The problem is that standard irrigation timers just do not cut it when you have a large garden. We have such a garden with 29 separate watering zones, and we wound up with two clusters of timers in two buildings separated by some 200 feet, one cluster in a barn and the other in a basement.

This might not sound too problematic until you notice in passing that this flower bed needs more water or that shrub looks a little dry, or rain makes it necessary to skip all watering for 24 hours, or a high wind makes it pointless to have sprinklers on at all.

Any of these critical horticultural situations can turn into an inconvenient trek to the barn or basement only to find that the timer you want is in the other location. Then when you do find the right one you have to fool with a horrible user interface. The obvious solution is networking.

We looked around for remote controllable irrigation systems, and not wanting to spend thousands of dollars on commercial products designed for watering hundreds of acres we concluded that an X10 product might help.

X10 is a simple, low-speed, power-line network technology developed by Pico Electronics of Scotland but now out of patent. While it is not the most robust or high-performance network offering it is cost-effective (cheap) and adequate for this kind of application.

Networking in the Rain
After much research, we also settled on a neat device called the Rain8 from WGL & Associates. This is a tiny box with three connectors: one for programming, one for connecting to a separate power-line interface module that converts the X10 signals into a custom serial interface for the Rain8, and a terminal block with eight connections (one for valves or "zone," one common for all valves and two for the 12-volt power supply).

WGL provides a utility for programming the Rain8 that lets you set the X10 codes and maximum run time for each zone and two optional codes that trigger running the zones in sequence with a separate list of zone run times. There are two further optional codes: one that disables the unit and another that skips the next sequenced run (in effect, a 24-hour delay function).

We found a box to house the equipment (three Rain8s, power supply and power-line interface), wired it all up (click here for some pictures and links to all of the components), and tested it by replacing the timers in the barn.

With a stand-alone X10 controller plugged in next to the unit, there were no problems. But from the computer room being controlled by a computer through a power-line interface, nothing worked.

We assumed the problem was signal degradation because of the power circuit being about 200 feet long. But after buying a new power-line interface for the Rain8 setup and trying the same on the computer, installing an X10 signal booster and an X10 phase coupler, and after much fooling around, we still couldn't get it to work.

It turned out that simply moving the computer's power-line interface from a socket powering several computers to another a dozen feet away with nothing plugged into it fixed the problem. Such are the curiosities of X10.

So what software to drive the Rain8 setup? After much research, we concluded that there is nothing better than HomeSeer. There are some interesting alternatives, such as the freeware MisterHouse, but in terms of ease of use and power, HomeSeer was the hands-down winner.

HomeSeer really is a fine piece of engineering with a good interface and good documentation, and can run scripts written in VBScript, JavaScript and Perl, which has led to a large collection of free and commercial add-ons. HomeSeer offers an optional telephone interface that provides a multi-box voicemail system, and with the right hardware HomeSeer provides a Web interface so any computer in the house can trigger or change the irrigation system. We are modifying it so we can walk around the grounds triggering zones using a wireless connection from a PDA.

One Rain8 sprinkler controller, 24-volt AC 300ma transformer, RS232 cable, data cable and a PSC05 power-line interface costs about $100; additional Rain8s cost about $80. HomeSeer costs about $150.