Irrigation of the lawn - cooperation of the rainwater tank with the water supply system

Hello, everybody!
I apologise at the outset if this is not the category. However, I know you know your stuff


I am doing irrigation for the garden. I would like the default to use rainwater from the tank (via a pump).
When the tank is emptied, the feed water would flow from the mains water supply. I thought of two solenoid valves.
1 - from the water mains
2 - from the tank (via a garden pump).
There would be some water level sensors in the tank
A) tank full - electro-valve 1 closed, electro-valve 2 open
B) tank empty - electro-valve 1 open, electro-valve 2 closed.
The pump would only start when there is water in the tank, and its activation and deactivation would be managed by the irrigation controller (rainBird RZX4) as of course the other irrigation sections. Please find attached drawings.
How do I do this? Is this even possible? If so, please explain in "simple terms" the connections and the things I need to use.
Best regards and best wishes.
Ps. What is that under "3" in the picture below?

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Hello .
You can use a CP-2 liquid level sensor.
Powered 230V , relay output without voltage , changeover contacts.
For this, depending on the load (especially), the pump should be used an additional stronger relay, or a small contactor (for example DILEM -10).
The relay output is not very powerful (relay up to 1A).
You use three measuring probes SO-common to the levels.S1 minimum,S2 max.
This is what it looks like Link

Thank you for your reply. And how do you control solenoid valves 1 and 2? Can you draw the connection of everything on a piece of paper and paste it into the topic?

You supply the sensor to terminals 4-(L) , 5-(N)
-from terminal (4) you make a bridge with a wire to terminal (8)
connect additional relays (their coils) to terminals (9)(10), the relays will control the solenoid valves and the modular contactor that runs the pump.
Tomorrow I will draw you a sketch of how this should look.

In your situation, one solenoid valve for filling the tank is sufficient.
When the tank is full, the pump relay will allow the pump to be started by your controller at the appropriate time of day. When the tank is empty, even if the controller allows the pump to be started (current watering time), the pump will not start anyway until the tank is full.
Relays of any 230V type R2M, R15 etc
Through the contacts of both relays P1 you will supply the phase (you did not write what voltage the solenoid valves are for), under the output of the relay contacts connect the solenoid valve.
Connect the operating contacts in series with the coil supply wire of the pump module contactor.You can use three or two courts for the tank.When there are two, S1 and S2 are connected together and it will be a full tank probe.

Thank you for your help. My colleague EL-Szwed suggested a different and cheaper solution.
I am adding a drawing if anyone else is interested in the subject.
Greetings!

It may be so, but it all depends what kind of float you are going to use because of the voltage of 230V you are going to apply to it.Additionally, it should have a PE wire.My solution is safe because there is no such voltage there.Maybe if you specify the kind of float you are going to use, it will dispel my doubts about such a solution.Using a float from a submersible pump is unlikely to work.

nikusert wrote:

Maybe if you state the type of float you intend to use , it will dispel my doubts about such a solution.

For safety reasons, I would rather see a hydrostat (from a washing machine or dishwasher) or maybe even two here. The biggest problem, however, would be protecting the whole thing from the weather and/or users.
Because the technical solution to such an issue is as simple as a stick of hazelnut. The problem, however, is safety. How about using a reduced voltage of 12 or 24 volts for the control and automation system? It would then be easier to enclose the actuators (relays or contactors) in some kind of sealed box.

nikusert wrote:

Additionally, it should have a PE cable.

Float switches generally do not have a PE cable.

retrofood wrote:

For safety reasons I would rather see a hydrostat (from a washing machine or dishwasher) or maybe even two.

Unnecessary complication of the design.
Let's not knock down an open door gentlemen.
Just use the simplest float switch, not a combination.
https://sklep-hydros.pl/sterowniki-zabezpiecz...wnik-05m-20m-plywak-do-pomp-zatapialnych.html
I use similar floats to control pumps in sewage pumping stations and they work faultlessly for years.

