Gardena 4000/4 LCD Pump controler replacement

Hi Guys,
My family has a well in the garden. We use it to water the plants. We have the above mentioned pump and it has served us fine, but now there is a problem with the controler. If you stop watering for a few seconds, the pump turns of, to not waste energie, so far so good. But if you want to start watering again, it doesnt start pumping. I assume, the sensor which measures flow rate and pressure is broken. I can get a replacement, but it would be really expensive, so I thouhgt of building a "controler" myself using a relais, an arduino nano and a water pressure sensor. The idea is: turn the pump on, if pressure is below a certain value, turn pump off, if pressure is above a different value. Any thoughts on that?
The pump uses 850W max. I ordered a relais board from amazon, which is rated for 250V 10A, which should be sufficient.
Did I forget anything?
Greetings from germay,

Nice idea, but trying to design something based on an assumption may mean your water supply will not work for several years.

Either I try ro repair this pump, or my Patents buy a New one. I just font like the idea of throwing this pump away if just one sensor is broken

Hi @devryd ,
I imagine it works that way;
You turn on the pump, it starts to rotate and waits for pressure.
If the pressure is too low, it means lack of water in the well.
If the pressure is too high, the water outlet is closed.
So there is a pressure range where there is water in the well and the outlet is closed, the pump must not work.
And if there is water in the well and the outlet is open and the pump has to work.
And if there is no water in the well, the pump must not work.

RV mineirin

No water in the well is not a thing here. We have a seperate pump, that turns on when the water level is to high and pumps it to the sewerage

Have you examined the pump and it's controller?
Please keep us posted on your progress.

Good luck...........

is the controller integrated into the pump or has the controller an extra-housing?
850W means it is a 230V pump. If this pump has no plug like this


This would mean you have to mess around with wires that use 230V.
This is only allowed for well trained experts with a formal examination.

Without a final expert-check of a person who has all the equipment and the formal graduiation to do so you should not repair this pump.

Additionally it is with water because it is a water-pump.

Imagine: how much money would you pay each month for the rest of your life if paying this money would bring back a person to life that you love ?

If you find a already certified 230V-switch with a 230V-socket which can be used outside and is rain-protected (IP44) and has a 5V input and your pump has a 230V-plug like in the picture above you are on the secure site.

Not that cheap but safe to use

best regards Stefan

My father is a trained electrician, even if he isnt working in that field anymore. He still is allowed to work on 230V, so I should be fine. I'll just ask him to do it with me. I know 230V can be dangerous, thanks for the warning, though. I will put the controller in a water tight box, and I will make sure, that the connectors for the motor will be sealed as well.

I will keep you posted, but it might take a few days, since I dont have the water pressure sensor yet

Everything worked out fine. The motor is connected with 2 wires. Its a capacitor motor, directly powerd through 230V with a relais. I took the old controller out and put in an arduino with a relais board that turns on the relais, if the pressure is under 3 bar and turns of the relais, if the pressure is over 5 bar. It works fine and is (as far as I can tell) as water proof as the other controller was

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@ devryd,
Thanks for the update.