I am trying to automate the irrigation and I read that buying a 24 VAC solenoid valve normally closed would be the best. 12V ones being less reliable due to heat and the big-AC ones clearly not passing safety regulations.

I found lots of decent prices like http://s.aliexpress.com/iq6vMnQr but somehow they missed to write what transformer do I need to power one or two. I dont want to spend too much the 220v AC to 24v AC, so I need to know how powerful it should be.

  • Most manufacturers neglect to list how much power it takes to hold a solenoid. They don't even list it in their label. You may have to contact the supply house or manufacturer for more information. Depending on the size of the valve it could be a less than a watt up to hundreds of watts. – ArchonOSX Jun 18 '17 at 10:42
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    Aliexpress is Cheese junk and that disturbing lack of support is typical. That and terrible build quality is why the price is so low. Buy from reputable manufacturers. – Harper - Reinstate Monica Jun 18 '17 at 14:49

3/4" solenoid valves use around 20 to 30 VA. to open. Look on the name plate and it should say what the VA. or watts is. You can buy a ( 120/208/240) input X 24 volt output transformer Rated at 60 va.for about $50.00. I saw on Amazon a Siemens MTO100C 120/208/240volt X 24 volt, 100VA. for about the same price.

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