This is exactly what the float is about. The switchboard with fittings will be installed in the basement together with the controller, cables buried in the ground. All connections will be made in waterproof boxes, safety being paramount. To control the water from the water supply I will use a 24V valve such as for sprinklers with a trasformer. A garden pump will be used (I will mount it in the valve box so there is access).

I have not tested this type of float, hence my concern as to its operating range. Will such a float have the operating range you expect (won't it overshoot the minimum level and undershoot the maximum level).The other thing, if you are going to use a 24V solenoid valve, I would of course power the float with the same voltage, which is safe.

For those interested, the final version modified with a 24V (irrigation) valve and F&F 230V/24V AC TR-24 transformer



Operation:
Direct control via a float switch in the tank.
1. Tank full. Rain watering.
At a set time for a set period, the controller starts the pump opens the individual irrigation circuits. Water supply solenoid valve closed.

2. Tank empty. Watering with water from the water supply system.
The controller opens the water supply solenoid valve and the individual irrigation circuits at a set time for a set period. When watering is complete, the water supply solenoid valve is closed.
In this case, the pump is inactive.
After filling the tank with rainwater, see point 1 etc.
============================================
In connection with the "My Water" programme, I plan to add a second large tank to connect the other side of the roof and modify the installation additionally so that rainwater is also used if a tap is turned on outside.

Searching for the topic of water make-up control for a water tank I came across this one, so for the sake of completeness I'll just add: the above diagram is not compliant with the regulations. It is not allowed to connect the water supply system with the water supply system from another source (in this case, the rainwater tank) without separation by an air gap. There must be a non-pressurised connection between these sources (e.g. with a BA leakage valve of some kind). I am planning to top up the water at a low level in the rainwater storage tank directly into the rainwater storage tank when the water level in the tank is too low at a certain time before starting to water

Hi
i, too, want to solve this by topping up the rainwater tank - how did you manage this?

There is another important piece to this puzzle. You need to buy an irrigation controller that operates a relay. I have an RC2 Rainbird, which has an output to control the main valve/relay. I control the relay, which only supplies current to the submersible pump in the rainwater tank when irrigation is in progress. The submersible pumps when they have current all the time run every so often to maintain pressure and readiness. Which is unnecessary if the irrigation only runs, for example, every 2 days. I had one pump go out this way, so I learned from my mistakes.

Hi, I'm rehashing the topic as the next iteration of the My Water programme is starting in 2026 so it might be of use to someone, and I have a question for the author alchi8, namely what electro-valve he used, as according to his diagram after a voltage loss from the transformer it should change position to admit water from the water supply. I haven't seen that there are solenoid valves on the market that return to their position after a voltage loss, so I guess its return to the water supply has to be controlled by another relay and transformer....

I don't know if the author still remembers about this thread, but there are easily available solenoid valves that return to the "open" position after a voltage loss. I know because I have one myself, I was very surprised that it only has two wires and when 12V is applied it switches to "open" and when the voltage is removed it returns to the "closed" position. Of course, I wouldn't be myself if I didn't see how it's done, there's simply a supercapacitor in the housing that charges when the valve is open and powers the motor when the voltage is removed.
It looks more or less like this:

>>21844744 >>21844744 At his place there is probably an ordinary one, one from irrigation and it returns to the closed state after a power failure:


It's a pity they don't make 2-3 way ones for 12-24 VAC (I've only seen on DC)

stomat wrote:

I don't know if the author still remembers this thread

Hopefully the moderation remembers that posts older than twelve months are considered archived.
And the previous post #14 was written in 2022, another in 2024.
So another golden shovel goes to dzikson88.

zbich70 wrote:

Hopefully the moderation remembers that posts older than twelve months are considered archived.

There is an exception if a user has added advice to an old topic. Other than that apparently users look in and still have a problem. Don't be so harsh