This article is about irrigation computers for controlling solenoid valves. The most important models available on the market are presented and explained what distinguishes them from one another and what criteria to look out for when buying such a computer.

Only those computers that are required to control solenoid valves are dealt with here. In principle, these can be imagined as electrical junction boxes, except that the cables are not connected here for a circuit, but for the switching of solenoid valves. Although two cables lead from each solenoid valve to connect to the irrigation computer, each additional valve only requires one additional connection option in the irrigation computer. Because the black phase cables are bundled in a community cable and therefore they always need exactly one connection option, regardless of the number. In the professional sector, this type of irrigation computer is used almost exclusively. Another type of irrigation computer, in which the valve is permanently integrated in the irrigation computer and the water flows through, is dealt with in a second blog post of sprinkler timers.

The number of valves that can be connected and thus the number of irrigation sectors that are possible with the computer is the basic key figure when selecting the computer. In addition, there are a handful of other fundamental differences that also explain the large number of different irrigation computer models and types from the major suppliers like Hunter, Rain Bird, Orbit or Racchio.

Indoors or outdoors

Irrigation computers are offered that are only suitable for indoor use and those that can be used outdoors. The former are a cheaper alternative if you can mount the computer in the basement or technical room, for example, otherwise you need the wind and weather-protected outdoor model in any case. In outdoor models, the transformer is housed in the irrigation computer, in indoor models it hangs outside. With Hunter and Rain Bird, the indoor models can be recognized by an “i” in the type designation.

Electricity or battery operated

Irrigation computers for valve control are usually powered by electricity, which means you need a connection to the power grid to be able to operate the computer. Hunter, Rain Bird and Orbit also offer battery-operated models in their range, Hunter also has a hybrid model that can be operated with both batteries and electricity. The battery-operated watering computers do not work with the normal 24 volt solenoid valves, but with 9 volt solenoid valves.

See blog post: Solenoid valves – which ones are there and how do they differ?

Fixed or flexibly expandable number of valve connections

Most of the models have a certain, specified number of connections, which means you can connect a maximum of this number of valves. Other models can be expanded in the modular system, e.g. you start with 12 connections and can then expand as required, e.g. in blocks of 6 up to a certain specified maximum number.

Web enabled or not

In addition to the usual, autonomously operating computers, WiFi-enabled computers are also available, which can be connected to the web via WiFi. On the one hand, this enables programming and operation via app and, on the other hand, it is also the basis for integrating irrigation into home automation. Additional services such as controlling the irrigation via local weather data received via the web are also offered, so that the web connection can also be used as a substitute for the use of sensors.

Hunter took a big step in this area in 2016 with the acquisition of the Australian company Hydrawise and bought a lot of expertise. Hydrawise was only founded in 2011 and specialized exclusively in the production of WiFi-enabled irrigation controllers and irrigation software. The result of this acquisition is the WiFi enabled Hunter HC Hydrawise range.

Rain Bird initially went a different route and did not offer its own WiFi-enabled models, but instead offered the option of making some of its models WiFi-enabled using an additional expansion module. The module is simply plugged into a pre-reserved slot. This option is still available and Rain Bird now also has models with a fixed WiFi connection in its range.

Orbit offers quite powerful web-enabled computers at a very attractive price and Racchio is the first choice for many users when it comes to web-enabled computers.

Extra models for self-sufficient installation in the valve box

Rain Bird, Hunter and Orbit also have a battery-operated, very space-saving, compact model on offer that is intended for direct attachment to the valves or in the valve box: The computer is housed in the valve box and controls from there – depending on the model or multiple valves. This is primarily a variant for more remote locations that are difficult to reach with electricity.

Below is an overview of the most important watering computers on the market from the point of view of a private user:

Good value irrigation computers

This computer are limited to the essential functions, i.e. they largely do without what is not absolutely necessary in favor of a lower price and also have a manageable number of outputs and no web access. This does not mean, however, that these would perform worse than the more expensive models for the requirements of normal operation. The models listed here are very solid irrigation computers.

The following sprinkler computer are offered in different variants, for example for 4, 6 or 8 valves. For the sake of simplicity and clarity, however, these model variants are not considered individually here and in the following, but are listed in the table under “Model variants”.

Tip: Always calculate a certain reserve with regard to the number of solenoid valves, so it is always better to buy one size larger. If you need 4 sectors according to your calculation, then it is better to buy the model to which you can connect 6 solenoid valves. This way you stay relaxed if you made a mistake in planning and still need one more sector, or if you want to expand the irrigation later.

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Web-connected irrigation computers

The following irrigation computers have a built-in WiFi connection and can therefore be controlled via mobile phone or desktop computer. They also offer additional web-based functions such as weather-dependent irrigation control.

Finally, a tip for all those who are interested in an open source irrigation computer with extensive customization options for both hardware and software.

Rain Bird and Hunter WiFi module

Below is a brief presentation of the expansion modules that can be used to make some of the Rain Bird irrigation computers or the Hunter X2 web-enabled.

Battery operated irrigation computers

Hunter offers the XC hybrid here, which is almost identical in construction to the X-Core, but also only works with a battery. The performance data is also the same as that of the X-Core. From Rain Bird there is the battery-controlled WP series. All of these models will only work with 9 volt DC solenoid valves.

Compact battery models for use in the valve box

Rain Bird, Orbit, Hunter and others also offer very small, handy, battery-operated computers with which the solenoid valves are controlled directly from the valve box. The Hunter Node and the Orbit battery operated controller are programmed directly on the device. The Rain Bird TBOS-BT cannot be programmed directly via the device. Instead, they can be programmed via a Bluetooth connection via a mobile phone app. A programming part is also available for the Rain Bird TBOS-BT if you prefer to use it for programming. Programming via Bluetooth connection also has the advantage that you do not have to open the valve box to make program changes and that you can start irrigation from your cell phone (if it is within Bluetooth range of the water computer). The Galcon 6100 series can be programmed directly on the device or via a mobile app with Bluetooth.

The Rain Bird TBOS-BT is placed in the valve box and can control 1 to 6 valves depending on the model. The Hunter Node and the Galcon 6100 can also control 1 to 6 valves and can be mounted directly onto a solenoid valve, as well as The Orbit battery operated controller which can control 4 valves.