• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Float valve circuit issue

Not open for further replies.


New Member
Hello guys,
I am looking for some advice on how to problem solve the current issues with the circuit I designed.

Create an timed automatic plant feeding system.

To fill and drain pots connected to a dummy pot. The water level to be controlled by float valves inside the dummy pot and feeding to be activated by a timer.

Timer switches on which activates the relay and sends power to pump A in tank which fills dummy pot with water until it reaches the level of the top valve which is NC. The water level rises until it opens the top valve which switches pump A off. Water stays in the pots until the timer switches off, cutting the power to the relay which cuts the power to pump A. The bottom valve which is NO is now closed due to water level, relay returns back to normal position and pump B which sits inside the dummy pot pumps the water back into the tank until the bottom valve becomes open and cuts the power to pump B. This cycle is repeated.

1) Relay buzzes / chatters
Relay is either flicking on and off or not flicking at all but an electric current can be seen jumping across the switch. Maybe the coil is received not enough voltage/current to keep the coil activated or it is receiving too much.

2) Both pumps stay on at the same time.
Circuit B which is constantly on due to the connection should not have any power when the relay switches to activate circuit A. Not sure why it is overpowering the relay. Maybe voltage is too high in live in or too low in live out.

Tried = Changing the brand of relay, Changing the voltage of relay. 240vac and 230vac as using power from mains. What did work was disconnecting the B circuit where the power stays on constantly and adding a second wire from connection 7 to connection 4 on they relay. This worked while circuit B is not connected but not when it is. Changed the wires, changed the pumps.

Any advice is helpful. The system does fill even though both pumps are on but would like to stop the relay from buzzing and have only one pump operational at a time. I have attached drawings to aid my description.

Component Specs
Power in cable = 250V 13A
Mechanical timer = 240V
Pumps = 220-240V 3A
Relay = 240V 15A & 230V 30A


Les Jones

Well-Known Member
Most Helpful Member
When you say "valve" I assumed that you mean a solenoid valve but the way describe what is happening its sounds like your really mean a water level switch. Can you clarify this point ?


Les Jones

Well-Known Member
Most Helpful Member
This morning I have noticed that someone on the AAC forum has pointed out the error in the connection to pin 7 on the relay. I had not looked at the schematic in detail and was just working from you description which makes sense. Overnight it occured to me that after the top level switches switches off pump A some water may still be flowing into the real pots from the dummy pot as the soil absorbs the water which would cause the water level in the dummy pot to go down. This would cause the level switch to close again so the pump would restart. this may happen a few times until the soil has taken up all of the water it can absorb. A similar thing will probably happen when pumping out the dummy pot. I can't understand how both pumps could be on together unless it was when the relay was behaving like a buzzer and the power was being rapidly alternated between the two pumps.

Not open for further replies.

EE World Online Articles