Booster pump stops then restarts

Discussion in 'Pumps and Tanks Well Forum & Blog' started by gs2005, Jun 5, 2005.

  1. gs2005

    gs2005 New Member

    Messages:
    10
    I'm a newbie to this forum so please bear with me.

    I have installed a new sprinkler system. I ran it yesterday for about an hour (at about 12 gpm) and then water flow stopped. The booster pump had stopped running and the pressure gauge showed "0". I switched it off for about an hour. When I turned it back on it kicked back in like nothing had happened. I am looking for advice before I start troubleshooting.

    Here is the configuration: My well pump feeds a very large (about 5000 gal) holding tank which feeds the booster pump (an existing 2hp pump) that feeds a pressure tank (set to 60/75 psi).

    When I turn on the sprinklers the pressure tank draws down and the pressure stabilizes at about 55psi which runs the sprinklers at 12 gpm quite nicely.

    My uneducated guess is that the pump overheated and after it had time to cool down ran again?? I don't know how old the pump is (came with the property). Is this usual?

    The second possibility is that there is a problem with the holding tank - that it is not filling and the pump ran dry, but that somehow seems less likely to me.
  2. Pumpman

    Pumpman Pump Sales

    Messages:
    191
    Location:
    So. Cal
    Most pump motors have internal overloads that will shut the pump down if it overheats. It is very possible that is what happened in your case.
    Another possibility, which you mentioned, is that the pump did indeed run out of water. Some pressure switches have a builtin low pressure dropout, that protects the pump from running dry.
    Try to ascertain whether or not there is plenty of water in the tank, should the pump quit again.
    Ron
  3. gs2005

    gs2005 New Member

    Messages:
    10
    Shouldn't a pump be able to run more than an hour without overheating?

    Thanks, Pumpman. Time to get on a ladder and peer into the tank.

    But if it turns out that there is water in the tank, what do I do about the pump? Shouldn't it be able to run for a few hours continuously without overheating? I guess I could set up the sprinkler system so that it never runs for more than 45 minutes at a time without taking a break.

    Or maybe I could lower the pressure settings to say 30/50 (and the pressure tank air pressure accordingly) which should give the pump a chance to cycle off intermittently (does this make sense?) I don't know why the previous owners set it so high - maybe because it is 300 feet from the house. Would that result in enough pressure loss to warrant such high pressure settings?

    Or I could put higher flow nozzles on the sprinkler heads which will allow them to dump more water in a shorter time, relieving demands on the pump. That will also run the system at lower psi. Will that relieve pressure on the pump, or doesn't it care about the psi?

    Or is it time to get a new pump?

    Sorry if some of these questions are naive - I am trying to learn.
  4. Pumpman

    Pumpman Pump Sales

    Messages:
    191
    Location:
    So. Cal
    The pump motor should be able to run continuously without overheating. Setting the pressure so that the pump will cycle on and off will make the problem worse. The hardest time for a motor is starting up. The windings get extremely hot, which damages the winding insulation, which causes the motor to overheat and so on.......
    Motor life is measured in number of starts, not run time.
    If it's not a loss of water in the storage tank that causes the pump to shut down, it may be time to consider a motor change.
    Ron
  5. gs2005

    gs2005 New Member

    Messages:
    10
    Tank is fine - it must be the pump

    Looked into the holding tank today - it is full and refilling quickly when drawn down.

    I ran the sprinklers again and again the pump shut off, this time after about 50 minutes. The casing was very hot to the touch, so I think it is a good guess that it is overheating. 25 minutes later it was ready to run again.

    So I guess I'll replace it. Could something in the configuration of the sprinkler system be causing the problem? I'd hate to replace the pump only to discover a new pump has the same issue.

