Pump Cycling Question

Discussion in 'Pumps and Tanks Well Forum & Blog' started by Marc46, Jan 1, 2009.

  1. Marc46

    Marc46 HVAC Contractor

    Messages:
    102
    Location:
    Central Florida
    I have a submersible pump,......I believe it is a 1 hp, but not positive.
    Running a 40/60 pressure switch and a bladder tank along with various filters, and softener.

    A couple of days ago I changed the non-functioning pressure gauge and slightly adjusted the switch settings to get a true 40/60 range.

    Drained the system down, and checked the bladder tank pressure. It was only about 18 psi, so I added air up to 38 psi. The bladder tank is fairly old but it seemed to take the charge, and also no water coming out of the schrader. It says 33 gal capacity, but the drawdown rating is not readable any longer. I presume the low air charge could be from loss through the rubber over the years,.........I admit I have not checked the pressure for a very long time.:(

    Onto the real question!
    With no water being used in the house, I used a hose to drop the pressure to 40. Close the spray handle and the pump brings it back to 60 perfectly.
    A plumber friend of mine says that my pump is shutting off too quickly, and that the pump needs to run for a minimum of 60 seconds in a fill cycle for proper cooling.

    From pump start at 40 psi cut-in,........it only takes it about 20 seconds to reach the cut-out of 60 psi with no water being used anywhere. Sounds to me like everything is working correctly, but he says no, and that I need a much larger bladder tank.

    Is he correct, or is he nuts, and everything is normal?
    Thanks for any info provided!:)
  2. Gary Slusser

    Gary Slusser That's all folks!

    Pumps up to 1.5 hp need a minimum of 60 seconds OFF to cool properly before starting again. The tank's draw down gallons, at the pressure range you run the switch at, and the higher the settings, the lower the draw down and shorter time the pump will be off, is what is used to correctly size a pressure tank; it's based on the output of the pump.

    That can get you up into serious bucks for the size tank that will allow that 60 seconds. Or you can use a very small tank and a CSV (Cycle Stop Valve) that provides constant pressure and greatly reduces the on/off cycling of a pump and spend a small fraction of the cost of a larger tank.
  3. Marc46

    Marc46 HVAC Contractor

    Messages:
    102
    Location:
    Central Florida
    Thanks Gary,.......that makes a lot more sense to me.
    I did NOT misunderstand him, as I said "Aren't you referring to the off-time?"
    He said no, and that the motor cools from the water flowing through it.

    It doesn't short cycle per se, where the contacts snap on and off.
    I will need to check the drawdown time though, as I am not certain it would be off for 60 seconds with enough water being used in the house. It sure does pump up fast though,........even when water is flowing to several things at a time. I figured that was good.

    Do you think that 33 gallon bladder is too small?
    Also if you don't mind what is a CSV, as I am not familiar with them, even though I am quite mechanical being an HVAC contractor.
    Thanks!
  4. Gary Slusser

    Gary Slusser That's all folks!

    You said the pump was on for 20 seconds; it won't be off for 60 seconds during your peak demand water use. And if that is true, that is short cycling the motor and shortening the life of the motor/pump, it doesn't have to be on/off, anything less than 60 seconds is short cycling.

    Water does not go through the motor.... the water around it cools it. And water comes into the pump inlet between the motor and wet end of the pump ABOVE the motor. The motor is on the bottom of the pump. Water flow is from the static water level down to the pump's inlet; unless you have a screened well and the pump is set in a screened area based on the pumping level of the well. You probably have a rock bore well.

    It sounds as if you may have an over sized pump.

    33 gallons etc. doesn't matter, you measure by seconds off based on the pressure range the pump is set for.

    www.cyclestopvalves.com,
    Last edited by a moderator: Jul 10, 2011
  5. Marc46

    Marc46 HVAC Contractor

    Messages:
    102
    Location:
    Central Florida
    You may be right about the pump being oversized.
    Without going out and measuring, I think I have a 4" casing, and all I remember is that the pump is hanging at around 75 feet. I am in Florida, and we typically don't have deep wells here unless the water is bad.

