Pump fail on SQFlex, replace with 115vac inverter driven?

Discussion in 'Pumps and Tanks Well Forum & Blog. Water is life.' started by Hal_Ferguson78, Oct 10, 2018.

  1. Hal_Ferguson78

    Hal_Ferguson78 New Member

    Joined:
    Oct 10, 2018
    Location:
    South Mendo Coast, CA
    Greetings Forum!

    My Grundfos Model 3 SQF-2 pump (part of their SQFlex system with CU200 controller and provided PV panels) has failed and am considering replacing the pump with a 115vac single phase pump of 1/2 HP or less. I pulled the pump, know that the cable is good, and that the pump wouldn't start on 115 vac when placed in a large tub of water. I don't have first hand knowledge of what precisely failed, though the Sonoma County pump and drill outfit tells me that "the motor is fried." I'm hoping to avoid the cost of purchasing a new 3 SQF-2, prices for which have ranged from $4,400 from that pump outfit to $2,100 online.

    We now have an off-grid PV-based system with what my numbers tell me is of adequate capacity to support a 115vac single phase pump of say 1/2 hp or so. I have 10,000 gal storage capacity so I don't need to pump a lot in a hurry -- if I can pump 3 GPM for 35 hours in a month's time, I can cover my highest monthly water use on record. I think I can do that during periods of full sun after the batteries have hit full charge, even after derating the PV panels due to age. As an aside, the cable from the tank float switch is bad; it shows the tanks full after it's been raining, so we've just told the CU200 that the tanks are not full by disconnecting the float switch input and manually turning the pump on and off at the CU200 periodically.

    The questions are:
    1) What pumps out there will run on my inverter-based 115vac, push a 330' head, be controlled from what amounts to an ON/OFF switch, survive being turned off regularly for a stretch of a week or two, have built-in dry run protection or shut off, and last more than 10 years?

    I've looked at:
    Sta-Rite HS Submersible Well Pump, S5P4HS05121
    Gould 1/2hp 115v 2wire, 5G05412C
    Franklin Tri-Seal 4400, 5JS05P4-2W115

    I couldn't find a Grundfos 115vac solution.

    2) Should I be bothering with any of this? That is, should I just suck it up and buy the dang Grundfos 3 SQF-2 and expect to do it again in 10 years?

    Well Info
    Casing: 5-inch ID PVC, blank to 120', perforated 120' to 260'
    Static Water Depth: 120'
    Estimated yield: 2 GPM
    Pump depth (former): 230'

    Water Storage
    Two series connected 5,000 gal storage tanks approx 100' elevation above house and wellhead.

    Power Source
    Outback 24v system of 2 parallel strings of quantity 4 L16 batteries and quantity 8 210w PV panels with a VFX3524 Inverter / Charger producing 115vac capable of a peak 70A AC for 1 mSec and 50A AC for 100 mSec and continous AC RMS output of 29.2A AC or 3500VA. My existing system can not produce 230vac.
     
    Last edited: Oct 11, 2018 at 2:10 PM
  2. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    3-wire pumps draw less power. You might be better that way, even if you have to change wire.
     
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  4. valveman

    valveman Cary Austin Staff Member

    Joined:
    Mar 15, 2006
    Occupation:
    Pump Controls Technician
    Location:
    Lubbock, Texas
    Any of those pumps will work. They do make a 115V 5S05-13 Grundfos, and like Reach says a 3 wire motor will be easier to start. You will just need a control box and 4 wires down to the pump. Here is a 115V Grundfos, which is the best of the ones you mentioned. I would not use the Franklin or the Sta-Rite, as they have "floating stage" design and don't work as well at low flow rates. As a matter of fact Franklin says their pumps are no good below 5 GPM, so they should just say they are no good period.

    Here is one I found
    https://www.amazon.com/dp/B00O29GT50/ref=psdc_3226975011_t3_B00O29IYN0
    You will also need this control box.
    https://www.amazon.com/Franklin-Ele...261639&sr=1-1&keywords=1/2HP+115V+control+box

    Even buying new wire it will be a fraction of the cost of that Flex pump, as they are very expensive, and not necessarily worth it.
     
  5. Hal_Ferguson78

    Hal_Ferguson78 New Member

    Joined:
    Oct 10, 2018
    Location:
    South Mendo Coast, CA
    Ah, thanks Reach. I was fixated on the two-wire solution to keep from having to change out the existing cable, but drawing less power especially at start up, should be a prime consideration.
     
