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HTINews Article

AUTOMATED SYSTEMS WATER HOUSEPLANTS
By Stuart D. Snyder Bocasite@aol.com

Home automation has come a long way in the past five years. The market is overflowing with master control systems. Not to be overlooked however, are the many peripheral systems and devices that increase the versatility of the master control, and make it worthy of investment. The more things a master control system can accomplish, the more practical it becomes. Among the peripherals currently available are the Mirage Series Automated, Precision, Micro-Irrigation (APM) Systems for watering decorative plants in homes and offices. That is the subject of our discussion.

Living plants impact our lives and businesses in many ways. Beyond the food, shelter, shade, medicine and clothing they provide us, space research over the past twenty years has unlocked technical attributes of plants useful in helping us provide healthier home and work environments. Indoor air pollution (IAP) has become an issue to be reckoned with. The EPA, in its 1989 Report to Congress, called indoor air pollution, one of the most serious environmental hazards affecting our health, and called for action... we spend 90% of our lives indoors. Despite the warning, our government is doing little about it, except for a poorly funded Indoor Air Division of the EPA, but the environmental dangers persist. For these reasons, the ecology of building interiors has become an important strategy for overcoming IAP... something we can do ourselves. NASA and Russian research demonstrated a decade ago, higher plants' ability to absorb and assimilate many airborne toxins that pollute our homes and work places. It gives us a new tool to help improve these spaces. Other important research during that period came out of Texas A&M. It demonstrated positive, human physiological responses when around living greenery. Landscaped environments were shown to be great stress-reducers. Because we spend so much time indoors, use of houseplants now takes on a new meaning. Automated plant-care systems bring an advanced level of practicality to green use indoors.

Interior plant-care is a labor-intensive task, particularly irrigation, making it a logical target for automation. Boca Automation, Inc. of Boca Raton, Florida has developed automated, precision micro-irrigation (APM) systems to relieve the maintenance burden of interiorscape installations. While not meant to replace human plant-care, they are capable of completely eliminating the irrigation task in many projects. This is a convenience for homeowners and an important cost-saving factor for office managers.

APM technology refines sprinkler and drip irrigation technologies that preceded it. It is neither, but is a precisely controlled flow system specially engineered for interior use. It permits complete building coverage with automated service, particularly for containerized plants in furnished, residential living areas and office work space. They overcome most of the drawbacks of self-watering containers. Techniques were developed by Boca Automation to integrate central systems into new building structures, or to retrofit them into existing ones. They are fully compatible with microprocessor-based energy management and other control systems. The interface is a simple one, requiring only a dedicated power receptacle, controlled by the master system. Mirage solenoid valve controllers simply plug into the receptacle. Many configurations are available to accommodate a wide variety of market needs.

The two main divisions of Boca Automation’s patented APM systems are, low-pressure and high-pressure types. The difference lies in the method of developing the dynamic forces that permit water to flow through the system. Low-pressure versions use a plastic reservoir that has a small pump integrally mounted. They are used when connections to a cold water pipe are not readily available. High-pressure systems connect in some way to the cold water plumbing, and rely on structure water pressure to motivate flow. Only Mirage Series, high pressure systems are available for professional installation. There are several common elements in all versions. The first has to do with the length of the watering cycle. Short pulses of water flow are used, only 10 or 20 seconds in duration, just enough to furnish the limited moisture requirements of indoor plants, yet provide the best system safety and control. In the average installation, these small doses are repeated twice daily, at regular intervals. The short cycle reduces tubing networks to minimum pressurizion (no more than about 40 seconds each day), providing an important safety feature. It must be kept in mind that indoor plants require much less water than their outdoor cousins. APM systems are designed to consistently maintain a user-selected, optimum level of moisture for each plant, providing a practical balance of moisture and oxygen around the roots. They are not well suited for quickly wetting out dried plants. The advent of automated systems disproved many old dogmas about how indoor greenery should be watered. Conventional wisdom called for potted planters to dry out over a period of time to restore oxygen levels, after which they are doused with copious amounts of water to thoroughly wet them... which then displaces oxygen however, and creates an unnatural wet-dry cycle. That may be a practical regimen to use with manual irrigation methods because of the convenience factor, but is not necessary with the new, automated techniques. Frequent, gentle watering cycles are the preferred method, as moisture has a chance to diffuse through the soil mass between irrigation cycles, without purging the system of oxygen, nor permitting soil dehydration. Root rot and moisture stress are minimized. Less water is used as surface tensions don't have to be overcome in rewetting dried soil. Runoff and overflow are eliminated. Frequent cycles and precisely controlled small doses are not practical using manual irrigation techniques, nor with sprinkler systems.

