Cistern to Gravity feed tanks in Mexico

[Seaweeds]

Hello. I am putting together a simple little system in my Mexico place that is different enough that I thought to check with some pros.

First of all, the system has consisted of two storage tanks at the top of the hill fed by the town water, which in Mexico is "liberated" on a schedule. They open a valve and send water down our branch once a week and I used to capture maybe 2500 liters. These tanks gravity feed two houses. We are fine with the gravity pressure, don't need anything there. But due to recent changes, I'm now having trouble receiving any water at the top of the hill where my storage tanks are so I'm going to install a cistern at the bottom of the property - about 15 meters down from the top. This should make a difference.

So, it will work more like a rainwater collection system than one with a well.

The upper tanks will almost always be partially empty, rarely topped off for long. They are plumbed into a T but I keep one feed closed so that if one tank drains out there is still another in reserve.
The Cistern will only see water coming into it once a week. It will pump that tankful to the upper tanks for usage over the week. Typically the float switch in the cistern will shut off the pump as it finishes off the tank. On rare occasions, the upper tanks may fill completely before the lower tank is empty. In that case I need to shut off the pump based on the fill level of the upper tanks. Right now they have mechanical float valves that shut off flow like a toilet when full.

The typical pump in these systems is what they call a "Periferico" not sure if that's a jet pump? But it's a high lift low flow exterior mounted pump. I need to lift 2500 liters about 15 meters over a 100 meter run and the 1/2 hp linked seems like it can handle that easily. I don't really care about flow rate as long as it does that. The good one linked costs about $45. I'm fairly convinced that I don't need the cost of a submersible but maybe somebody has a good reason.

My question is really about the control - isn't it always?

I've read several threads here and saw that besides the float switches everyone here uses there is another method with a pressure tank.

So, first question is whether I should be considering a pressure switch to shut off the pump.
Is it as reliable as a relay and float switch?
Seems I read that it must be a pressure tank with a switch, not just a switch, correct? This won't work alone?
Will the pressure tank in-line lift the water just like the pump alone ?
Can I use one of these smaller cheaper pressure tanks with a pressure switch to shut off the pump when the upper tanks fill and their valves close? does tank size matter at all?

Or does it require the full size tanks?

The upper float switch option:
With a 100 meter run to the top, it seems like wiring float switches will be slightly simpler but then I have to choose the voltage (110AC or 24vac?) and the wire to run it and then a relay.
If nobody said otherwise, I'd forget the pressure tank idea and just buy some 16 or 18 ga speaker wire and run 110 AC up and back to manage a relay. It prices out better than ethernet cable for me.

My power quality is poor (I'm not just short on water! ) and already has plenty voltage drop when the fridge turns on so I don't think it's wise to power the pump directly through the upper float switches. If I did, I'm fairly certain that the wire gauge/cost would have to increase quite a bit.

For that reason and with the idea to isolate the pump from that long lightning rod, it seems to make sense to use a relay if switching 100 meters away.

So, for a float switched approach:
110 or 24VAC? or...
18 ga good enough, right?
Put a low amp (3 amps ?) fuse inline on the switch run? In case of a short along the way?

Thanks in advance, eh? I tried to read all related threads first but still would appreciate your opinions.

 

[Valveman]

Sorry. Still don't understand what you are doing? A pump with a pressure tank/pressure switch is needed to deliver pressure when there is no gravity to work with. With elevated tanks using gravity, you don't need a pump, pressure tank/pressure switch. Maybe a sketch of how it is set up?

 

[Sponsor]

 

[Seaweeds]

Sorry. Still don't understand what you are doing? A pump with a pressure tank/pressure switch is needed to deliver pressure when there is no gravity to work with. With elevated tanks using gravity, you don't need a pump, pressure tank/pressure switch. Maybe a sketch of how it is set up?

Sorry - I complicated my explanation with too much info.

