The automatic irrigation just came on!
 

Ok, we just had almost 4 inches of rain yesterday, and the sprinklers came on today on schedule. I had my DH shut the system off. I really didn't think it would even come on today.

Depending on your system, you probably have a sensor attached to your roof. The sensor knows it's dry right now, so the sprinklers will come on. Some of the newer systems (Hunter and otherwise) have ground sensors, but you have to be very careful with them -- they break easily because they're very close to the surface and, if you do new landscaping, odds are the wires will get cut and no more sensors.

I am not sure it should come on so soon after heavy rain if the rain sensor is working properly and adjusted properly. My rain sensor, not in-ground, has two adjustments. One is for the number of inches of rain before it shuts the system off. The other is for the length of time to dry out allowing the system to function again. You might check your sensor to see if it is adjustable. (It means climbing a ladder or step ladder).

Last, but not least, I have found rain sensors have a limited working life. You might want to check yours regardless of age. The next time we get a heavy rain check to see if your system will activate. If it does them you will know it needs adjustment or replacement.

Hope this helps.

If you have a Hunter controller. When you open the door in the top left corner is a bypass switch for the rain sensor. Make sure it is flipped to active and not bypass.


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John is definitely correct! Also, the Hunter systems gauge on the outside of your garage has a dome on the top which calcuates your system, not only by rainfall and moisture but also sunlight. So, depending on the angle your home faces, trees which could be casting a shadow on the sensor, a neighbors roof line, all play a part in that sensor.
As I am typing this, I was surprised to hear my system also go on.
Earlier today, as we are doing a small landscape project this weedend, I stopped by the nursery to pick up the rest of my plants which I couldn't fit in my car on Wednesday and speaking to the attendant, she made a comment that she needed to water some of her plants as they were wilting from lack of water. I was shocked but when I brought my plants home and felt the soil, they were dry and had been outside yesterday.
But do make sure, as we get into the rainy season, like John said, you set your irrigation to Active, not Bypass and check it regularily and also check what your seasonal adjustment reads. That will fluxuate on its own, by the sensor, by percent, up and down. For example, if you have your lawn rotors set for 50 minutes but your seasonal adjustment reads 50%, your irrigation will only run for 25 minutes.

The rain sensors really seem to be hit and miss, all they are is a small cork and when it dries out it turns the system back on if it was ever off. Should show OFF in the window if the sensor turns off the system but I don't think mine has ever done this correctly, sensor switch has to be in active. If it rains a good rain I just turn it off manually for a few days, but then that only works if you're here.

Good suggestions and these two videos might help too:

How to Program the Hunter Pro C Controller, click below:

[ame=http://www.youtube.com/watch?v=V9aOb_m1QUM]Webbtraining1 - Hunter Pro C Irrigation Control Timer - YouTube[/ame]


How to Program Solar Sync Module, click below:

[ame=http://www.youtube.com/watch?v=NfugRI0YqEQ]Solar Sync - Programming - Part 2 of 2: Programming the Solar Sync Module - YouTube[/ame]

The highlighted statement in the quote is very true. The idea behind the sensors makes sense; unfortunately, they are more theoretical than practical. I have heard people with a lot more knowledge about irrigation systems, including those whose business it is to work on them, describe the sensors as "less than useless." These folks say that the best way to deal with the system is to turn it off manually during times of heavy rain, then turn it back on. I was told even to consider turning the system off altogether—or at least considerably reduced—during the winter when plantings are dormant. Thanks for the videos; sometimes I feel as though one needs a PhD to understand that box in the garage....

of course it came on. these are very simple systems. if it is raining then they will not come on during the rain. if it is not raining then it will come on as per the schedule. the sensors do not 'sniff' the air and determine if and when they should or should not come on. this is just not that sophisticated a system.

I have best results of turning it off and use my own common sense. My system comes on Tues. and Fridays. If it rains Monday, and my rain guage shows enough water, I'm turning it off, don't need watering the next day. If my sprinklers do water, it provides .500" of water so if it rains near that amount I will save running the system and the money it costs which is quite expensive. It's like playing a game and I enjoy it.