  6. Hal_Ferguson78

    Hal_Ferguson78 New Member

    Joined:
    Oct 10, 2018
    Location:
    South Mendo Coast, CA
    Thank you very much Cary for the great info. You're a national treasure, or at least a forum one. I'll verify with Outback that the inverter, PV panels, and battery bank will support that Grundfos pump. If I understand the Grundfos literature, the associated pump MS 402 will draw 42.5A AC at start up. Thanks again and I'll keep you posted. Thanks for making your tip jar available; I may just find my way to making a donation for the cause.
     
  7. VAWellDriller

    VAWellDriller Member

    Joined:
    Sep 8, 2012
    Occupation:
    Mud rotary well driller, pump installer
    Location:
    Richmond, VA
    Did you try the sq flex in the well on 115 power? I've worked on a few of them and the pump/motor was NEVER the problem....always controller or wire or something else. They have a dry run sensor on the motor lead that really needs some submergence to work properly in a test tank. Grundfos makes a regular SQ pump, 1/2 HP 5 gpm that will almost make the head that you need. It has a soft start and a very low current draw at startup....I run one on a cheap vector 1000 watt inverter in my service truck. A lot of people knock the 3" grundfos pumps; I've pump in a LOT of them over the last 10 years; I never use the grundfos controller, always just run on pressure switch. I have never had even one go bad. Most of them I have installed are going in nasty/rusty 4" steel wells that are crusted up too bad to get a 4" pump in.
     
  8. Hal_Ferguson78

    Hal_Ferguson78 New Member

    Joined:
    Oct 10, 2018
    Location:
    South Mendo Coast, CA
    Thanks Mr. VA Well Driller. Good to hear your positive experience with the Grundfos 3-inch pumps. The short answer to your question is yes.

    I checked power to the submersible cable leads at the CU200 on both solar PV power (77vdc) and house power (115vac). I pulled the pump, cut the cable at the pump lead / cable junction, verified continuity of the 3-conductor submersible cable, stuck the pump in a large tub of water with the dry run sensor submerged (though only by a couple inches), wired the pump up to 115vac and plugged her in. Still no go. Had a buddy drop it by Weeks Pump and Drilling in Sebastopol for their diagnosis and, though I'm hoping for more detail, they report the pump is inop (they point to the motor), having applied both 110vac and 220vac without effect.

    I didn't have success using the on-line Grundfos pump selection tool for a 115vac solution, though I'd narrowed my search to a two-wire configuration. Cary's pump suggestion, the 5S05-13 looks promising, but I'll take another look at that SQ pump because start up current is an issue.
     
  9. Hal_Ferguson78

    Hal_Ferguson78 New Member

    Joined:
    Oct 10, 2018
    Location:
    South Mendo Coast, CA
    I may be looking at the wrong material (SQ Pump Lit), but from what I can tell, the SQ and SQE pumps require 200-240 V - 10 %/+ 6 %, 50/60 Hz. My existing inverter only makes 115vac. I'm hoping for a solution that doesn't require a step-up transformer or another inverter. If you know of a Grundfos SQ pump that runs on 115vac, please do let me know.
     
  10. valveman

    valveman Cary Austin Staff Member

    Joined:
    Mar 15, 2006
    Occupation:
    Pump Controls Technician
    Location:
    Lubbock, Texas
  11. Hal_Ferguson78

    Hal_Ferguson78 New Member

    Joined:
    Oct 10, 2018
    Location:
    South Mendo Coast, CA
    Well crapola. I couldn't find a 115vac SQ series pump on their website. Thanks for the info on this one.

    Outback Power did get back to me: "Looking at the specs of this water pump (the Grundfos 5S05-13 4-inch 3-wire), it should work with the inverter you currently have. The only thing I worry about is the start amps of 42.5a. It really depends on the depth of the well on how fast the start up will be for the pump. I would recommend adding a soft start to prevent any issues you may have with a starting surge."

    Well, the start amps was the thing I was worried about too. Rather than muck around with a soft-start controller for the lower speed 4-inch 3-wire pump, which would also necessitate replacing the 230' of cable, it looks like the 3-inch high speed pump will be the one.

    Now. Do you suppose I can use the existing CU200 to simply turn the pump on and off from the 115vac source?
     
  12. VAWellDriller

    VAWellDriller Member

    Joined:
    Sep 8, 2012
    Occupation:
    Mud rotary well driller, pump installer
    Location:
    Richmond, VA
    Throw the controller away...just use float switch or light switch to cut it on and off. You can save some $$$$ buy a sq instead of sqe model. The sq is fixed speed run only but that's fine for your situation.
     
  13. Hal_Ferguson78

    Hal_Ferguson78 New Member

    Joined:
    Oct 10, 2018
    Location:
    South Mendo Coast, CA
    Alright. A simple switch will do the trick. Thanks again. Will post a closing note when get the pump installed.
     
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