Put simply, I need to pump from a cistern below to some tanks 50 feet above. I will shut off the pump with a float switch in the cistern when low. For shutting off when the upper tank is full, I will probably do the usual and go with a float switch there as well. I believe that a relay is best in that case as I can't afford any voltage drop.

So, apart from any advice otherwise, I'm just asking if 110 or 24 vac is best for that 330 foot run. And if 18 or 16 ga speaker wire with an inline fuse seems ok. with one or both voltages.

BUT I was intrigued by your suggestion in other threads to consider a pressure switch down at the pump instead of a wired relay when they are far apart. In that case, I'm asking if a pressure tank is absolutely needed in order to use a pressure switch and if the tank affects the lift from the pump. That's the only reason a tank is mentioned - in order to use a pressure switch.

I'll inflict my terrible sketching skills on ya if still needed just say so!

Thanks mucho.

 

[Valveman]

If you are using a float switch, you don't need a pressure tank or pressure switch. But with a pressure switch/pressure tank you don't need wires running to the cistern as you can use a non-modulating float valve or a solenoid valve controlled by a float switch.

16-18 is large enough for control wire, but the long distance may cause impedance and not let the circuit open. I use DC voltage when going a long distance with control wire.

 

[Seaweeds]

Thank you. I saw that discussion on voltage and AC vs DC. I guess I'll try the 110 first and go over to a power supply if needed. I saw a relay that will work at various voltages depending on the tap used.

Sounds like wiring a switch makes more sense to you as well.

Out of pure curiosity, am I correct in understanding that a pressure switch cannot be used without a pressure tank? I can't just plumb the switch into the line and have it shut off the pump when upper float valve closes and pressure rises?

One more question - As far as additional safety on running the pump dry or too long, I'm ignorant of the cycle valves or sensors and wonder if that helps or applies in my case.

 

[Valveman]

No, you do not want to use a pressure switch without at least a small pressure tank. Even then the output of the pump needs to be enough to keep the pump from cycling on/off while the cistern is filling.

A Cycle Sensor is what you need to shut the pump off when it runs dry. The Cycle Sensor can be wired with a pressure switch or a float switch.

 

[Seaweeds]

One more question. I settled on a submersible pump- "Kanki" style they call it here. Pump manual (pdf) The submersibles that are short and squat.
So it should already have a check valve in it. But since before I had been planning to use an external pump, I already ordered a nice brass Amerian check valve.

Now, I read the advice to only have one valve in the system at or in the pump. So, I could go ahead and install this check valve right above the pump for redundancy and added friction or I can sell it. Advice?

 

[Reach4]

That pump is meant to raise water about 5 meters mostly. The L/h numbers may be at zero lift. I am not sure.

I suspect "Altura máxima" is the amount of lift you can do at zero GPM or L/h.

 

[Bannerman]

I suspect "Altura máxima" is the amount of lift you can do at zero GPM or L/h.

The English manual is also included within the PDF.

 

[Reach4]

The English manual is also included within the PDF.

I came up with https://www.truper.com/admin/descargables/manual/15003.pdf (no English) but I probably should have kept looking.

 

[Seaweeds]

That pump is meant to raise water about 5 meters mostly. The L/h numbers may be at zero lift. I am not sure.

I suspect "Altura máxima" is the amount of lift you can do at zero GPM or L/h.

You might be misreading the specs. There is an English section starting page 13 if interested. The size I ordered (3/4 hp) has a maximum DEPTH of 5 meters, which would be the max water pressure it's seals can handle, I suppose. Designed for cisterns or perhaps very shallow wells, not deep wells. Max LIFT (probably Total Head) is 26 meters. It should work fine for my application. My head is around 11 meters and with Friction loss my total head should work out around 18 meters, keeping me near the middle of it's curve.

Just trying to decide if I install my non-returnable check at the pump, or try to sell it.

 

[Reach4]

Just trying to decide if I install my non-returnable check at the pump, or try to sell it.

A second check valve above the pump would not hurt and would offer some redundancy.