| Most states and/or cities in the U.S. now | | | | increased placement options offset the cost. |
| require rain sensors by law. They are simple | | | | Most wireless units come with by-pass |
| to install and pay for themselves quickly. | | | | switches built into the device. |
| | | | |
| For this reason every lawn sprinkler system | | | | Some digital controllers also offer by-pass |
| should have a rain sensor. The rain sensor | | | | options for both wired devices and wireless |
| determines whether or not enough rainfall has | | | | rain sensors. No matter the type of rain |
| occurred in order to skip an irrigation | | | | sensor type that you choose, all rain sensors |
| cycle. | | | | offer many advantages over not adding this |
| | | | detector to your automatic sprinkler system. |
| There are 3 basic types of rain interrupters. | | | | |
| They all serve the same purpose: keeping your | | | | Some of the immediate and long term benefits |
| system from over-watering the turf or your | | | | include: |
| garden. How does it do that? | | | | |
| | | | - Saves Money. Whether you pay for city water |
| The electrical connection between the sensor | | | | or spend electricity running a pump, the |
| and your sprinkler system controller is | | | | money you save over time will more than pay |
| interrupted when a certain amount of rain | | | | for the rain sensor. |
| triggers the device. The sensor breaks the | | | | |
| electrical connection so that electricity | | | | - Extends Sprinkler System Life Span. |
| cannot flow to either the sprinkler valves or | | | | Sprinklers are made up of gears and other |
| to a pump start (if your system is on a well | | | | parts that move. The less the sprinkler parts |
| without a pressure tank). | | | | are used, the longer they last. |
| | | | |
| One type breaks the connection by weighing | | | | - Protects Water Resources. By limiting the |
| the water in a rainfall collection cup. The | | | | over use of your sprinkler system, rain |
| problem with this type is that leaves, | | | | sensors reduce excess water run-off that |
| sticks, or the occasional lizard will find | | | | carries fertilizers and pest control |
| its way into the collection cup and therefore | | | | chemicals into our shared water supply. |
| turning off the system. | | | | |
| | | | - Conserves Water. Less water is wasted when |
| The next type uses electrodes to determine | | | | less supplemental water is needed for your |
| how much water is in the collection cup. This | | | | turf and in your garden. |
| kind of rain sensor device also has a system | | | | |
| problem of collecting things other than | | | | How much money can you save with a rain |
| rainfall in the collection cup. | | | | sensor device? It will vary based on your |
| | | | water source (city, re-claim, or well) and |
| The expansion disk type seems to be the most | | | | where you live (water costs, electrical rate, |
| popular. This kind of sensor does not use a | | | | climate). |
| collection cup; instead rainfall causes cork | | | | |
| disks to expand. This device uses a pressure | | | | Here is one example that demonstrates the |
| switch to break the electrical connection. | | | | benefits listed above: Seminole County, |
| These can be adjusted in increments of ¼" | | | | Florida. System Description: |
| to the desired rain fall setting. These | | | | |
| adjustments can be configured to kick in from | | | | Intended to sprinkle a 1/4 acre of turf |
| 1 to a 1/2" of rain has fallen. | | | | calibrated to precipitate a half inch" of |
| | | | water every time the system runs. |
| The most important aspect of installing a | | | | |
| rain sensor is where to place it. It should | | | | - This schedule would equal 6,788 gallons per |
| be installed in an area that is unobstructed | | | | irrigation cycle. |
| by trees, roof over hangs, or anything else | | | | |
| that might block rain from getting to the | | | | - This system (on City Water) pays $2.30 per |
| sensor. | | | | thousand gallons. |
| | | | |
| If it is a wired sensor, placement is | | | | - Every time the rains sensor interrupts a |
| generally near the sprinkler controller. The | | | | sprinkler cycle, you would save $15.61 |
| wires should be connected inside the | | | | |
| controller's valve wiring panel. This allows | | | | According to a recent study in Florida, the |
| for easier electrical trouble-shooting of the | | | | use of a rain sensor device averaged a 45% |
| system as the sensor can be easily | | | | savings in water for single-family |
| disconnected. | | | | residential water usage. The next time you |
| | | | see a sprinkler system running in the rain, |
| Year by year, as technology improves, FM | | | | you now know it doesn't have to be that way. |
| sensors have become more popular. Although | | | | Rain sensors save money, save our environment |
| they are more expensive than the wired | | | | and save water. |
| devices, the ease of installation and | | | | |