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Thread: Jet pump rapid short cycling at cut-out

  1. #16
    DIY Junior Member FRS's Avatar
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    just a question....why does that explain why it is cutting in at 40 when it should be cutting in at 20....am i right that anything in between should make no difference to the switch and, ultimately, the pump until it gets down to 20?

  2. #17
    DIYer, not in the trades LLigetfa's Avatar
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    You missed the explanation where the switch was not crossing the point of no return. Why not take the cover off the switch and watch it.

    Those switches are not marvels of engineering precision. They are also not designed to be mounted far from the tank. It might also have some sediment trapped under the diaphragm.

    Abandon the one mounted on the pump and wire in a new one at the tank.

  3. #18
    DIY Junior Member FRS's Avatar
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    ah ha! sediment. I don't think we have a location issue....never have before.

    granted, it was 10:30 at night so I didn't take the cover off the switch but sat on a rock pointing a flashlight at the gauge and watched it for half an hour. pretty well precisely every minute or so it would cycle....sat at exactly 40 lbs the whole time (except when it cycled of course) with no demand on the system....it was like it just felt like doing it. trust me, i've been around the block a few times with pumps....this one is just really strange.

  4. #19
    DIY Senior Member craigpump's Avatar
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    If there is no demand for water and the pump is cycling that tells me there is a pressure loss someplace.

  5. #20
    DIYer, not in the trades LLigetfa's Avatar
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    Quote Originally Posted by FRS View Post
    My jet pump (1/2hp) has started cycling very rapidly at the cut-out (40psi). Cycles perhaps 4 or 5 times in the space of a few seconds...pressure guage fluctuates rapidly with it and then shuts off and sits happily at 40psi.
    That description suggests that there are pressure pulses brought on by having the tank too far from the pump. The pressure pulses cause the contacts to bounce open and close. A waterlogged tank can present a similar symptom.

    That also suggests a switch that now does not latch open when it should. There is a fine balance point where once the contacts open, it should cross the point of no return, latching open until the pressure drops to 20 PSI.

    The fact that a minute later the cycle repeats is another symptom which suggests that either the pump went into thermal shutdown for the minute, OR there is enough of a pressure drop for the unlatched contacts to close.

    Sediment in the nipple can affect switch behaviour in a broad way. Sediment under the diaphragm usually affects the low pressure kick-in side of the operation.

    As I suggested before, abandon the switch on the pump and install a new switch at the tank Tee where it belongs.

  6. #21
    In the Trades Texas Wellman's Avatar
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    Gauges are not always accurate, even when new.

    The pressure the gauge "sees" may not be the same pressure the switch "sees". Sediment could be blocking one or both, but affecting each differently.

    You can put a larger line to the switch, but you'll still have 1/4" inlet/outlet piping. I've even seen where a large piece of pipe, 2" diameter, was used to subdue the pressure waves caused by cyclying.

    Good luck. My bet is that your gauge is sticking and not reading the pressure when it falls off through the footvalve or similar.

  7. #22
    DIY Junior Member FRS's Avatar
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    Thanks guys.

    Heading up tomorrow....new switch and new 3/4hp pump (maybe I'll just install it anyway...5.5 amp instead of 8.5 should get rid of my light dimming issue....) is in the truck (pain in the a** to run for stuff). I'll clean out the line to the switch and we'll see where we go from there....if I have to run for a small tank to install beside the pump i will....i know i have a new foot valve somewhere in the shed...

    Stay tuned....I'll get back to you Monday.

  8. #23
    Jack of all trades DonL's Avatar
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    Quote Originally Posted by FRS View Post
    Thanks guys.

    Heading up tomorrow....new switch and new 3/4hp pump (maybe I'll just install it anyway...5.5 amp instead of 8.5 should get rid of my light dimming issue....) is in the truck (pain in the a** to run for stuff). I'll clean out the line to the switch and we'll see where we go from there....if I have to run for a small tank to install beside the pump i will....i know i have a new foot valve somewhere in the shed...

    Stay tuned....I'll get back to you Monday.

    It sounds like you are going to replace a 120 Volt Pump with a 240 Volt Pump on a 120 Volt electrical feed.

    The current difference that you listed tells me this.

    240V is much better. The bigger the motor the more current at the same voltage it will require, not less.


    Good Luck
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  9. #24
    DIY Junior Member FRS's Avatar
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    Rocket....if I switched it over internally to 240 (keeping it on the 120 line) would my light dimming go away?



    Anyway guys, I tore the switch apart...membrane had a couple cracks in it (like what you would see on the sidewall of an old tire)....replaced the switch....in retrospect, cracks are probabably from all the switching on and off....but who knows.

    was marginally better.

    interesting though....now that I was able to sit in the daylight and watch it (without a 3 yr old and a 6 yr old buggin me) it was actually losing some pressure....would dip to say 36 or 37 lbs.

    had a new pump in the back of the truck (3/4 hp) :-)

    hesitated to open the box and actually spend the money when I knew I had a good pump sitting right in front of me....

    ran to town

    got a 5 gallon pressure tank

    mounted it directly on top of the pump. ya, i know the switch next to the other tank....meant farting around with electrical and i really didn't feel like it.

    anyway...problem solved.

    happy wife too.

    :-)

    guys, thank you for your wisdom regarding the location of the switch in respect of the tank....would have still been messing around with it and in the meantime would have spent 4 or 500 bucks trying to solve the issue (and not accomplishing).

    hats off to this forum!

    Cheers.

    so tell me something....plumbing guy at the hardware store (Home Hardware for you Canadian folk) tells me that PEX is no longer recommended for well applications??
    Last edited by FRS; 05-05-2013 at 06:13 PM.

  10. #25
    DIY Senior Member craigpump's Avatar
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    I don't think Pex was ever intended for well work although I have pics of a submersible hung on Pex with Sharkbites coupling everything together.

  11. #26
    Jack of all trades DonL's Avatar
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    Quote Originally Posted by FRS View Post
    Rocket....if I switched it over internally to 240 (keeping it on the 120 line) would my light dimming go away?

    I would say that it will help.

    You would have less voltage drop when the motor is starting and running.

    The pump motor would be more efficient running on 240V.

    You would have to connect it to a dual 240 breaker in the electrical panel.


    Be careful playing with electricity.
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  12. #27
    DIY Junior Member FRS's Avatar
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    interesting thing happened last weekend. lost power (storm) overnight on the friday night. power comes back on about 11 am saturday morning. water works very briefly, then nothing. then it comes back for a few seconds of dribble in the sink.


    hmmmm...

    go down to pump and it's at 20lbs. comes on by itself (like it should) and then cuts out pretty immediately. pump is pretty warm. drain the system and prime it again...works great...runs up to 40lbs. turn on the tap i have right at the pump and take it down to 20...turns itself on again and starts playing the same game. interesting and frustrating too. drain again...same play by play.

    so, get on the horn to some area plumbers. Finally between a few of us we piece it together (from the MULTITUDE of calls they were getting about pumps).

    Seems the hydro utility was only putting 71v through the system. Enough to make it run (sort of) and enough to power our lights etc, but NOT enough to run the pump properly. About 10pm that night (saturday) I knew they had fixed the issue when the lights in the cottage all of a sudden got a lot brighter. pump worked fine then.

    thought i would share. interesting lesson. glad we can always bucket flush. lol

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