Pressure Switch or Relay for Long Distance + High Head

chrisc
chrisc Registered Users Posts: 5 ✭
in Solar Water Pumping #1
Hi all,

Been lurking around for a bit. I love these forums and all of the cool projects people are doing.

I've been trying to figure out the best way to control the flow in a system with around 350' of head and around 1400' distance. This is for a off-grid cabin + garden which might use 50-100 gallons a day.

Right now I have a submersible and a booster that I run via a generator to push water up the hill. I am replacing this system with a Dankoff 1308 which I will put 40' down the well casing and which will be powered by 2 solar panels. (500w nominal, 24V.)

At the top of the hill is a 1500 Gallon tank. I'd like to stop the pump when it's full. From another thread I learned that a float valve combined with a pressure tank (to avoid chatter) and switch is the best way to deal with this.

So, my plan would be to.
1) Install a pressure switch at the well head.
2) Install the pressure tank near the tank, as I don't think I can get a pressure tank that can operate at the pressure necessary to push from the well head. Set to appropriate pressure.

A couple of questions:
1) Where can I get a reliable pressure switch that can handle the 130-150 psi necessary to send the water up the hill?
2) Is it better to run wire down the hill from a switch in the tank? If so, could you point me to a switch and such that will work over that distance?

Thanks,
Chris
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Comments

  • tmarch
    tmarch Solar Expert Posts: 143 ✭✭
    #2
    Re: Pressure Switch or Relay for Long Distance + High Head

    It would be simpler to just put a electronic float on the tank and run the wire from the controller to it.
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  • chrisc
    chrisc Registered Users Posts: 5 ✭
    #3
    Re: Pressure Switch or Relay for Long Distance + High Head
    tmarch wrote: »
    It would be simpler to just put a electronic float on the tank and run the wire from the controller to it.

    Thanks. Do you have a recommendation on the float, or should I just use the Dankoff one?

    -Chris
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  • Volvo Farmer
    Volvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    #4
    Re: Pressure Switch or Relay for Long Distance + High Head

    I use the Dankoff 11003 and am happy with it. You have a lot of wire to run there, but a float switch has got to be more reliable than a pressure switch in the long term.
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  • tmarch
    tmarch Solar Expert Posts: 143 ✭✭
    #5
    Re: Pressure Switch or Relay for Long Distance + High Head
    chrisc wrote: »
    Thanks. Do you have a recommendation on the float, or should I just use the Dankoff one?

    -Chris

    I don't use them, but the Dankoff should do fine.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #6
    Re: Pressure Switch or Relay for Long Distance + High Head

    I have run a float switch (in California, only non-mercury switches are allowed, 10 year lifetime for them) to control my pump. It's about 600' from the control head, up to the tank, so I used the switch to control a Contactor (heavy duty relay) that controls my pump.
    If you use a float switch, you don't want to use a pressure switch with it. A pressure switch has high hysteresis, and is made for use with a pressure tank [ 30- 60 psi range], not a bulk storage tank. And if you have a bulk storage tank up the hill, you should not use a pressure tank.
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  • chrisc
    chrisc Registered Users Posts: 5 ✭
    #7
    Re: Pressure Switch or Relay for Long Distance + High Head

    Thanks everyone for your great input, I've gone ahead and started stringing wire for the relay.
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