Need ideas on cistern pump with 12v solar system

solarpowernovicesolarpowernovice Solar Expert Posts: 129 ✭✭
I have a cistern about 75 feet uphill (not very steep) from my off-grid cabin and I need to find the best way to get water out of it into my cabin. The water will only be used for showers/toilet/washing dishes and not to drink. Would pumping the water out with a hand pump into a barrel down the hill beside the cabin then have a 12 volt pump on the barrel to pump the water inside work? I'd like to bypass the 1500 watt inverter so I wont have to unplug my chestfreezer to fridge conversion to use the pump.

Comments

  • jcheiljcheil Solar Expert Posts: 722 ✭✭✭
    Re: Need ideas on cistern pump with 12v solar system

    You could get by with gravity feed if the water level is not too deep and you could bury a pipe below the water level.
    You get 1psi for every 2.31 feet in elevation, so at 75' you could get 33psi which is more than enough.
    Heck, if you have a good flow rate you might even be able to set up a mini hydro!
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • Texas WellmanTexas Wellman Solar Expert Posts: 153 ✭✭
    Re: Need ideas on cistern pump with 12v solar system

    You need about 30 psi to go 75 feet up and still have water flowing at the top. I see a lot of posters use and recommend the shur-flo 12V pumps. Mount the pump so it pulls directly from the cistern and install a ~20 gallon pressure tank.

    On reading the 1st reply I realize you're going downhill, not up. Even better.
  • solarpowernovicesolarpowernovice Solar Expert Posts: 129 ✭✭
    Re: Need ideas on cistern pump with 12v solar system

    how thick would the wire have to be from the batteries to the pump 75 feet away? to JCHEIL: the cistern is underground and is i think 5 feet deep.. and the incline up hill to the cistern is a very low incline
  • jcheiljcheil Solar Expert Posts: 722 ✭✭✭
    Re: Need ideas on cistern pump with 12v solar system
    how thick would the wire have to be from the batteries to the pump 75 feet away?

    Are you unable to consider the gravity feed approach? Then you would not need a pump at all.

    In order to determine the wire size we would need to know how many amps the pump will draw at the end of that 75' wire. And we are still talking a 12v pump right?
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • solarpowernovicesolarpowernovice Solar Expert Posts: 129 ✭✭
    Re: Need ideas on cistern pump with 12v solar system

    I dont know how the gravity feed thing would work... I'd have to bury a pipe connected to the bottom of the cistern all the way to the cabin correct? I think the bottom of the cistern is about the same level as the cabin, and yes id like to use a 12 volt pump if possible to avoid having to buy another inverter. Is the hand pump to a holding tank* beside the cabin not a good idea? this would give me the ability to pump water out of the cistern even if my solar system was down for some reason.
  • jcheiljcheil Solar Expert Posts: 722 ✭✭✭
    Re: Need ideas on cistern pump with 12v solar system
    I dont know how the gravity feed thing would work... I'd have to bury a pipe connected to the bottom of the cistern all the way to the cabin correct? I think the bottom of the cistern is about the same level as the cabin, and yes id like to use a 12 volt pump if possible to avoid having to buy another inverter.

    ok, in that case you are right it would not work. I was under the impression the water level in the cistern was 75' higher than the cabin being up on a hill. So yeah you are back to a pump option. So how far DOWN is the water in the cistern from the LAND at the top of the hill, because you can only "suck" water to about 25' "up".
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • solarpowernovicesolarpowernovice Solar Expert Posts: 129 ✭✭
    Re: Need ideas on cistern pump with 12v solar system

    the cistern is 5 feet deep and the top of the cistern is all you can see its basically level with the ground, it just sticks up a little. then from the cistern to the cabin is 75 feet down a very low slope. I wish i had a picture to show you lol
  • jcheiljcheil Solar Expert Posts: 722 ✭✭✭
    Re: Need ideas on cistern pump with 12v solar system
    the cistern is 5 feet deep and the top of the cistern is all you can see its basically level with the ground, it just sticks up a little. then from the cistern to the cabin is 75 feet down a very low slope. I wish i had a picture to show you lol

