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“Attic” Ventilation

Bee Culture – July, 2006

by Walt Wright

There is a list in my files of what are called “five-percenters.” Those are considerations in hive management or design that make a small difference in a total honey production. They may contribute only one percent to total production potential, or they may well increase production more than ten percent. Since there is no convenient way for me to assess the merits of each, they are lumped into the five percent general classification. Collectively, those small items could make a significant difference in your “bottom line.” By attention to details when they are not a significant penalty in cost or time, the overall results increase honey production.

The “five percenters” are considerations that occupy an unnecessarily large percentage of workers in some unproductive activity. In this discussion, the diversion of workers to fanning and evacuation of air flow space are those not engaged in honey production. Beekeepers are accustomed to the bearding of bees off the landing board in hot weather, and generally consider that normal. It doesn’t have to be. Those bees that evacuate to the beard out front are those making air flow paths through the comb for ventilation cooling. More fanners inside move the cooling air through those channels. Those fanners that you see on the landing board are a small percentage of the workers diverted to hive cooling.

It is interesting to me that at the beginning of the main flow, landing board fanners appear automatically. That’s the way they have dried honey for eons. Old habits are hard to break. When sufficient ventilation is provided, those fanners are no longer engaged in that chore. They soon learn that circulating air out the entry is not required. No fanners in sight, or maybe just a few hardheads, slow on the uptake.

So, what is sufficient ventilation? Glad you asked. To get maximum airflow up through the stack the overflow of warm air at the top should slightly exceed the entry incoming capacity. Warm air rise will do the job. The entry on my bottom boards is about 11 square inches. That means at least that much cross section must be provided at the top. A little more is better to accommodate air expansion when warmed and any intake leaks at the bottom.

The typical inner cover from suppliers doesn’t come close to being adequate. Even those with a scooped out section in the edge will not permit enough flow to cool a summer colony. The vent port in the center of most, sized for a bee escape, restricts air flow too much. The considerations are different in the winter and summer. In the summer, hive cooling is the objective. In the winter, the concern is metabolic moisture condensing overhead. In either season the inner cover is a key player in the desired results. It is the affectionately called the “attic.”

A too-small space between the panel and the hive cover invite other creatures to move in. Those vermin that are shorter or thinner than the patrolling honeybee are exempt from ejection. Roaches, earwigs, ants and the like are free to set up housekeeping. Note that roaches feed on decaying wood. That’s like living in a deli. The center panel of the inner cover only has to bow the slightest amount to cause the bees to seal the crack with propolis. With nine frames in the top box, the vent is directly over the center top-bar.

For the above reasons, my inner covers are homemade. It is the affectionately called the “attic. Half inch plywood is cut to outer box dimensions and a three quarter strip is added top and bottom. Nails are driver through the strips and clinched for extra rigidity. A four inch square opening is cut in the center of the panel such that the diagonal points of the square provide upward flow from the maximum number of frames below. This provides approximately 16 square inches of opening for upward air flow. It was done freestyle, with a circular saw, without measurement. (not recommended for neatness).

When daytime temperatures get into the eighties, the front of the cover is propped up with a cross stick. A 5/8 to ¾ thick stick, cut to hive width, is placed about one third of the way from the front. The increasing side angle created, and the opening at the front will overflow warm air at the bottom board intake rate.

Note that this design is not suitable for winter use, as shown, without help. The large opening directly above the cluster permits condensate, forming on the underside of the cover to drip on the cluster. The bees can handle cold, but they can’t handle wet and cold. To use this model overwinter, the square vent port must be closed off and the assembly turned upside down. Newspaper can be layered both above and below the opening to good advantage. The newspaper adds insulation, and any condensate that forms can be absorbed by the paper. Note the notches, front and back, in the rim to vent moist air in the winter is below the panel.