    The house is a bit over 16 years old. I think the original pump was a 3/4 horse, and it went out around 3 years after moving in. Myself and a friend replaced it by hand,.........what a thrill!
    That one went out around 2000 to 2001 from a lightning strike I believe.
    All I remember is it was grounded when I tested it, and it was right after a very bad lightning storm.

    My mother, and step-dad had just come up here from S. Florida, and moved in with me while they were building a house when it went out. He didn't want to see me break my back again, so he paid half to have a well guy do the work.

    All I remember is he suggested a larger pump, and I am certain it was either a 1 HP, or possibly a 1 1/4 hp pump.
    This is the pump that is still running now.

    I also noticed that for awhile I am getting a buzzing sound in the pipe coming out of the casing when the pump runs. If I put pressure on the pipe, it stops. It is a "vibration" type resonation,..........best I can describe it.

    Thanks for the links BTW. It appears that these devices go in the drop pipe per se, and would require a well man to do the work.

    Last question,........is it possible for me to go with an above ground "jet-pump" and avoid all of this back breaking pulling of the submersible when things go wrong?

    Any pros, or cons to that idea?
    Thank you very much for your time!
  6. Gary Slusser

    Gary Slusser That's all folks!

    No the CSV can go in the drop pipe or the line to or at the pressure tank.

    There is no way I'd go to a jet pump if I could use a submersible. Subs are much better but yours is way oversized unless you are doing irrigation in addition to feeding the house.
  7. Marc46

    Marc46 HVAC Contractor

    Messages:
    102
    Location:
    Central Florida
    I guess I need to call one of the folks connected to the links you sent.

    I do not have an irrigation system, so if this pump goes,......which it surely will at some point,........I presume I should go back with a 3/4 hp?

    It is a large 3 bedroom 2 full baths.
    About 2450 originally, and I closed in the garage for a spa/weight room.
    County has me at 2875 of living space.

    2 toilets, 2 showers, 2 tubs, 4 sinks including the kitchen, dishwasher, washing machine, ice maker, and an RO system on the kitchen sink.
    That is all of my potential water consuming devices.

    I am going to time the drawdown cycle in the next day or 2 to see what it is.

    Thank you once again.
  8. masterpumpman

    masterpumpman New Member

    Messages:
    729
    Location:
    Virginia Beach, VA
    Install a Cycle Stop Valve!

    Most plumbers aren't experienced pump technicians. . . but a few are!

    Install a CSV anywhere between the pump and the tank. It will give you a constant pressure (like city pressure) and it will prevent your pump from cycling.

    Personally I prefer the adjustable CSV over the non-adjustable (plastic valves), however they cost a little more. If you purchase a non-adjustable plastic CSV, I would recommend the CSV-150. It will give you 50 lbs. of constant pressure.

    If and when you have to replace the pump you may prefer to go back to a 3/4 hp, but keep the Cycle Stop Valve in the line.

    Your wife will love the constant pressure! Contact www.cyclestopvalves.com to locate a supplier in your area.
  9. Marc46

    Marc46 HVAC Contractor

    Messages:
    102
    Location:
    Central Florida
    Thanks guys,......I will call one of them by Monday.

    I have read about them and now I understand how they work, I believe.
    Where I am confused is how does this remedy my issue of the pump not being off for at least 60 seconds?

    Maybe I am missing something, but it sounds like with one of these, it will keep the pump running continuous while water is being used at the minimum GPM rate,.........I have that part.

    Now I quit using water for 10 seconds say, and then turn something else on again. Isn't the pump still going to start again as soon as the 40 psi cut-in is hit?

    I guess the purpose is to cut down the number of starts, and stops in a given day which makes sense, and not having the fluctuations would be nice also.

    I also presume I could install this in the tee feed going to the bladder tank?
  10. Gary Slusser

    Gary Slusser That's all folks!