    OK, so the TOP OF THE HILL is not 75' higher than the cabin, the top of the hill is 75' AWAY from the cabin...?
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • solarpowernovicesolarpowernovice Solar Expert Posts: 129 ✭✭
    Re: Need ideas on cistern pump with 12v solar system

    Attachment not found.yes sir that is correct here im drawing a little picture of how it looks :)
  • vtmapsvtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    Re: Need ideas on cistern pump with 12v solar system
    jcheil wrote: »
    In order to determine the wire size we would need to know how many amps the pump will draw at the end of that 75' wire. And we are still talking a 12v pump right?

    Those 12 volt 2088 series shurflo pumps draw about 5-6 amps.
    For example: 75 ft of #6 cable carrying 5 amps will have a voltage drop of 0.3 volts. I wouldn't go much thinner on the cable... the lower the voltage goes, the more amps the pump wants to draw. That lowers the voltage even more. Those pumps are not rated for continuous duty and they can be damaged by overheating. Especially when the voltage is low.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • ramlouiramloui Solar Expert Posts: 106 ✭✭
    Re: Need ideas on cistern pump with 12v solar system

    Just so it is clear, what is the relative difference in height between the level of the water in the cistern and the faucets? Whether the supply pipe goes up and down between the tank and the user is irrelevant (except for friction losses). For every foot of water elevation difference you have 0.45 psig static pressure available to you. My uncle had a cabin that was supplied with a water tank that was up a hill about 60-70 ft relative elevation. No pump. Very good pressure at the cabin.

    My setup is very similar to what you are describing. I pump water from the lake to a 250G tank on a 20 ft hill. Then the water flows by gravity to 2 12V pumps in my shed where all my electrical system is. The pumps then pressurize the water supply line to the cabin through a 20G bladder tank. This tank makes it possible for the pumps to not cycle on and off every time I open a faucet. It works very well for me.
    Off-grid cabin in northern Quebec: 6 x 250 W Conergy panels, FM80, 4 x 6V CR430 in series (24V nominal), Magnum MS4024-PAE
  • solarpowernovicesolarpowernovice Solar Expert Posts: 129 ✭✭
    Re: Need ideas on cistern pump with 12v solar system

    Ok so it lookls like #6 gauge and a shurflow is the best bet then.. this way I dont have to get a bigger inverter than the 1500 watt I plan on buying and already have 2/0 cables for..

    EDIT: or would it be better to pump the water down to a holding tank like ramloui said? is there a hand pump that can do this so i can always get water out of my cistern even without power? This way I'd only have to go out and hand pump once a month or so just to fill the holding tank up... then from the holding tank to inside the cabin with a 12 volt pump?? what do you guys think is the best idea?
  • ramlouiramloui Solar Expert Posts: 106 ✭✭
    Re: Need ideas on cistern pump with 12v solar system

    Unless it is physically impossible, there is no need to put the pumps near the tank. You could very well run the pipe from the cistern to the cabin or where you electrical supply is, put the pumps there and then feed the cabin.
    Off-grid cabin in northern Quebec: 6 x 250 W Conergy panels, FM80, 4 x 6V CR430 in series (24V nominal), Magnum MS4024-PAE
  • vtmapsvtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    Re: Need ideas on cistern pump with 12v solar system
    what do you guys think is the best idea?

    In favor of having a holding tank and a pump at the house: much better situation with lightning. When lightning strikes in your neighborhood, the ground at your house and the ground at the cistern can be thousands of volts apart... and you have been kind enough to make a 75 ft copper path between the two!

    Regarding your other questions... Do you have freezing temperatures to contend with? Were you planning to bury the line between the house and the cistern?

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • jcheiljcheil Solar Expert Posts: 722 ✭✭✭
    Re: Need ideas on cistern pump with 12v solar system
    Ok so it lookls like #6 gauge and a shurflow is the best bet then.. this way I dont have to get a bigger inverter than the 1500 watt I plan on buying and already have 2/0 cables for..

