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What is a weather-based irrigation controller? How is it different from a standard controller?
How does it work?
What type of sites benefit from this technology?
What type of weather-based controllers are on the market?
Where can I buy one?
Who can install it for me and what do they need to know?
Are there any rebates?
Addtional Product Information

What is a weather-based irrigation controller? How is it different from a standard controller?photo of an ET irrigation controller
A weather-based irrigation controller, also sometimes called a smart controller or ET controller, automatically adjusts the watering schedule based on local weather conditions. The controller reduces the amount of watering when the weather cools down, and adds time when it heats up. Smart timers apply irrigation only when needed.

A standard controller requires that a person make manual changes to the irrigation schedule throughout the year. Often watering times are not adjusted at all, and much water and money is wasted from over-irrigation. ET controllers take the guesswork out of how much to water and automatically make timer adjustments for you.

How does it work?
Weather-based controllers use local evapotranspiration* (ET) data to determine irrigation requirements and the watering schedule. As ET values change in response to temperature, wind, humidity, and sunlight so does a plant's need for water. As ET values increase and plants require more water, the controller uses this information to add more time to the schedule. Smart controllers also use site factors such as microclimate, plant type, soil type, slope, and method of irrigation to inform the watering schedule.

*Evapotranspiration is the amount of water evaporated from the soil and plant surfaces and the water transpired from a plant's leaves.

What type of sites benefit from this technology?lawn with border
Studies have shown properties with a history of over-watering will see the greatest savings. Typically, larger properties with turf are good candidates for weather-based irrigation controllers. Sites where customers don't want the hassle of making adjustments to their timers are also a good match. A knowledgeable landscape contractor or vigilant homeowner can get the same results by making manual adjustments to a standard controller.

ET controllers will not compensate for poor irrigation design or efficiency. Irrigation equipment should be in good working order before investing in weather-based controller techonology. If you are unsure about the performance of your irrigation system, consult and irrigation specialist and ask for an audit.

What type of weather-based controllers are on the market?
Like most products, smart controllers range from simple to sophisticated and everything in between. Some are tailored to residential properties, while others are meant for large-scale commercial landscapes. Smart controllers can be divided into three categories based on the type of weather data they use: historical, on-site, signal-based.

Timers using historical weather data typically contain pre-programmed climate information. These controllers oftren reset the watering times only on a monthly basis, but can still offer significant water savings. Timers using historical data are generally cheaper in price, relatively simple to use, and a good choice for typical residential properties.

    On-site Sensorsphoto of a wireless weather station
Sensor-based controllers gather daily information on site to make irrigation adjustments. Sensor equipment may include mini-weather stations, rain and temperature gages, and soil moisture sensors. Many sensors are going wireless to simplify the installation process. Well-placed sensors can be very accurate, with the advantage of making site-specific watering adjustments. Many companies sell "add on" sensors and equipment which allow standard controllers to function as a smart controller.

Signal-based controllers regularly receive weather data from radio, telephone, cable, cell, web, or pager technology. Signals often come from local weather stations collecting evapotranspiration data. Controllers using data from a signal often have an annual service fee. Without an activated signal, these controllers operate like a standard controller and will not make any automatic watering schedule adjustments. On the flip side, there is no on-site sensor equipment to maintain or replace. Higher end signal-based controllers offer additional options such as online programming, leak detection, and email alerts.

Where can I buy one?
For now, the best place to start is with the manufacturer. This list of weather-based controllers will link you to manufacturer websites and indicate which models are available locally. Models not offered locally can usually be purchased from an online source.

Who can install it for me and what will they need to know?
An irrigation specialist or landscapers with solid irrigation knowledge should be able to install a weather-based controller. The timer will likely need minor adjustments in the first few weeks to refine the watering schedule.

Site information needed to program the controller includes: plant type, soil type, root depth, type of irrigation at each station, precipitation rate of the sprinklers for each station, slope, sun/shade, and wind conditions.

Are there any rebates?
Rebates will be coming Spring 2011.

Addtional Product Information:
Overview Table - includes manufacturer links, price range, locally available products
USBR Technical Review of Weather and Soil Moisture Based Landscape Irrigation Scheudling Devices - detailed report
USBR Summary Table - product comparison
Smart Water Application Technologies (SWAT) - third party product performance testing


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Last updated: 11/24/2010 9:32:06 AM