Keeping Them Cool Without Wasting Electricity

Here's a trick 'invented' here at New Avalon Farm...at least we'd never seen it anywhere else before we figured it out for ourselves. We're happy to share it with you, and we hope it helps.

In North Carolina's hot, sunny summers (as elsewhere), barn fans are an absolute necessity; horses need somewhere to cool down fast after a long stretch grazing out in the hot sun. But few things gall us more than hearing those fans running, consuming electricity, when there aren't any horses in the barn. The problem is particularly acute here at New Avalon, because we have arranged our pastures and gates in such a way that horses can get from the active pasture back to the barn (and vice versa) any time they want, so they are coming and going throughout the day. Leaving the barn fans running all day long, when the barn is most often empty, is something we just can't bring ourselves to do.

Fortunately our herd is pretty small, and so is our barn, so we don't need a huge fan; one three-footer on a rolling cart, aimed straight down the barn's alley, does the trick. A few years ago we wondered if such a fan couldn't be controlled by an inexpensive infrared-sensitive motion-sensing switch which would turn it on when horses enter the barn and turn if off again after they leave. We found such switches at the local big-box hardware store and experimented with wiring one into the circuit the fan is plugged into. And, sure enough, it works!

Here are a few tips if you want to try this yourself:

• Make sure the switch's rating exceeds the load drawn by all the electrical devices under its control. Don't burn your barn down with an overloaded switch!
• If you don't know what you're doing when it comes to electrical wiring, don't do it. Hire an electrician instead. Don't burn your barn down with faulty wiring!
• The trick is to mount the switch where it will 'see' the motion of the horses when they're in the barn. This won't work if the switch is mounted in a location that has it staring at the open barn door, because on hot sunny days the horses' body heat may be hidden in the infrared glare streaming in through the open door. This is a particular problem if there's a lot of sun-lit foliage beyond the open door, since green leaves reflect the sun's infrared light very efficiently. Another problem with aiming the switch at the open door is that these switches are most efficient when a heat source moves across their field of view, rather than toward or away from them. The solution to both problems turns out to be simple: mount the switch in the barn's rafters, looking straight down at the barn floor where the horses stand in the fan's breeze. The floor is always cooler than the horses, so the detector always 'sees' a high contrast between the horse's warm body and the cool floor, and in this orientation the horses are always moving across the detector's field of view, rather than toward or away from it.
• These switches have timers you can set so that after the specified interval with no motion detected (such as after the horses have left the barn) the switch turns the fan off. We find that a 10 minute interval is about right. Anything less than that can allow the fan to turn off while your horses are dozing motionless in its cooling breeze. But if you'd like to use a shorter interval in order to save more electricity, don't worry; horses seem to learn pretty quickly to move around a little to turn the fan back on if it shuts off before they're done with it.
• In the evening, or in the wintertime, or whenever the fan isn't needed, just turn it off with the fan's own switch...or if you're feeling clever, wire an on-off switch into the circuit (out of horses' reach, of course).
• Dogs, cats, chickens, and the like are generally too small to trigger the motion detector.
• Some motion-detecting switches work better than others. If at first you don't succeed, try another brand (generally speaking, the more expensive the better).
• Once a year, clean the accumulated dust off of the switch's lens for best performance.
• Your horses may startle the first time they enter the barn and the fan suddenly comes on, but they'll quickly get used to it. Once they do, they really seem to appreciate this amenity.