SMART CONTROLLERS What is a Smart Controller? Smart controllers automatically adjust watering based on daily weather data or soil moisture sensors. This helps plants receive appropriate amounts and frequency of watering. Some Smart controllers are known as, “ET” controllers.
What is Evapotranspiration? Evapotranspiration (ET) is the water lost from the soil through Evaporation and water used by plants, Transpiration. ET varies daily and by location. Four factors are used to measure ET: temperature, wind, solar radiation, and humidity.
How do the controllers get their daily information? Controller adjustments are based on data from some source, such as:
1. On-site sensor(s): Some controllers collect many, if not all, of the ET factors from mini “weather stations” installed in the landscape. This information is transferred to the controller daily.
2. Signal service: These controllers receive daily customized ET data via satellite or cellular service, gathered from a “network” of weather stations and then modified for a site’s unique location. Many of these controllers allow remote internet access for more effective water management.
3. Radio wave or the internet: These controllers access a free broadcast from a local state maintained weather station. 4. Moisture sensors: Sub surface sensors are placed in the root zone of representative areas in the landscape. As soil moisture reaches an optimum level, the sensor interrupts the controller’s electrical signal to prevent watering until dry.
There are pros and cons to each method:
1. Controllers that download thru satellite or cellular technology, or allow two way internet management of controller, have annual subscription fees, ranging from $100 to $300 per controller. Multiple year discounts may be available.
2. Sites with unique weather conditions or out of signal service range may require on-site sensors.
3. Controllers using on-site sensors have no subscription fees, but sensors may need to be maintained or replaced.
4. Some controllers are not true “ET” controllers, only modifying user created programming. Some only modify run time but not frequency. Why are “Smart” controllers important? Historically it has been less expensive to pay for extra water than to pay for the labor required to physically adjust each controller every time the weather changes. The compromise has been to only change the controllers when there have been major shifts in weather. This does not account for the majority of the water savings potential that can achieved with the micro adjustments on a daily basis. Since these controllers provide water savings without the additional labor required, they are a logical solution. In many cases the return on investment is 1-5 years, depending on historical water use on site, cost of water, and rate increases. Appropriate watering can also help reduce costs associated with replacing damaged property. What other features do Smart controllers have? Flow Sensing Use of a flow sensor can detect flow rates that exceed normal and, when combined with a master valve, the controller can shut down events such catastrophic pipe breaks or stuck irrigation valves to help reduce damage. Many also will provide a text or email alerts. Some controllers collect flow data to help manage water use. Flow sensing may be a challenge on sites where multiple controllers share a single water source or vise versa. Scheduling Engine Few people know how to accurately program standard controllers to provide the right amount of water and avoid overwatering and run off. Controllers that require entering each station’s unique characteristics, such as plant material and root depth, irrigation type and efficiency, soil types and slopes, and sun exposure can use these variables to create the appropriate programming. Central Control More sophisticated controllers can be networked together to allow for a single point of control, either on a single site or several sites, for quicker response to anticipated events such as rain. For single sites, controllers can share ET data and coordinate programming between field controllers to water within limited time constraints. What else should be considered when deciding on a Smart Controller? Existing irrigation coverage Smart controllers do not know the condition of the site’s irrigation system. Poor coverage can become apparent when hot spots develop where prior flood irrigated to compensate for poor coverage. While Smart controllers can be compensate for poorer coverage, even modest improvements in coverage will help get the most benefit out of the controller, not to mention savings. Water Use It takes the right amount of water to keep plants healthy. Calculations can be done to determine what that amount is. When sites water dramatically below that amount, it is known as “deficit watering” and plants appear stunted or starving for water. Installing and programming a smart controller may cause water use to go up; however, not replacing dead plant material makes it a good investment. Fine tuning and troubleshooting When a smart controller is installed, proper programming and fine tuning is critical to its success. Adjustments of each station’s unique characteristics, placement of sensors, and compensating for irrigation coverage all can impact the results. In some cases, when these steps are not taken, the tendency is to override the controller and enter traditional programming.