Do I need to use a pump start relay? If so, how?

Here’s a sketch of my water system (pretty typical for a well I think). I have my Rachio running a bunch of drip zones for shrubs and a vegetable garden.

  • Well pump rate: 15 gpm
  • Well pump power: 1.5 hp
  • Well depth: 300’
  • Pressure tank volume: 32 gal.
  • Irrigation flow rate: unknown (still need to estimate, but all drip, probably fairly low?)

Do I need to use a pump start relay? It seems like the pressure tank may partially alleviate the need for this, but maybe I’m wrong?

If I do need to use a pump start relay, do these trigger off both the pressure switch and the signal from the Rachio (actually “or” Boolean logic)? What about the potential to “deadhead” the pump if an irrigation valve malfunctions and fails to open, thus causing the pump to run with no where for the water to go?

Related: Rachio Schedule vs. Well Pump (with data!)

I would imagine the pump is 120VAC. I see the “to house & irrigation”. Are those wires for the 120VAC and also something that goes to an irrigation controller? If you, do you what what kind of voltage, amperage or wattage, and DC or AC it expects?

@rcoe, the pressure tank with it’s switch should replace the need for a pump start relay.

1 Like

Why do you think you need a relay? Only scenario I can think of is you tapped into system between pressure tank and well pump. Not sure why you would but dependent on the pressure curve of the pump it might be okay but seems like a bad idea unless for some reason the pressure setting for the pressure tank is set too low to run your irrigation. Seems unlikely if your drip system is low pressure.