Arduino Irrigation solid state relay vs spdt relay

Hi all,

Long time reader first time poster.

I am working on a project using the arduino to control my home irrigation system. The solenoids are 24vac with inrush of .4A and holding current of .2A.

My question is; What type of relay would be best suited? A spdt (low active) relay board, or a solid state relay that requires HIGH to activate?

Regards, Chris

looking at the application.

if you turn on 4 times a day for the next 100 years (4x365.5x100) = 146,200

you are withing the realm of both devices.

if you want to calculate the on time of them both, and the wattage of the coil vs. the wattage of the SSR, you might find the energy consumed could play a factor in your choice.

size ?

what you have on-hand ?

your application does not clearly favor one over the other.

flip a coin. or pick the one you have not used so you can get some experience with it.

Thanks Dave,

The energy consumed would be a factor. I was leaning towards the solid state perhaps for that reason?

Wouldn't the SSRs consume more power given they are less efficient, whenever I have used SSRs they have always required heat sinks for the waste heat generated, mechanical relays not so.

That is true and a good point. I suppose my reasoning is that they will only be used for 30 mins at a time maybe twice a week? With the spdt relay it would require a HIGH output from the arduino across all relay pins to keep the relays shut until use.

Yes I could re config the wiring re; normal open and normal closed but if the power were cut to the arduino but not the solenoid sit could result in all turning on at once?

Or the power consumption could be minute and I'm just being cheap!

So the real negative for the solid state relays is the 'leakage' and the heat generated during use because of the inefficiency?