    There is nothing fancy about the sprinkler set up. The main pipe to the sprinklers comes off the end of the pump manifold that is after the pump/pressure tank. That pipe is a 1.5 inch line, goes through a backflow device, and into a valve manifold. One inch pipes come off of those and run about 150' to rotor sprinkler heads (5 or 6 per valve) with total flow rate per zone of about 12gpm. Seems pretty standard from what I've read ....
  6. Gary Slusser

    Gary Slusser That's all folks!

    If you actually have the pressure switc hset at 65/70 was it? and the pump stablizes at 55... I think there's a clue in there but I'm too tired to see it just now.

    But I don't think it has much to do with the pump or it probably wouldn't run 50 minutes. I think it's the water supply or something sucked up against this pump's inlet in the tank. This is a jet pump outside the cistern right?

    Gary
    Quality Water Associates
  7. gs2005

    gs2005 New Member

    Messages:
    10
    Setup

    Yes, the pressure switch seems to be set at about 60/75 (from observing the pressure gauge). The setup is as you describe: a holding tank feeds the booster pump which is connected to a pressure tank.

    I will check, but I'm pretty sure that the system settles into a psi (around 55) which is lower than the psi when the pump kicks in initially. The flow should be around 12gpm based on the sprinkler head manufacturers specs (at what I guess the actual pressure at the sprinkler head to be (based on the pressure loss calcs in Stryker's tutorial)).
  8. Gary Slusser

    Gary Slusser That's all folks!

    What is the output of the pump supposed to be at 65 psi? Most jet pumps will strain to keep up with that pressure switch setting and gpm output. I doubt it has been shutting off during the sprinkler run.

    Gary
    Quality Water Associates
  9. gs2005

    gs2005 New Member

    Messages:
    10
    Reply to Gary

    You are right that the pump has been running continuously. I haven't measured the water flow at the sprinkler head. According to the manufacturer's chart, the nozzles I have should put out about 13.5 gpm per zone. (They are spraying to about the specified distance, so this estimate is probably about right.) I also don't have the original manual or flow/pressure chart as it is an old pump that came with the property.

    Are you saying that a well-functioning pump should not be able to run continuously at this psi and flow? What I am thinking I might do is set the sprinklers to run in cycles, 30 minutes on and 30 minutes off. That should give the pump a chance to cool off intermittently. Does that plan make any sense, or should I be looking to invest in a pump that is optimized to my situation and that can run continuously?

    I really appreciate your patience and advice!
  10. Gary Slusser

    Gary Slusser That's all folks!

    No I'm not, pumps are made for continuous duty. So I still think you have a water source problem, or IOWs the pump shouldn't overheat as to where the thermal overload would shut it off if it were getting the water it wanted.

    Since it is, it isn't getting the water it wants or there is a seal or bearing that is bad and generatiing heat in the motor. Or the environment is too hot or the pump is out in the sun etc.. Check for dirt sucked into the motor preventing cooling.

    Shortening the time of the sprinklers should help, but that heat is killing the pump motor.

    Gary
    Quality Water Associates
  11. gs2005

    gs2005 New Member

    Messages:
    10
    There is a plentiful supply of water. The pump is 8 feet away from a full 3000 gal tank. There is a 1.5 inch pipe from the tank, that narrows to one inch after the filter (see below) to match the pump inlet size. The water coming out of the bottom of the tank appears to be clean - at least there is no noticeable silt and the filter does not get dirty quickly.

    The filter (one of those kinds that has a large replaceable cartridge) is about 12 inches before the pump inlet, on the inlet side of the pump. The cartridge is new, but I wonder if the the filter could be a drag on the motor?

    You suggest I check for dirt in the pump that is preventing cooling. How do I go about doing that?

    Is it possible the pump has just reached the end of its useful life? It is a Gould HSC 20 with a Smith motor. Nothing comes up when I Google that pump model which makes me think it is pretty old.

    I ran the sprinklers for 30 minutes today. The system ran at 60 psi (probably putting out about 14-15 gpm with excellent pressure at the sprinklers). The body of the motor was quite warm after 20 minutes. The hottest part of the motor is around the middle of the motor housing.

