rainsensor1.jpgWell, that sure was one hot and dry summer! (Okay, that could be the opening line for nearly any post about any summer in the past few years.) But more importantly, this past hot and dry summer followed a very very dry winter in the high country. Which means for us gardeners and homeowners in the Pikes Peak area, the chance for watering restrictions is very high next year. So it’s a good time to introduce some tools that might help use water more wisely in your landscape. In this post, we’ll look at rain sensors for your sprinkler system.

Most in-ground, automatic sprinkler systems work the same way. Zones are identified and mapped. A set of sprinkler heads and nozzles are installed for each zone with PVC pipes connecting them. The zone pipes are connected to a valve control box that is then run by a timer. The timer can be set to have the sprinkler run on certain days for certain amounts of time. Many of us set our sprinkler timers at the beginning of the season and then let it go from April through October. As mentioned in previous posts, occasionally observing the system throughout the season while it is running to catch any problems will help save water (broken nozzles shooting geysers in the air, for example). And adjusting the running time throughout the season is very good second step – plants don’t need as much water in April as they do in July.

rainsensor2.jpgA rain sensor system is an ideal next step to further increase the efficiency of the sprinkler system. The actual rain sensor is installed outside in an area where it won’t be sheltered from rain. A second piece, the transmitter, is connected to the sprinkler timer. Once it rains a bit (as little as .05″), the sensor tells transmitter it is wet, and the transmitter stops the timer from running the sprinkler. (It does this by actually interrupting the connection between the timer and the valve control box. So the timer still thinks it is running a program, but the signal isn’t getting to the control box that opens the valves and allows water to run out to the sprinkler zones.) And once the sensor dries back out, it lets the transmitter know that it is okay to have the timer run the next scheduled watering. There are wireless and wired versions of rain sensor systems. Wireless is especially convenient and gives you much more flexibility when choosing where to install the sensor outside.

rainsensor3.jpgThe trickiest part of installing the rain sensor system is connecting the transmitter to the timer, especially if you have an older timer. Many new timers have connections already built-in for attaching a transmitter. Take a look at your timer and see if you can see connections marked for a sensor. If not, try searching online for information about your specific timer. As a last resort, you might consider purchasing a snazzy new (but inexpensive) timer to make installing your rain sensor super easy.

The not-as-tricky-but-still-very-important part of installing the rain sensor system is placement of the actual sensor. Don’t place the sensor where it can be hit by water from the actual sprinkler system! (Though I was so excited to get my sensor that I first tested it by starting my sprinkler and then holding the sensor out under one of the sprays. The system stopped watering after 10 seconds!) Don’t place it under a tree or even next to a tall structure that might block rain if the wind is going a certain way. Ideal places include the top of a tall fence post, on the end of a roof eave, or even on its own special post out in the middle of an open area.

Costs vary for different systems, but the wireless system shown in these photos can be purchased for about $35 to $40.

Just think how nice it will be to know that you won’t be “that guy” whose sprinkler is spraying merrily away in the middle of a rain storm!