks I refer to are beyond the sprinkler valves), but it just shuts down each time when a new session starts.
    – t-mart
    May 30, 2023 at 3:15

2 Answers 2

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That is a laughably small tank, so replacing it with a much larger one would solve the problem by providing adequate water storage to cover that initial pipe-filling stage without going utterly flat.

However, a replacement shallow-well pump for the case where you wish you'd had a low pressure cutout is probably less expensive than a tank of adequate size for the job (hint - it will set on the floor, not mount on the pipes, and you don't want the smallest of those, either.)

Edit: As you have clarified that the pump runs the entire time the sprinklers are on, you don't need a larger tank for the usual reason of adequate cycle time. So, the only use a larger (and more expensive) pressure tank would be is the initial fill of the system without dropping below cutoff. If you have not had problems with no water, it may not be worth buying a larger tank to maintain the low pressure cutoff for a pump that might be less expensive than the tank allowing it to be protected.

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  • Heh, yeah, I have no background in this kind of work, so I'm not sure what capacity tank is adequate. I do know though that, in my research, much larger tanks were used when they were serving water inside the home. Conversely, here, I'm just doing the sprinklers. Additionally, this is the same capacity tank that the last homeowners had installed (and I'd reckon they hired someone for that install). Not to say your advice is incorrect, I'm just telling why it is how it is.
    – t-mart
    May 30, 2023 at 3:17
  • Ah, are you saying this isn't the right pump for shallow wells? Also, I don't think I mentioned if this is a shallow well or not (nor do I even know the answer). Is something else revealing as such?
    – t-mart
    May 30, 2023 at 3:24
  • You have a surface pump with one pipe to the well. Therefore, it's a shallow-well pump. I'm saying that if that pump works for you, a replacement pump (if it dies from running dry) may cost less than a large pressure tank will.
    – Ecnerwal
    May 30, 2023 at 11:29
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If I were to re-do this I'd get a much larger tank. 2 other thoughts: you may be drawing more water than the well can produce causing the pump to shut down. Next: Some sprinkler system controllers can be set to have a delay between zones watering giving the pump enough time to recharge the larger pressure tank between watering zone timing.

Lots to consider here:

  • what is the gpm of the pump?
  • what is the capacity of the well?
  • How many GPM is needed per zone?
  • How long does each zone run?
  • Can your sprinkler system controller be programmed to pause for a few minutes between zones?

All of this needs to be balanced, every well and pump are different, esp. wells. While not easy, you need to do the calcs and size/time all your system to "play nicely" with each other.

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  • Thanks George. I think I'm due for a larger tank!
    – t-mart
    Jun 1, 2023 at 6:11

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