    The pump is in the shade outside and it was reasonably cool when I ran it, so environment isn't the problem. Also, 30 minutes after running the pump the motor housing had cooled down some but it was still pretty warm. So cycling the pump will help but isn't the answer.

    I would be quite happy to pull the pump apart if a visual inspection (by a neophyte) might reveal a broken seal.

    Any advice greatly appreciated.
  12. gs2005

    gs2005 New Member

    Messages:
    10
    Ok, I found the pump opn the Goulds site. It is a current pump. It is a 3-stage pump that can generate 15gpm at 200 ft of head - so plenty powerful enough for this application.
  13. Pumpman

    Pumpman Pump Sales

    Messages:
    191
    Location:
    So. Cal
    I'm still guessing that there is a problem with the motor that the thermal overloads are tripping out on.
    You might want to check the voltage at the pump and see what the amp load is when the pump runs.
    Low voltage will make a motor run hot.
    Ron
  14. Gary Slusser

    Gary Slusser That's all folks!

    You've got a filter on the suction line and haven't mentioned it until now... lol

    That filter may not look dirty but if you remove it.... I'll bet ya a beer that your pump doesn't get hot any more. Or just humor me and remove the cartridge and run another 30 minute trial. IMO the cartridge is a not flowing the water the pump wants and that's why the pressure is running below the 65 cut-in. Or said another way, the pump seems to not be getting enough water. IMO the filter is a bad idea, and if the pump builds pressure and stays relatively cool without the cartridge, leave it out of the housing. If you want a filter, install it after the pump.

    Let us know what happens.

    Gary
    Quality Water Associates
  15. gs2005

    gs2005 New Member

    Messages:
    10
    Problem Resolved!

    Gary, I pulled the filter cartridge out and ran the pump for 30 minutes. No change. It ran at 55 psi and was hot quickly.

    So I relented and called in a pump expert. He first checked out the voltage/power consumption. Pumpman, you were completely correct. The motor is rated to a maximum of 13.2 Amps but was running at 14.5. Closer inspection revealed two (probably related) problems. First the power switch was malfunctioning, reading 230v on the wires coming in but sometimes only 110 on the wires going out. Some kind of short in the switch, probably caused by the second reason, which was a short on the wires going into the pump. One of the leads had some small cracks in its insulation.

    He cut off the last few inches of wire and then reconnected to the motor. Replaced the power switch. Now the motor is drawing only 8.2 Amps. No doubt the difference will cause the overheating.

    The pump is now running the sprinklers at 78 psi! (Yes, I had to increase the pressure cut-out setting). Even with an estimated 25 psi loss between the pump and rotors (long distance plus a backflow preventer), that's more than 50 psi at the sprinkler heads. The rotors think they've died and gone to heaven. Of course had I known I had that much capacity I would have designed greater flow per zone, would likely have used less power(?) Still, I can hardly complain.

    The pump expert agreed there is no good reason to have a filter on the inlet and good reasons not to, so I have left it out. Probably partly responsible for the amazing performance.

    Anyway, thanks to both of you for your patience and help.
  16. Gary Slusser

    Gary Slusser That's all folks!

    Well I owe ya a beer... but I learned something so thanks for the feed back.

    Gary
    Quality Water Associates
  17. gs2005

    gs2005 New Member

    Messages:
    10
    The way I figure it, I owe Pumpman a beer for putting me on the right track and you owe me a beer, so cutting out the middleman you owe Pumpman a beer :)
  18. Gary Slusser

    Gary Slusser That's all folks!

    I'll go along with that.

    Gary
    Quality Water Associates
  19. Pumpman

    Pumpman Pump Sales

    Messages:
    191
    Location:
    So. Cal
    Can we make it a 40? :)
    Glad to hear the issue has been resolved.
    Ron
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