Node Red Logic help - pump control

I have a logic question. For a water pump with an in built flow detection which does not work very well I have an external power socket in the 230V to the pump.

I have a flow meter and when the flow is >2L/min I turn on the waterpump (via the socket) and when the flow is <2L/min I turn it off. This way the pump always works (turns on) when needed.
when the pump is on 14-22L/min is flowing.

Now because of the inbuilt flow detection not working very well. When pouring water for a longer time (pump is powered and working) the pump is suddenly stopping, dropping the flow to ~7L/min. When I then stop pouring, the flow is 0 and when I start pouring the pump is powered again and going on like that.


I want to automate the detection of the “drop” from 14-22L/min to 7L/min an quickly power off and on the socket to the pump. how can I do that :slight_smile:

You could set a separate event node for the turn off.

The turn off is not the problem. Only <2L/min is turn off, which is in place and works. Or do you mean else?

You need a trigger that goes off at <~8L/min?

But what to do with the trigger? Turn off and on at <8L/min? Than the pump is always on… I would like to make it more safe and detect the “drop”. Else when taking less water, 2-8L/min the pump is off…

Edit: or do you mean to make a trigger “from >8L/min to <8L/min only”. That’s what I need, how to make that?

A trend sensor set in ha. It can detect changes like you describe.

I prefer to completely stay in node red for this… :wink:

Trigger node?

1 Like

Hm that might work, will try!

Implemented a little different but this lead me to the solution. it works. Thank your for your suggestion!

1 Like