A second common characteristic of APM systems is that both versions use special controllers that power the activating elements of the systems (pumps or solenoid valves) for very short periods. The control center is the heart of the system. It determines when irrigation cycles occur and for how long. Mirage III, high-pressure versions use electronic controllers containing integral solenoid valves. Solenoid valves are the hydraulic equivalent of electric switches. A master control timer provides a one minute "power window" at the dedicated power receptacle, just long enough for the controller to activate the solenoid valve for 10 or 20 seconds, causing flow to occur during that period. After the controller shuts down, the power window also shuts down. This arrangement provides an important safety factor. There is a double-tiered control sequence, preventing runaway irrigation cycles and flooding. The first timed sequence is from the master controller, the second is from the solenoid valve controller’s electronics. Mirage System controllers contain switches that toggle between 10 and 20 second irrigation cycles, determining the duration of the cycle. They are also designed with remote control jacks that allow the user to manually control flow with a thumb switch while adjusting emitters at planter locations. This is necessary during installation, and for readjustments. Water pressure regulators drop irrigation system pressure at the solenoid valve outlet, to 25 psi or less... another safety factor. They are the hydraulic equivalent of voltage regulators. Another common thread has to do with the fact that these are central systems, with control centers mounted in convenient locations such as garages, laundry rooms, cabinets or basements. The water distribution tubing network is routed throughout the structure to the many existing planter locations (and potential planter locations). Tubing is installed to remote locations to service built-in planter pits, boxes, or free-standing container plants. The routing is chosen for its aesthetic and technical practicality, to be hidden as much as possible, as are cable runs. Tubing is generally flexible, small-diameter cross-linked polyethylene (PEX) or CPVC, determined in large measure by local building codes. These are plumbing-grade materials. This type of tubing is easy to install but as with everything, care must be taken. To eliminate errors, tubing systems are checked for leaks before partitions are sealed. Fittings are plastic, solvent welded (CPVC) or brass slip-in fittings are used, secured with crimp rings (PEX), much the same way that coaxial cable fittings are installed. Whenever possible, routing is through wall partitions, ceiling plenums, basements, attics, crawl spaces, etc... any place the tubes can be hidden. The best and most cost-effective installations are generally those pre-planned before construction, where tubing runs can be designed into concrete floor slabs, wall partitions and ceiling plenums. In this way, the irrigation system can be fully integrated into the building structure. Various flow control devices are installed in the tubing lines to control flow volume, pressure and direction wherever necessary. Of these, check-valves are the most useful. The tubing network must be filled with water at all times to eliminate the need for time wasting air purges at the beginning of each irrigation cycle. Check-valves provide that control. They operate in one direction only; the hydraulic equivalent of a diode. The other common element in all APM systems is an adjustable, mini-valve/emitter at each plant, which permits the delicate adjustment of water flow during the very short watering cycle. This is a tiny needle valve that can be closed down to permit only a few drops to issue during the 10 seconds, or opened to permit application of greater volumes. A gentle stream of water impinges on a very small area of the soil surface and diffuses from there. These emitters also provide system flexibility by permitting a station to be closed down when a plant is removed, or to provide a watering station for future use. When larger plant materials are installed on a system, other emitters and more frequent irrigation cycles are used. Emitters at small plants on such networks are turned down for very low flow rates. Emitter tubing used at the plant locations is small diameter, generally clear plastic, to reduce visibility. A number of plants can be fed water from each emitter tube by branching them (with an adjustable emitter at each plant). Tubing branches of this type can traverse large rooms. Planter boxes, beds, pits and shelves can be serviced with these systems as well. For the larger planter groupings, irrigation manifolds would be used, terminating in emitter tubes for each plant, with the adjustable, mini-valve/emitter providing fine-tuned flow control. A unique feature of the Mirage III APM system is that special irrigation receptacles can be used in homes, mounted in walls at convenient locations around the perimeters of furnished rooms, in much the same way that TV antenna plates are used. They access the irrigation water carried by tubing networks within the partition. Small diameter, clear plastic emitter tubes are simply plugged into these receptacles to service nearby containerized planters. "Nearby" can mean hidden tubing runs as long as about 50 feet if necessary. Up to about 10 small-to-medium sized plants can be serviced from each receptacle (by branching). They can be on furniture or floor placement, on wall unit or book shelves, in hanging baskets, on kitchen or office file cabinets, in greenhouse windows, etc. Inactive receptacles are simply plugged until needed. Small-bore tubing runs outside of wall partitions are made less obtrusive by routing under carpeting around the perimeters of rooms, or behind functional and decorative baseboard moldings if necessary. Connections are made and emitter tubes are brought to the surface, routed to the planter and terminated with an adjustable emitter.

With proper planning, branches of the system can generally be extended to outdoor locations, to water limited numbers of potted plants on patios, sun decks, etc.

While it is recognized that most home automation specialists have electronic backgrounds, the mechanics of installing electro- hydraulic networks, like Mirage III Systems, is similar to making cable runs. One also does not have to be a plant expert to deal with APM systems. In fact, most installations have been by contractors with electronic orientation. APM systems broaden market opportunities for home automation specialists. Components, project design services, dealerships and training are available from Boca Automation for interior irrigation systems. For more information, call (561) 272-9838.

About the author: Stuart D. Snyder is President of Boca Automation, Inc., a company specializing in automated facility management systems. Mr. Snyder has written magazine articles and the books, Building Interiors, Plants and Automation (Prentice Hall, 1990), and Environmental Interiorscaping (Whitney Library of Design, 1995).