WHAT IS A SMART IRRIGATION CONTROLLER?

Smart irrigation controllers or timers have built-in water-saving irrigation features, including a sensor that adjusts the optimal irrigation time based on local weather conditions. Intelligent irrigation controllers help provide a healthy, beautiful landscape while reducing water use. This not only saves water, but also reduces costs for homeowners.

THE TYPE OF SMART IRRIGATION CONTEOLLERS

Climate-Based Irrigation Controller

Climate-based irrigation controllers also referred to as evapotranspiration (ET) controllers use local weather data to adjust irrigation schedules. Evapotranspiration is the combination of evaporation from the soil surface and transpiration by plant materials. These climate-based controllers gather local weather information and make irrigation run-time adjustments so the landscape only receives the appropriate amount of water.

There are three basic types of ET irrigation controllers:

Signal-based controllers use meteorological data from a publicly available source and the ET value is calculated for a grass surface at the site. The ET data is then sent to the controller by a wireless connection.

Historic ET controllers use a pre-programmed water use curve, based on historic water use in different regions. The curve can be adjusted for temperature and solar radiation.

On-site weather measurement controllers use weather data collected on-site to calculate continuous ET measurements and water accordingly.

Evapotranspiration controllers have been shown to reduce outdoor water use. In Las Vegas, Nev., homes with ET based controllers saw an average of 20 percent irrigation reduction compared to homes with homeowner-scheduled irrigation. Additionally, a study conducted on St. Augustine turfgrass showed an average irrigation savings of 43 percent in the summer compared to homeowner-scheduled irrigation, with no reduction in turfgrass quality. The accuracy of ET controllers depends on the equation parameters. Most ET controllers cost between $250 and $900. Professional grade ET controllers range between $900 and $2,500.

Soil Moisture Sensor Controllers

The second type of smart irrigation controllers includes soil moisture sensor controllers. Instead of using weather data, soil moisture sensor controllers utilize a soil moisture sensor placed belowground in the root zone of lawns to determine water need. The soil moisture sensor estimates the soil volumetric water content. Volumetric water content represents the portion of the total volume of soil occupied by water. The controllers can be adjusted to open the valves and start irrigation once the volumetric water content reaches a user-defined threshold. The appropriate threshold value depends on soil and vegetation type and usually ranges from about 10 percent to 40 percent. Soil sensors must be installed in a representative area of the turf; far enough from sprinkler heads, tree roots, sidewalks and walls.

Similar to ET controllers, soil moisture controllers have been shown to reduce irrigation, while maintaining turfgrass quality. Compared to homeowner irrigation schedules, soil moisture controllers had an average 72 percent irrigation savings and a 34 percent water savings during drought conditions. In some cases, studies have shown smart controllers will increase water use at sites that typically use less than the theoretical irrigation requirement. Typically, soil moisture sensor controllers range from $280 to $1,800. Difference in pricing depends on product manufacturer and end user, either residential or commercial customers.

SMART IRRIGATION STARTS WITH PROPER SPRINKLER SYSTEM DESIGN AND INSTALLATION

A smart controller is part of a properly designed, installed, operated, and maintained automatic irrigation system. The timer is responsible for activating each valve and for the amount of water applied to the landscape.

It is important that an irrigation professional installs a smart controller to ensure it is set up properly for the water requirements of the landscape.