    When you stop using water the tank refills and if you start using water before it is filed the pump keeps running, if the pump has shut off, you get the draw down gallons out of the tank and then the pump starts.
  11. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    Where in Florida are you? I'm in the Tampa area and all of the Drillers around here don't know there is such a thing as a 3/4 or 1/2 hp pump. They all use 1 hp for some unknown reason. I am probably the only one in the county who sells 1/2hp pumps. You probably did need a 1/2hp or 3/4hp for your application. Since you have the pump now, I would take Garys and Porky's advice and use a CSV. That will solve your problem.

    Quit listening to your Plumber friend. If he really thinks water flows through a submersible pumps motor, you would be showering in sparks instead of water droplets.;)

    bob...
  12. Marc46

    Marc46 HVAC Contractor

    Messages:
    102
    Location:
    Central Florida
    Speedbump,.....I am north of you in Ocala.
    I know the original pump was a 3/4 for sure, as I was the one to replace it.

    It got changed the last go round when a well guy replaced it. I remember him telling me I needed at least a 1hp pump.

    What's a fair price nowadays for replacing a submersible at 75 feet?
    Just curious for when the time comes.
  13. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    We were just discussing giving out of pricing on Forums. The general concensus is that pricing varies from one area to another and one mans quote may be far different than the other mans quote. The other thing is the Apples for Apples thing. Too many variables. Best thing is to shop around up there and see what the going rate is. Be careful what you are getting. If you can't get it in writing, I would stay away from that guy.

    bob...
  14. Marc46

    Marc46 HVAC Contractor

    Messages:
    102
    Location:
    Central Florida
    I can understand that,......it happens to me also. I get friends from down south asking me how much a new A/C system should cost all the time.

    Hopefully it will last for awhile anyway.
    Then let me ask this question,........what brand of pump do you folks recommend?

    That shouldn't be a problem,.....right!;)
  15. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    I like the Betta Flo. They are made in Georgia, the company isn't owned by ITT or Pentair and they use Franklin motors unlike the Big two.
    bob...
    Last edited by a moderator: Jul 10, 2011
  16. masterpumpman

    masterpumpman New Member

    Messages:
    729
    Location:
    Virginia Beach, VA
    Best pump!

    Speedbumb sells Betta Flow pumps and I like them. I knew the people that started Betta Flow years ago. They build a good reliable pump.

    However there are other good pumps out there! Just purchase a major manufactured pump and preferably not from a home improvement store. Stay away from a VFD pump.
  17. Marc46

    Marc46 HVAC Contractor

    Messages:
    102
    Location:
    Central Florida
    OK guys,......now another question!
    I just looked at the site posted, and the pump section.
    How do I figure out what I have as far as the GPM curve?

    Take a couple 5 gallon paint buckets, and see how many a fully opened hose will fill in one minute?
    I presume this relates to the capacity of the well so that the pump does not overrun the supply water?

    Yes,.......I know I am a pain!:D

    BTW: I think I paid right at 900 bucks for the whole job last time, and it was done around 10pm at night,......guess that wasn't too bad.
    The one I replaced myself years before, I got from Ferguson where I had an account for boiler parts. I think that pump ran me about 200 bucks. That was a long time ago though. I don't want to replace another one by hand anyway.
    Last edited: Jan 2, 2009
  18. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    The garden hose method will only tell you how much water can come out of a hose bibb and a garden hose. Not what the well and pump will do.

    Remember that pipe size is a big factor in gallons per minute and pressure and pressure loss. If you want to figure out how much your well pump can do, you will have to unhook it at the well at the pipe that leaves the well (size matters) and do a bucket test there. Let the pump run open discharge for 10 - 15 minutes to let the water level stabalize. Then do your test. If you want to get fancy, you can install a ball valve with a gauge so you can pressure it up to 40 - 50 lbs to see what it will do at sprinkler pressure. This is the best way.

    bob...
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