Central control systems make it possible to program, monitor and operate one or several irrigation systems from one centralized location -- a personal computer. But the convenience doesn't stop there -- some central controls can also manage the functionality of other on-site systems, including lights and security. For all these reasons, contractors are implementing central control systems for a broader range of applications than ever before.
Getting in Control
By Lynette Von Minden
We’ve all wished that we could be in multiple places at the same time. Of course, that’s not possible — or is it? Today’s irrigation technology has transformed that wish into a reality for anyone tasked with the day-to-day operations of one or more properties. Central control systems make it possible to program, monitor and operate one or several irrigation systems from one centralized location — a personal computer. But the convenience doesn’t stop there — some central controls can also manage the functionality of other on-site systems, including lights and security. For all these reasons, contractors are implementing central control systems for a broader range of applications than ever before.
Central control systems can be customized to match the specific needs of just about any customer, budget, site and application. For example, contractors hired to maintain properties within a homeowners association (or within several homeowners associations) can manage irrigation systems, security gates and lighting without sending employees out to each residence or common area. Residential property management companies, apartment complexes, grounds maintenance personnel and commercial property managers can also save time and money by operating multiple systems from the comfort of their own offices. Cities have also used central control systems to manage irrigation at multiple parks and sports fields from a single computer.
The basics of central control
Central control software allows managers and property superintendents to create customized computer programs to automatically operate the satellite controllers or two-wire decoders that open and close irrigation system valves. A central control system can monitor and adapt system operation and irrigation run times in response to conditions in the system or surrounding area. These systems can also provide historical data for detailed analysis and reporting of what ran when and the amount of water used. More advanced systems can integrate weather stations, flow meters, rain sensors and wind sensors to automatically make any pre-designated adjustments to system run times and watering schedules.
Components in a typical central control system include a computer, communications equipment, field controllers and sensors. Communications equipment — such as a telephone, radio modem or fiber optic modem — is located at the central computer and at each of the sites being monitored. Cluster control devices are located on-site to monitor and control the system equipment. Connected to the irrigation valves, sensors and other field equipment on-site, these devices receive parameters and scheduling data that an operator sets up using a central computer.
Advantages of central control systems
Central control systems offer a broad range of advantages to anyone faced with operating irrigation systems for large sites or multiple locations:
Convenience. Being able to make individual adjustments to multiple irrigation systems spread over a geographic distance can save significant time and money for the operator by eliminating the need to travel to each site. Changes to irrigation schedules can be made quickly and easily from the comfort of an air-conditioned office. Some central control systems can even be set up to control other automated features of a property, such as lights, fountains, security systems and gates. Constant monitoring. Sensors at each location can detect high-flow, low-flow and no-flow situations, alerting managers to potential problems before they become catastrophic. Not only does this inform the operator of a problem quickly, resulting in a more effective use of time and money, but it can also save turf and landscapes that could be severely damaged due to an undetected malfunction. Water efficiency. With central control systems, managers are able to automatically change watering schedules with a few simple keystrokes on their computers. Weather stations at each location can report back evapotranspiration conditions to make automatic adjustments. Rainfall intensity can even be monitored and compared to the soil infiltration rate to determine how much water makes it to the plant’s root zone. Healthier plants and turf. Central control systems help ensure that each landscape receives the right amount of water, not too much and not too little, resulting in healthier plants that are better able to resist infestation and disease. Safety. Being able to quickly and easily change watering schedules is especially important when irrigating commercial, recreational and other public areas with high levels of pedestrian traffic. Cost savings. Besides the obvious money saved by spending less time and fuel travelling to and from the site, central controls allow users to coordinate activity between the controllers on the site and manage irrigation demand so that pumps operate at peak efficiency.
Choosing a central control
Before deciding which central control system is right for a particular project, it’s important to closely examine several factors. Because every situation is different, the weight assigned to each decision factor will vary. Determine the customer’s “must-have” features and let those findings lead you to the central control system that best fits the project.
1) Project size and complexity. The overall size and complexity of the irrigation project are primary considerations when choosing a central control system. The use of satellite controllers or two-wire decoders at the project site will also dictate the type of central control system that’s most appropriate, as some may only be compatible with one or the other, but not both. Certain types of central control systems are designed for one larger site while others are specifically used to control multiple sites.
2) Water conservation objectives. A central control for an irrigation system in a particularly drought-prone or arid region must contribute to water efficiency. The best central control system in this type of situation will need to include a high level of programming flexibility to accommodate changing water restrictions. The ability to interpret evapotranspiration (ET) data and link to weather stations and rain sensors is also important, as the watering schedule can be suspended when significant precipitation begins to fall. Although water is not always priced to encourage its conservation, the expense of the electricity used to run the irrigation pumps can quickly add up. In this case, the central control system will need to coordinate irrigation demand so that pumps are operating at peak efficiency.
3) Water type and associated reporting needs. The use of municipal water or reclaimed water affects the choice of a central control system. Because reclaimed water may contain potentially harmful chemicals or bacteria, its use must be reported to environmental agencies. Clients located in regions supplied with water from an aquifer may be asked to document their usage so that local water agencies are aware of the demand being placed on the water supply. In most situations, systems using both municipal and reclaimed water will require flow sensors to measure the amount of water being used from both sources so that the system manager can create a report. It’s crucial to determine a customer’s reporting needs and make certain that the chosen central control system can meet them.
4) Watering windows. The amount of time that an irrigation site has available for water application — its watering window — can be dictated by the levels of pedestrian traffic and the number of outdoor events experienced throughout the day. At sites with a high number of pedestrians or outdoor activities, a central control system will need to quickly and easily accommodate scheduling changes.
5) System management. City parks and recreation departments may task various individuals with managing the irrigation of different parks or sports fields, with all of them using the same central control system for budgetary reasons. Certain multi-site systems are far better suited to meet the challenges of multiple users, so it’s important to find out how the system will be managed before selecting a central control system.
6) Communications options. There are two types of communication involved with central control. Primary communication is the type of communication used between the central control computer and the irrigation site; secondary communication is communication between controllers. A single-site project may only use one of the following communication methods — a PC-based network, telephone landline, cellular telephone, radio or Internet modem. However, in a multi-site application, the central control must often be capable of incorporating any combination of the aforementioned communication methods. This type of situation is common for contractors who manage multiple small to medium-sized irrigation sites for various clients, residential and commercial.
7) Flow monitoring. Flow monitoring is necessary to generate the water usage reports that businesses, cities and school districts often require. Because a valve’s actual flow is the best indicator of any potential problems at the site, operators can compare flow reports to the actual flow meter to see if variations exist. More advanced systems can be programmed to automatically react to these situations by shutting off one valve or the entire system based on pre-designated parameters. In a low-flow situation, the central control can even be programmed to purge filters automatically.
Central controls offer a tremendous degree of flexibility, convenience, efficiency and cost savings, making them extremely valuable for many irrigation projects. However, there are many decision factors involved and a wide variety of products available on the market. Upfront hardware expenses, installation and any recurring monthly costs will also be considerations when deciding which central control system is best for a project. It may be tempting to recommend a system with all the “bells and whistles,” but finding the best product with the most applicable technology at a reasonable price should be the ultimate goal.
By Lynette Von Minden is public relations counsel at Swanson Russell. Article provided by Rain Bird,www.rainbird.com.