getting basic control systems to communicate over distance.

[Gareth J]

The basic situation;

Two neighboring farms both with own water supply and storage. Occasionally water runs out at the higher demand site.

On those occasions, I'd like to, when the lower demand site storage is full, pump surplus up to the higher demand site.

The pipework to achieve this is more or less in place and we occasionally transfer water and regulate it manually.

I have, in my head, simple, analogue, ways to only pump water when the lower demand site is full and equally only receive water at the higher demand site when storage levels are dropping.

However, I need to be able to communicate the "I'm full" signal (ultimately it'd probably be used to just open an electronic solenoid valve) from one site to the other. Which is some distance.

Laying a cable to do it's not feasible so it would have to be something done through the airwaves.

Any ideas for simple or clever options? Both sites have 240v electric available but not easily available WiFi.

 

[ajlelectronics]

Point to point link from Ubiquiti will do that. In effect it will give you an internet service at the remote end. You need good line of sight though. PtP links are much lower cost than they used to be. I have bought one that does up to 18 miles for £350 complete.

 

[ajlelectronics]

If you had internet one end, then a Point to point link from Ubiquiti will do that. In effect it will give you an internet service at the remote end. You need good line of sight though. PtP links are much lower cost than they used to be. I have bought one that does up to 18 miles for £350 complete.

Otherwise, if you have no service whatever and can't get one, then perhaps a pair of 4GEE routers on a low tarrif would do that. The routers are free if you have 18 month contracts, else £99 each.

 

[Ton-up]

What type of storage are you using, a tank? Cant you just use a pair of float valves?

 

[ajlelectronics]

Another option would be a mobile phone switch. You have a receiver that responds to an incoming call in what ever way you wish. However, you would need to find a way to make a 'phone initiate a call on demand. A bit of a cobble really.

 

[angellonewolf]

What type of storage are you using, a tank? Cant you just use a pair of float valves?

^^^^^my first thought but as the motor will not not stop pumping i think is the problem here but is there not a mechanical pressure switch that would turn off the pump in event of no flow ?

 

[daleyd]

I think it was @Burdekin (Could be wrong) that had a heater in his workshop that could be controlled remotely? Might be worth a search for the thread...

 

[Ton-up]

You use a pump with a pressure control on it, google Presscontrol.

We use these to keep tanks full on boiler systems as we have low mains pressure. The pump keeps pressure in the system, we have expansion vessel in line too to give a buffer. As soon as one of the float valves open, the pressure drops and the pump comes on. When the float valve closes the pressure rises and the pump turns off.
They seem reliable, I changed one 3 months ago, and they have been in for 11 years!

 

[daleyd]

http://www.mig-welding.co.uk/forum/threads/remote-switching-via-a-text-message.78650/#post-1102487

Here is the thread, but it was using a text message to control. If you wifi access I imagine it would simplify things a lot.

 

[Sputter]

I'm a bit of a pessimist when it comes to control systems, so I would be wary of a wireless system that only sent an "I'm full" signal. If for any reason the signal got lost, you will end up with a flood. It would be more fail safe if the demand end kept sending out a "Fill me up" signal and the pumping end stopped if this went quiet.

Alternatively, I wonder if the water pipe itself could be used to do the communicating ? At the high use site, fit a solenoid operated valve and energise the solenoid only when it needs filling.

At the other site, put a non return valve in the pipe and fit a pressure switch. Possibly a bladder expansion tank too to help keep the pressure high when no water is being drawn off. Then just wire the pump to only turn on if the pressure is low and the water level is ok ?

Edit : ton-up was saying much the same thing as I was typing !

 

[rtbcomp]

Solenoid valve opens at the upper tank when level drops.

Pump at lower site is controlled by a float AND a pressure switch, starts when (lower water level is high enough) AND (no pressure in pipe) i.e. solenoid at upper site is open.

