Advice on off grid water pump.

[pmeyers]

I currently have an off grid water pump system that works well. Grundfos 6SQF-2 Helical Rotor pump, and Grundfos SQFlex controller and system monitor. Getting approx 5 gallons/ minute at peak. Right now, I have to manually turn the pump on and turn it off. I need a means to control the pump when I am not at the property to make sure that my tank doesn't go dry or that I don't over flow the tank. The obvious answer is a float switch, which I have and could connect to the controller, but the distance to the tank is too far to trench for the line in a very rock soil and if I laid it above ground it would be eaten by rabbits. It was suggested to me that I could put in a timer relay that would give me the option of having the pump come on a fixed amount of time each day. I wonder if someone has done doing similar and could point me in the right direction for a wiring diagram and parts list? The pump is powered directly from the solar panels through the controller and is rated for 5-240 vdc. Any advice would be appreciated​

 

[Reach4]

Float-controlled valve at the tank, and a pressure switch and pressure tank at the pump?

 

[Sponsor]

 

[JoeJee]

You could run the wire (temporarily of course till you get a tractor to dig a trench) with a pvc sleeve on the ground or in the air. That would minimize any animal risks.

 

[Bannerman]

The float controlled valve R4 suggested, would work similar to a common fill valve in a toilet tank. Because that valve is mechanical, no wiring between the storage tank and pump controller would be needed. A pressure tank and electrical pressure switch would be located nearby to the pump.

If the fill valve flow rate is equal to or greater than the pump delivery flow rate, then the pump will not cycle while the storage tank is filling. If the float is adjustable so as to commence refilling the storage tank after a substantial volume of water has been consumed from the storage tank (ie: 30+ gallons), then a very small (4.5 gallon) pressure tank could be utilized as the larger volume to enter the storage tank will ensure the pump will operate for sufficient time to satisfy the usual 60-120 seconds minimum run time for the pump.

 

[Reach4]

An alternative to a float valve would be a solenoid valve controlled by a float switch. That has the advantage that you can control the deadband easier. The longer the tether on the float switch, the more deadband there is.

You don't want one cow drinking 1 gallon to make the pump turn on.

 

[VAWellDriller]

I've seen folks with these pumps just let the sun be their timer....sun shines, pump runs no sun, pump is off. The ones I've seen set up are generally so low flow that overflowing is not all that big of a problem. If you have lots of excess flow, maybe a dole valve on the output to get it to closer match your demand, or turning solar panels so they are not at optimum position??