    EDIT: or would it be better to pump the water down to a holding tank like ramloui said? is there a hand pump that can do this so i can always get water out of my cistern even without power? This way I'd only have to go out and hand pump once a month or so just to fill the holding tank up... then from the holding tank to inside the cabin with a 12 volt pump?? what do you guys think is the best idea?

    Well if you didn't have power, then even if you had water in a holding tank at the cabin you would not be able to use it (if it was at ground level). So a hand pump would likely not help anything along those lines. I personally like the holding tank idea. I have one, 275g, up on a 14' tower, and fill it with my well pump usually once a week. Even without power, I can still get about 8psi which is enough to do everything I need to (although I do have a sureflo inline to give it extra pressure if I needed to). So if I were in your situation, I think I would do the same thing I have, an elevated holding tank at the cabin that gets filled from the cistern once a week.

    And that being said, I would just get a cheap 110v higher volume cheap pump ($120 www.harborfreight.com/1-horsepower-shallow-well-pump-with-stainless-steel-housing-69302.html) that could pull from the cistern to fill the tank. Since you would only have to fill it once a week, you could still use your inverter (just turn everything off while filling once a week) and not have to run wires up to the cistern since the pump could be at the cabin. And if you wanted that extra pressure, just add the 12v sureflow from the holding tank to the cabin.
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • solarpowernovicesolarpowernovice Solar Expert Posts: 129 ✭✭
    Re: Need ideas on cistern pump with 12v solar system

    thank you all for your great ideas I really appreciate it.
  • solarpowernovicesolarpowernovice Solar Expert Posts: 129 ✭✭
    Re: Need ideas on cistern pump with 12v solar system

    I do have freezing temperatures to contend with but its just a seasonal cabin right now I dont use it in the winter, but I will be using it in the winter some day. I think the holding tank is the best idea too.. are you sure a 1500 watt inverter can run a 1hp shallow well pump though?
  • jcheiljcheil Solar Expert Posts: 722 ✭✭✭
    Re: Need ideas on cistern pump with 12v solar system
    I do have freezing temperatures to contend with but its just a seasonal cabin right now I dont use it in the winter, but I will be using it in the winter some day.

    ...then the storage tank would be an issue unless you put it inside and insulated it very well. Then you would HAVE to use the sureflow to provide pressure to the cabin. But I would still go with the inside storage tank idea (perhaps a basement or bury it deep enough below freezing depth).
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • mike95490mike95490 Solar Expert Posts: 9,459 ✭✭✭✭✭
    Re: Need ideas on cistern pump with 12v solar system

    I pump uphill from a pond, to elevated storage tanks. Then the elevated tanks provide pressure, and I only have to run the pump 1x a week in the winter for house water.
    Be sure to use large enough pipe - tube, to reduce friction losses. 75', I'd use 3/4" as the minimum. Poly pipe will handle being frozen and thawed. But critters can chew it if not burried. OK in sunlight for 5 years or more.
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  • solar_davesolar_dave Solar Expert Posts: 2,384 ✭✭✭✭
    Re: Need ideas on cistern pump with 12v solar system

    If there is enough "run" down hill to keep the 12 V pump flooded wouldn't something like this work OK. Seems much easier than a long 12 V run.
  • Texas WellmanTexas Wellman Solar Expert Posts: 153 ✭✭
    Re: Need ideas on cistern pump with 12v solar system

    Be wary when having long suction runs like that. It's OK on the pressure side of the pump but causes problems on the suction side if the pipe is too small.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Need ideas on cistern pump with 12v solar system

    As long as the bottom of the cistern is ABOVE the point of use the water will flow as stated previously. You can then use a pump in the cabin to increase pressure .

    You just need a laser type level or an old style construction level on a tripod to do you testing of relative heights.

    add: PS once the pipe is filled it will siphon replacement water, just so long as the pipe flows downhill.
     
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  • solar_davesolar_dave Solar Expert Posts: 2,384 ✭✭✭✭
    Re: Need ideas on cistern pump with 12v solar system
    Be wary when having long suction runs like that. It's OK on the pressure side of the pump but causes problems on the suction side if the pipe is too small.

    That is why I said the line size was a SWAG.
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