It seems as though you are leaning towards a fully automatic system so you need either a pair of level switches or level transmitter at the tank with either a wire to the pump shed or wireless system. If you are out in the country perhaps the wire could be something like a fence wire with ground return running at 24 VDC.

There are also lot's of wireless transmitters that would do the job but you would also need something smart at the pump end.

Another crude idea would be to have a level gauge on the tank you could see from the pump shed. You would look at the gauge then set the pump run-time on a simple timer.

 

Google is your friend

http://www.remotecontroltech.com/applications/pumpcontrol.aspx

 

Hi Mr.

I would suggest you to implement a floating type limit switch in your water tank that would be accessible from the top of the tank to solve this issue. I have personally experienced that problem and we have solved it with this simple instrument.

It has such a mechanism inside itself that when the water level rises and the instrument becomes vertical in the water, the control circuit mechanism inside the switch gives the open contact command to the pump so the pump stops and the tank doesn't over floats. When water level is lower than the desired level, then the switch becomes partly horizontal making the switch mechanism inside the instrument able to keep the pump working until it becomes vertical again. So in this case you will always have a water tank that is always full at all times and a one that would never float. The one that I have used was made in China. The vendor's name was Kripal.

Hope that helped.

 

Roy:

Thanks for the pointer to that web site with the prefab wireless control package. I never stumbled upon it during my Google searches. Although I am getting help from another member on a custom engineered alternative, your suggestion also looks very promising.

 

> I am currently pumping water up to atank that is about 700 meters from the pump shed.

---- snip ----

Try this. Let overflow to be guided to a mechanism that can cut off the the pump, by gravity of water being collected by the mechanism.

 

I think radio-control is a very simple way that may help you. You just need to use two I/O modules which can transmit the ON-OFF condition wirelessly.

For I/O modules, you can check here:
http://www.rf-data.com/product.asp?BigClassName=I/O+MODULES

 

So what solution did Desert Rancher settle on?

My guess is he hasn't done anything.

Roy

 

I note one comment about finding fittings or this tank and another about pump start stop cycling.

One added feature of the float valve approach is that a typical float valve in a toilet cistern tends to be maintained closed until the tank empties which it does rapidly so the float valve opens immediately and starts the refill process.
If the outflow doesn't empty the tank then there is a chance the float valve will drop a bit then trip the pump on and quickly top off the tank and close again. But what's the point of the tank then? You might just as well fit every outlet served by the tank with a float valve and the pump with a pressure switch and let it run when any valve opens.

With a tank you usually want to operate between a high and a low level point. The pump starts when the level reaches the bottom and stops when it reaches the top.

This can be achieved to a degree with special delayed action float valves.

For example, here: http://www.keraflo.co.uk/Home.aspx?PageID=1
A google for delayed action float valves should find plenty similar.
I think then that the float valve working with a pressure switch is a way forward.

Or maybe a flow switch if, when the float valve opens, some sort of flow will occur as per a power shower.

If the system can be adapted such that some trickle flow will initiate when the float valve opens, then this can bring in the pump and will get round the worries about pressure decline in the pipeline and false pump starts with a pressure switch.

 

Float switches, levels switches, radio transmitters etc all require power and/or a wire to the tank, which the OP specifically said he cant do. (Batteries go flat, solar cells are expensive)

That leaves only pressure sensing at the pump. And many of the suggested solutions about using standpipes etc are impractical, expensive (wanna instal another tank anyone) or unreliable.

I am also curious if/how this problem actually got solved.

 

You can put simple device that measures the conductivity at the top of your vessel. When water is there, the resistance will drop, so the pump will be switched on. Simple detector made by two metal bars situated on appropriate distance will fit.

 

We are working on such a kit. Our preliminary designs have proved to work at 1.5 miles away with line of site. The tank sensor is solar powered and works with simple but effective float switches (we have found these to be the most reliable). Feel free to visit our website or email us for more information. http://www.filltronics.com

<b>Moderator's Note:</b> As many of you know, your moderators usually don't post product information to old posts. I have made an exception in this case. Not because I know anyone at Filltronics, but because access to clean water or a method to filter drinking water is important in may parts of the world. People from all over the world read and post to the Control.com forum and some of them may find this useful.

 

I am the original poster and am grateful for all the suggestions, expert advice, and links to potentially useful sites. Phil Corso was especially kind in helping me develop through separate communications a pump control design using float switches and relays, tied together with a Smart Alarm proprietary device. I have yet to execute the design. There have been two obstacles that have kept me from moving forward. One is that I have been preoccupied with building a custom home on my little ranch that takes nearly all my time and money, so I've just lived with the existing manual system, which is a pain, but simply works. The other reason is that the design requires a long hard wire between the tank and the pump. In the harsh conditions of the desert southwest, where wind and heat can be ferocious, a good quality and expensive aerial cable would be required. There are existing power poles for part of the distance, but I need permission from the power company to hang a cable on their poles and I'd still have to trench in very rocky ground or install additional poles for that section where poles are not existing. So, a radio controlled system sounds appealing, but I haven't seen a simple and cheap radio system yet. Remember there is currently no power at the tank.

Thanks to all who have taken interest in my situation. Perhaps before too many more years go by, I will report on a successful installation.