how to turn on my sprinkler pump!

[forgets]

so i'm looking into changing my sprinkler pump to be controlled by the elk instead of the little switch inside the weatherproof box outside.. so i've got a question.. the sprinkler pump is your normal flotec .. 230VAC @ 9.6A can i use a ELK-924 for the low to high switching for it.. ? namely what i'm looking to do is use elk's output 3 to turn it on.. i've looked at the ELK-9100 too, but i'd rather save some bucks since the 924 looks like it could get the job done.. neither one is waterproof so i'd just mount them in the waterproof box the old switch is in and run some low current wire into the box to switch it on.. what i want to know though is ... is the threshold of current draw too close to what the 924 can handle.. ? the pump is rated at 19.2A @ 115V or 9.6A @ 230V .. i'm going to be running it at 230V though.. so let me know.. show me some pictures or give me ideas as to how any of you have yours wired... i've tried looking for photo's and examples.. but i came up dry.. thanks in advance for all responses.

 

[DavidL]

forgets, go to a sprinkler supply place and buy an outdoor pump relay. Then, just use a standard elk controlled relay to switch the low voltage side of the pump relay. 24 volts AC just like the sprinkler solonoids on the valves. I have bought the pump relays as low as $40 on clearance.

 

[elcano]

I dont recommend using the Elk-924. Even if you use one of them for each of the 120v phases you will be below the 10 Amps rating. However, the pump is an inductive load. This mean that at the time of opening the circuit, the current will continue flowing in the ciruit, raising the voltage extremely at the relay contacts and thus, provoking an arc. This arc might burn your relay contacts prematurely.

I made my own relay module for my 240VAC water heater using this relay:
http://www.goldmine-elec-products.com/prod...p?number=G14855
However, a water heater is a resistive load, which does not cause the arc problems.

I think that the water pump relay is a good idea. Dont forget to check eBay.

 

[gduprey]

If induction is a problem, look into SSR's. THey can switch large loads and do not couple anything from the load into the control line, regardless of the size of the pulse. And SSR is opto-isolated from the load and non-magnetic.

Instead of a contact closure, you'd have to apply a small voltage (like 2 volts, usually) to the unit, but that is easy to do. The current draw is usually 10 to 20ma on the control side, so often any sort of digital output from a controller will work (with an appropriate current limiting resistor).

You can get SSR (solid state relay) in all sorts of current capacities at places like www.mouser.com and www.digikey.com and others. Great tool for hi volt/load interfacing to digital stuff.

Gerry