looking for pump advice for cabin water system

thaddeusk

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Jun 7, 2021
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Hi, I am planning a power and water system for an off grid cabin. have about $5k to spend on everything (pump, pipe, wiring, battery bank, CC, inverter, BMS) and want to use the funds wisely. so, the plan is to pump water from the well (80 ft) which is located in a winter-shaded spot, up to a tank on a hill about 3-400' away, and gravity feed to the cabin which is in between the two. ideally the solar panels would go up on the hill as well as there is much better winter sun up there. question is, what pump setup would be best suited to this? total head from bottom of well to the tank will be about 150-180 ft, distance from panels to well about 3-400 ft. I don't see it as ideal to run DC that far for a dc pump. should I get a grundfos SQ and run it off the inverter? or just live with the low solar exposure at the well head and put dedicated panels closer to the well? 2-300 gallons per day would be more than enough, especially in winter. so I don't need a high volume pump. it's deep enough that I don't want to put in a cheapie and have to replace it frequently. if using an SQ, is the grundfos control box (another $400) required, or could I use something simpler to switch it off when the tank is full? just go manual control? it's possible that eventually it will get used to supply an automated irrigation system for a small garden in summer, but there's decent sun at the well in summer. Any thoughts are appreciated!
 

OzSolar

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Jan 5, 2021
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Hello,

It's hard to beat the Grundfos SQ. Great brand and very easy to run off of an inverter. I'm more familiar with the SQFlex and the SQE than I am the SQ but I don't think the SQ needs a control box (CU301?) other than the float switch feature. The SQE for sure needs the control box for the constant pressure function. That being said I'm unaware of any better way to than the controller and float switch to do what you want to do. Someone will correct me I'm sure!

How many feet above the cabin the storage tank?
 

Abodyofscience

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Feb 21, 2022
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With a 3/4 HP 30% efficient pump, at 6 GPM and 150' head, you get 60 PSI. But check the pump curve.
 

OzSolar

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Ideally aiming for 70-80 ft above the cabin for decent pressure there. Cabin is about 20 ft above the well head.
That should get all the pressure you need. Every 2.31 ft above the cabin gets you 1PSI in case you didn't know.

Just curious, why not a standard pressure tank in the cabin? There's likely a good reason but there's many factors I'm not aware of specific to your site. From what I'm reading it sounds like you are buying more pipe and doing a fair amount of civil work to get a gravity fed system that would be avoided if you just fed the cabin directly from the well. Just tying save you some money!
 
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thaddeusk

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Jun 7, 2021
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Just curious, why not a standard pressure tank in the cabin?
Having lived off grid with a number of different types of systems, I prefer to have a good supply of water - at pressure - that doesn’t require power to use. It’s worth it to me to spend a bit of extra money and work to get that peace of mind. and in a climate where a couple days without water could mean a totally dead garden, spending the money now could mean not having to spend it later on an expensive quick fix if something goes wrong with the well OR power system. Lastly, off grid on a small power system, a pressure tank means I need to be mindful of water use as it relates to power use in a way that a larger storage, gravity fed system doesn’t. With a pressure tank, two good showers can mean needing power for the pump right then. With gravity and storage, I could get a week of showers from one afternoon of sun.

most folks don’t think about how quickly their water runs out if their pressure tank well system has a problem. I’ve experienced it and don’t care to again.
 

OzSolar

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Having lived off grid with a number of different types of systems, I prefer to have a good supply of water - at pressure - that doesn’t require power to use. It’s worth it to me to spend a bit of extra money and work to get that peace of mind. and in a climate where a couple days without water could mean a totally dead garden, water runs out if their pressure tank well system has a problem.
I suspected you had some good reasons and those were all great.
 

Wellbuilt

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Sep 14, 2020
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I use the SQF pump
My pump is set at 700’ the SQF uses less power then the sq
I was going to run the pump on solar only
But it seams like a wast of solar power
I dropped the pump down with a 10/2 well cable with ground .
I just put a plug 🔌 on the end and plunged it into a regular outlet and up came the water @ 6 gallons a min .
I keep a 250 gallon water tank in my utility room and a second tank out side they both fill together .
I use a 110 rv pump with a regular presser tank this feeds 3 bathrooms Landry and kitchen sink .
The small pump uses 100watts of power
But I can do dishes and get a shower in just on water from the tank .
I power the pump from my inverter , I have a 20$ Mechanical timer that I can set to run for up to a hour .
My tanks are 525g and my pump can pump 360g max so it won’t over flow the tank
Pumping from a 80’ well is easy .
I think the setup is about 130lbs
You are not going to use much power 300watt or so I would just set up a regular tank and feed the cabin .
my moms well was put in I 1975 and the pump died a few years ago .
If you have to just keep the tank by the house and use a small pump .
I’m thinking about having 2 small pumps that way I get double the output and I have backup if one dies
 
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