This approach is not as good as their natural residence, but is better than abusing your bees. In the tree cavity, where the insulation (live wood) is greatest at the top of the cavity, warm air is trapped there. It might even warm the live wood slightly, reducing overhead condensation. This is mostly speculation, but if the condensate formed on the sidewalls of the cavity, the water could be recycled in late winter to thin honey. Man, in his infinite wisdom, provides the bees with less than suitable quarters, and vents the moisture overboard.

A few words of caution: Observation indicates that a hive can be too well ventilated in the spring. The colony housed in a “hot box” can fill cells to the uncapping depth, extend cell depth, fill the deeper cells, and cap the product in a very short time. Although my bees don’t do that as quickly, some areas of the country report completing a super in a week or so. That speed implies that that nectar driers are very efficient and that there is an abundant corps of wax makers. It is reported that wax makers need a temperature of at least 100 degrees F to secrete wax. If you set out to flush the hive with temps below that level, it would seem reasonable that you might handicap the wax makers.

In my management system, there is often four or five supers of uncapped honey/nectar early in the main flow. Wax workers are lagging the incoming nectar. In a couple seasons where capping supers seemed to be lagging excessively, some quality wax was added in the attic. Some of it was used, but of course it’s difficult to say where it went. Even without the supplemental wax, the wax makers will eventually catch up with the need. By flow end, the honey will be capped. The bees are quite proficient at apportioning the work force to get the job done. Or, it might be that seasonal warming pushes the temperature toward the range of wax making requirements when ventilated with ambient air. You will need to assess these considerations for your area. If you normally extract honey from completed supers, to recycle supers back on the hives in the same flow, it becomes more important. It may be necessary to increase ventilation air flow incrementally with ambient temperature warm-up.

The photos were taken on May 8, 2006. The main flow has been on for two weeks. There are several of their favorite sources available in the field, but it’s been an unusually rainy flow, so far, and they haven’t made much progress. There weren’t as many processors in the attic as expected. Most were in the two empties of drawn comb below. As work progresses into those empties, more would move to the attic.

I take full responsibility for the poor quality of the photos. Photographer, I’m not. The point-and-shoot, “el cheapo” camera that stays in the truck for the random shot that maybe of interest, was used for these pictures. It has a minimum focus distance of 3.3 feet. That doesn’t permit a close-up picture. When the excess countryside was cropped off, what was left is what you see.

The picture block is intended to show nectar processors collected in the attic and the lack of fanners at the entry. The upper left side of the block shows the cover upside-down between two hives. The inept photographer strikes again. Shadowed by the hive at the right, the bees collected on the underside of the cover are barely discernible. The spacer stick, propolized along its length on both sides came off with the cover. Sometimes, it stays with the attic.

At lower left of the picture block is the attic used for many years. In a strong flow, on a strong colony, the upper deck is often literally covered with nectar processors. They gather there to take advantage of the warm air overflow that helps in the drying of nectar. This picture is not representative of that situation. Time spent on the cover picture and finding a stable position for the step-up platform in rough terrain allowed most of the processors to retreat below. Not only inept but also slow.

A feature of the deeper upper deck not mentioned above is the accumulation of hive scrapings. When the attic is angled on removal such that corners jut out of removed boxes, a handy place is provided to wipe scrapings off the hive tool. The bees can retrieve any honey in the scraping, and you can harvest the residual wax accumulated when you want.

The right side of the photo block shows a fairly busy landing board. No fanners were seen. Most of the bees were coming and going, and only a couple of blurs are caught in flight.

I’m not proud of either the attic or the photos. But I did want to show a picture of the attic. If it’s true that a picture is worth a thousand words, then even a lousy picture might have some value. If I were starting over in beekeeping, a winter and a summer model would be designed. Changed out with the seasons, they would be better than commercial models available for either season. If you have a flair for innovation, have a go at it. The design goal for the summer model would be to get rid of the vent stick and provide enough air overflow. The design goals for the winter model are a little tougher. It would be nice to collect condensate that is accessible to the bees for recycling. I personally resist boring holes in new boxes to vent the moisture overboard. Nobody bores holes in the tree hollow. I won’t preempt your ingenuity by offering concepts that I have in mind. Your answer might be better.