· Michael Blair
A conventional controller runs the schedule it was given regardless of what the weather is doing. In a Middle Tennessee spring, that means watering through storms.
What they actually do
Weather-based controllers adjust run times using local forecast and historical evapotranspiration data, skipping cycles after rain and increasing them in heat.
The saving is real and comes mostly from not watering when it is unnecessary rather than from watering more efficiently.
Where the value is here
Middle Tennessee gets substantial spring and autumn rainfall interspersed with dry spells, which is exactly the pattern a fixed schedule handles worst.
A simple rain sensor achieves a good share of the benefit for far less money, and is worth fitting even to a conventional controller.
- A rain sensor is the cheapest large improvement
- Weather-based scheduling suits our variable rainfall
- Zone-by-zone soil and plant settings matter
- Remote access is genuinely useful for spotting a stuck valve
- Flow sensors catch leaks and broken heads automatically
They still need setting up properly
A smart controller with every zone left on default settings performs little better than a timer. Soil type, slope, plant type, head type and sun exposure all feed the calculation.
On Middle Tennessee clay, telling it the soil type is what enables the cycle-and-soak behaviour that prevents runoff.
Flow sensing
A flow sensor detects a broken head or a split line by noticing the zone is using more water than it should, and shuts it down.
On a large system that is the feature that pays for itself, because a broken head on a night cycle can run for hours unnoticed.