ELK Sprinkler control question


Trying to figure out how to wire up 24VAC Solenoid type residential sprinkler valves to be controlled directly by the ELK. Dry contact relays won't work since I understand 24VAC needs to go to the valve to make it work. Could incorporate a transformer and a dry contact relay for each zone, but for 8 zones that would get real messy real fast. Could get the Elk to run a WGL Rain8net, but that gets expensive considering I'd also need to get a serial port expander (ethernet expander is already using the serial port).

I guess my question is: Do any of you control these types of sprinkler valves directly from the ELK, and if so, how did you wire it all up? Can the voltage outputs from the M1G drive a 24VAC sprinkler valve?

Really like this board... lots of info and great folks here.

I haven't used the ELK version, but you just need an SPDT relay that is rated at 24V 1 amp for each sprinkler valve. From what I can see the ELK M1RB Relay board should work just fine (those relays are rated at 7 amps @ 28VDC).

The key is that you need to use an external 24VAC power supply to drive the solenoids on the sprinkler values. I wouldn't use the ELK supply since the current required is very high. The relays on the ELK Relay board do the switching. You just program your ELK to turn on that output and that sprinkler valve should open.

For a group of sprinkler valves you would connect the 24VAC sprinkler valve wall wart power output to the COMMON terminals of the relays. The N/O connections from the relays would then go to the individual valves positive terminal. The negative terminal on all of the sprinkler valves are spliced together and connected to the negative/black wire from the sprinkler wall wart power supply.

The only extra thing I would do is add a fuse(s) on the output of the sprinkler valve power supply. Those solenoids tend to fry every 5-10 years or so and when they do they create a dead short. The fuse will protect the 24VAC supply from damage.

I've done all of this with off the shelf parts, but the ELK module should do the same thing. Since you have an ELK you could even monitor the power going to the relays with a spare input, that way you could be alerted when a solenoid fails and not risk your lawn/plants.
Yeah, what he said. :D I used the M1RB and it works great. The M1RB has LEDs as a bonus so you can see at a glance what relay is energized. I just ran a Cat5 from the M1 to where the Toro controller was. Kept the wall wart in the case and just ripped out the Toro and wired to the Cat5. See this thread. It include a link to BSR's how to which includes a wiring diagram.
Thanks for all the input guys. I like the doorbell idea Brian, thanks! I guess I'll order some stuff and start playing.
I have wired cat5 from my ELK M1 to my M1XOVR board in the garage and am looking for a 24VAC transformer to drive my irrigation solenoids at the valves.

1. Does anyone know how many amps I need the transformer to be rated at?

2. And any idea where I can pick one up?

3. Should I put a fuse in the 24VAC line and if so at what amps?


edit: added fuse question
I looked up several brands of irrigation controllers and the transformers included with them are all 24VAC and range from .5 amps to 2amps (seems like a big range). And the fuses range from .75amps to 1amps.

So I guess I'll look for something around 1.25amps as that's what my prior controller used and a 1amp fuse.
Both Home Depot and Lowes sell power supplies for irrigation control. I believe the one I have is 24VAC, up to 1A, but I guess it really depends on the valves. Do you have a brand name or model # ?
IIRC, "standard" 3/4" irrigation valves draw less than 0.5 amp. so assuming you are only running one zone at a time, 0.5 amp should be plenty. Radio Shack probably has raw 24VAC transformers also, but you would need to mount and cable them. the HD & Lowes type stuff should all be plug-n-play safe.
Ditto to what Wayne said. It looks like you are starting from scratch, but if not, you can also wire the existing sprinkler controller in parallel. That's what I did. The Toro controller normally works all by itself, but if needed I can override is(using the rain contacts), or come back and run each zone for some additional time as needed. The lawn is usually okay with only the controller, but I have some pots and hanging plants on the deck that get cooked by the afternoon sun. On hot days, they get an extra shot of water in the afternoon to keep them wet.
I do not have a controller besides the Elk. I plan on having the elk control the irrigation cycles and add manual override switches as well.

I picked up a 24VAC .650 amp transformer at home depot in the irrigation section, it was the only type they had. The solenoids they have showed a .4 amp in rush, and .2 running amperage. So I think the .65 amps should be enough.
My Elk is my sole sprinkler control.
Eight zones.
Two possible runs per day (or one or neither) all by keypad control.
Times of the two runs (or not) set by keypad.
Durations of each zone set by keypad.
Bypass on keypad.
Run all on keypad.
Run individual zone(s) on keypad.
All controls duplicated in Main Lobby touchscreens.

The power unit you describe sounds similar to what I use.

Let me know if / when the code would be of use.