Low-amperage, small diameter pump for a 70 foot well depth?

Vigi

New Member
Greetings, I'm new here.
I have "typical" residential/suburban well: 5 inch bore, water level at about 40-60' below grade, pumped with a 120VAC 1/2HP pump that goes to my pressure tank. The submerged pump is about 80' below grade. It works fine, but I'd like to have a backup ability to get water if we lose grid power. I'd like to avoid a big investment or disrupting my "normal" pump and piping.
Ideally, I'd like a small (1" to 1.5" dia) DC pump that I could just put down the well in the space between my existing poly-pipe and the well casing. I could leave it there all the time, or drop it in when needed. A flow of just a few GPH would be plenty, and I could run it in the daytime with a solar panel and no battery (or, charge a battery and pump with that). As long as the weather isn't freezing, the pipe (probably 1/2" flexible vinyl) could exit from the top of the casing to a cistern.

I haven't had much luck in finding an appropriate pump. The closest I've come is these small DC pumps built for well sampling applications (I have no affiliation with this retailer or manufacturer). (I'll avoid a link since I'm a newbie. "Proactive pumps" makes them)

They are small and run on 12VDC, but seem a bit pricey at about $150 and up. Also, not particularly robust (the mfgr warns against constant use, and the motors have a reported life of 400 hours).

Pumping to the surface from 70 feet or so is only a head of about 30 PSI, so I'd think a simple 50 psi diaphragm pump would be fine and probably sturdier than these turbine pumps. But, they don't seem to be available in small diameter sizes.

Any other ideas for this application? If I can't find a small DC pump, I'll probably need to go with panels, batteries, and a beefy inverter big enough to handle the start-up amperage (36A or so) of my existing 1/2HP 120 VAC pump. That seems like a long and expensive road to go down for just 20-30 gallons per day.

Thanks for any ideas.
 
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newbostonconst

Solar Addict
I would put your money and energy into buying an inverter that will run your current pump. The the inverter could also be used to power other things when not pumping.
 

time2roll

Photon Sorcerer
Have you looked at water storage tanks? They seem to run about 50 cents a gallon. You then use a small 12v or 24v DC water pump to supply the house if needed.
 

Vigi

New Member
Have you looked at water storage tanks? They seem to run about 50 cents a gallon. You then use a small 12v or 24v DC water pump to supply the house if needed.
Thanks, and yes, a small 12V RV style diaphragm pressure pump from a cistern would work fine in a pinch to get water to the home faucets and fixtures. My question, though, was about finding a good way to do the harder part--lift water out of me well and into the cistern using small diameter, low-flow DC pum120VAC pump.
 

Vigi

New Member
I would put your money and energy into buying an inverter that will run your current pump. The the inverter could also be used to power other things when not pumping.
Yes, I think that's where I may end up. And, it's not a bad answer at all--the cost difference isn't a lot between the 2000W (4000W surge) inverter I'd need for the pump and a more modest inverter I'd otherwise get. ( If I were buying a new main pump, maybe I'd get a Grundfoss pump to reduce the need for a big inverter.) On the other hand, having a small direct DC pump would be a lot more electrically efficient than converting to AC, and an independent pump provides a backup to the failure of the 120VAC well pump.

There are >so< many types of pumps on the market, it's hard to believe that robust and affordable 12VDC 2" diameter submersible pump that can handle a 50PSI head pressure isn't available.
 

time2roll

Photon Sorcerer
1/2 HP 70 feet down on 12 volt wire may not be practical. Too many amps. OK maybe a bit more efficient but still a long wire.

Yes I would have a 2000 watt sine inverter driven by a DIY 24v LFP battery. Connect a sub panel to a transfer switch and move a few lights, fridge, maybe the furnace blower if it runs on 120v, and one branch of outlets. You could use manual power management or go 3000 watts. Still need to be watchful on what is running. Then just to calculate run time needed. Possibly a small generator to charge the battery or some solar in the future.

I have a 1000 watt inverter that just starts a 1/2 HP pump (810w running) for if my in-ground sump quits or the power is off. This to clear some water out of a low driveway.

I was thinking 2000+ gallon water storage to last a few days or a week. May not be practical to have this monster sitting around all year just in case.
 

Vigi

New Member
1/2 HP 70 feet down on 12 volt wire may not be practical. Too many amps. OK maybe a bit more efficient but still a long wire.
I was aiming for a much smaller pump for this backup system. My "regular use" 1/2 hp 120vac pump (approx 800 running watts) produces about 8 gpm. For this backup pump, I'd be very satisfied with 1 gpm, and even much less than that could be a lot better than nothing. 4 hours of sun = 240 minutes. In a bad situation,, 240 gallons of water per day would be very welcome.
So, if 1gpm could be pumped with 100 watts (same efficiency as a none-too-efficient AC pump), then the 12vdc pump would require about 8 amps. If we just need 100 feet of cable to the pump, 12awg wire should be okay for that (approx 10% losses, not a dealbreaker in this application). At today's prices, I'd probably favor getting an additional panel if needed rather than go with bigger cable (another panel gives more flexibility and redundancy).
 
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