Owasso, OK Bee Farm Specializing in...
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Solar Ventilators

BeeCool Solar Ventilator

I’m not sure about where you live, but this little item generates quite a discussion in our club. I’m not one to jump on every band wagon that comes by, nor do I think I need every item in the major supply catalogs. I tend to keep asking myself “what do the bees want? How does it function in a wild bee hive out in the woods with no humans around fiddlin’ with it?”

So this item kind of breaks convention for me. Its definitely not natural, and I’ve never seen a fan installed on a tree. So how did I come to the conclusion to use it? By evaluating what the bees were doing, and considering if this device could help/supplement their efforts, and free up their time to go forage more. I didn’t come up with this one my own – a beekeeper friend of mine (Ken at Little Creek Bee Ranch – Inola, OK) pointed me to it and its part of the advertising of the ventilator – if the bees don’t have to spend time fanning at the front porch to cool the hive, and to create air circulation to dehydrate the collected nectar, then theoretically more bees are foraging – therefore increasing the honey crop. I couldn’t come up with a reasonable downside to it. So I bought two.

This picture was taken in late June, and the solar panel got cutoff in the picture, but you can see the vents under the top cover. Notice thats a single deep brood box with an excluder. Its a second year swarm catch dark colored queen.

The principle is simple – a solar panel, a bimetallic switch and a small fan. It functioned fine, and with 7 producing hives, the two with the fans produced 3 additional medium supers each over the rest. (all supers were fully drawn when placed on the hives) All 7 producing hives were in the same yard.This picture is of the purchased unit.

As the summer progressed there were several design issues that I thought should be improved. First, the fan was a 90mm unit and to move sufficient air it had to spin fast and therefore was loud. Fast spinning usually also means it pulls more current. With no capacitor or backup battery, the slightest shadow on the solar panel and the fan would stop. With no battery back up, when the sun goes down, the fan stops and everybody comes out on the front porch to beard. Around here during the summer it can be 9pm and 95 degrees outside the hive.

I built 5 using the box building techniques found elsewhere on this site, selected a SHF90 bimetallic switch from Graingers ($8), a 12 volt 120mm 9 blade fan with low current (.16ma) and low turn on voltage (7 volts), that produces 54 cfm at 12 volts (1300 rpm), a diode to prevent battery drain back through the solar panel when there is insufficient sunlight, and a rechargeable 12 volt battery like you find in exit signs and alarm systems. Worked like a charm just too late in the year to get much use from them this year. I’m making a few more changes for better efficiency – a single larger solar panel (45watt) that will run up to 20 fans and charge a deep cycle marine battery at the same time, and a small electronic circuit that allows me to adjust the cut on and cut off temperatures. A typical bimetallic switch has a 10 degree differential. So for the SHF90 switch it is actually 90/80 +- 10, so it could cut on as low as 80 or as high as 100. More than likely it will be within 3 degrees. If you happen to get one that is off by 3 degrees low, then it would cut on at 87 and off at 77 degrees. I don’t like that, I think the fan needs to come on around 90 and turn off at 85. This little electronic circuit is going to do the trick just fine, but I need to tweak it just a bit more before posting the circuit.

SHF90 Bimetallic snap disc switch

So there it is – I ran a test and my results surprised and pleased me, and so I’ll add more. The additional honey produced in one year on the hives that had the fans paid for the fans and then some. Works for me.