You would need a non-return valve at the lower site between the pump and the pressure switch, and perhaps an air resevoir to hold the pressure for the switch.

 

[Gareth J]

Thanks for all the replies! There is no line of sight, I could get WiFi to the low usage site ok.

What type of storage are you using, a tank? Cant you just use a pair of float valves?

One (low usage and lower altitude) site uses underground rings pre filtration. The other uses underground rings plus above ground tanks post filter but pre booster pump. I want to top up these above ground tanks with potable water from the low site.

^^^^^my first thought but as the motor will not not stop pumping i think is the problem here but is there not a mechanical pressure switch that would turn off the pump in event of no flow ?

I can simply stop the flow into the storage tanks once they're full, that's simple. What I can't do only let water flow over if storage at the low site is getting full.

I'm a bit of a pessimist when it comes to control systems, so I would be wary of a wireless system that only sent an "I'm full" signal. If for any reason the signal got lost, you will end up with a flood. It would be more fail safe if the demand end kept sending out a "Fill me up" signal and the pumping end stopped if this went quiet.

Alternatively, I wonder if the water pipe itself could be used to do the communicating ? At the high use site, fit a solenoid operated valve and energise the solenoid only when it needs filling.

At the other site, put a non return valve in the pipe and fit a pressure switch. Possibly a bladder expansion tank too to help keep the pressure high when no water is being drawn off. Then just wire the pump to only turn on if the pressure is low and the water level is ok ?

Edit : ton-up was saying much the same thing as I was typing !

Complications include water troughs on route between sites that need to be constantly pressurised. Any on/off control needs to be at the high site end.

...

If it's not really feasible, a simple experiment that would be much easier than me manually regulating would be to just plumb it in permanently but so that it only transfers across when the storage tanks are getting low. Yes, I might run out of water at both sites but if things are that bad, I'll be using mains water either way.

 

[Matrixx]

the cheapest option would be using mobile phone technology to send signals ( like gate openers), you would need some automation to control the pumps and open valves so I would use a PLC (programmable logic controller) connected to a mobile device, you would need a PLC at each end to monitor pressure tank levels and valve positions, even flow rates if required, but if you could run a cable then fibre optic would be the first choice.
but either way its going to be at least a few hundred to buy all the bits

 

[rtbcomp]

Where does the water come from initially?

 

[Gareth J]

Where does the water come from initially?

The ground. Two wells. It's groundwater but its availability is heavily related to rainfall.

There's also a borehole. But it's also not that reliable a supply and despite us trying a couple, the borehole quality is terrible.

 

[rtbcomp]

I was thinking in terms of just starting the pump at the low demand site when there was sufficient water in it, and if the high demand site over-fills then so be it. The pump could be on a segmented 24 hour plug-in timer set to, say, 15 mins on 15 mins off (as well as a float switch) to regulate the amount of water pumped.

 

[Maker]

Complications include water troughs on route between sites that need to be constantly pressurised. Any on/off control needs to be at the high site end.

How do the troughs work that they don't need to send signals? Could the tank be set up to fill in the same way the troughs do?

 

[dannyp]

I’m sure this chould be done with simple logic and no communication well very littel

 

[Gareth J]

I've resigned myself to accept that I'm not going to be able to design a setup that will achieve exactly what I want it to. I'm wary about spending ages trying to create a box (or two) of tricks of unknown reliability that can't be fixed quickly/easily.

I think I'm better off at least test driving a permanent connection that kicks in to boost the high site tanks when they're low regardless of the status of the low site's storage.

How do the troughs work that they don't need to send signals? Could the tank be set up to fill in the same way the troughs do?

Ball valves on a constantly pressurised line. It's how I would fill the tanks in the above scenario. There's no communication as such

 

[WorkshopChris]

I think I'm better off at least test driving a permanent connection that kicks in to boost the high site tanks when they're low regardless of the status of the low site's storage.

If you have water at the high site and are running low at the low site do you have to pump or will gravity let you return water.