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Discussion Starter #1
I had a disaster when moving a couple nucs from FL to NY. One, an established nuc with lots of bees, overheated and died. This happened despite taking the advice of experienced beekeepers to make a screened top for the nuc. The nuc was transported inside the car, and we had AC to keep the cabin cool. Even worse, these were nucs moved from 5 frame boxes into 8 frame boxes. There was a screened vent hole on the bottom, and a screened entrance hole. The bees were packed tightly into the space between the frames and the screened top-- so tightly that the screen bulged out from them packing in. When I poured out the dead bees on the bottom, there was a pile a foot across and 4 or 5 inches thick. The other nuc did fine, but it was recently established and hadn't built up much yet.

Here's what I'm wondering: did they have too much ventilation? Last year I moved a couple nucs between NY and FL in 5 frame boxes with a small vent hole on the bottom, and a screened entrance. They did fine, and they were both packed with bees.
 

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Not enough air circulation. Didn't you hear them roaring? Confined bees will roar as they get too hot, trying to cool down by fanning off heat.

I thought you were going to carry them on a hitch off the back of you van. Did you stop at your daughter's?
 

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Discussion Starter #4
Not enough air circulation. Didn't you hear them roaring? Confined bees will roar as they get too hot, trying to cool down by fanning off heat.

I thought you were going to carry them on a hitch off the back of you van. Did you stop at your daughter's?
No, we drove straight through. The 8-frame box was inside the car, because everyone advised me that the AC would be better than the exterior air. The entire top was open screening, so I don't know how I could have given them much more air circulation. Plus a bottom vent hole and a screened entrance.

Here's why I think I may have given them too much ventilation, (besides the examples of smaller nuc boxes packed with bees that did fine with much less circulation.) I understand that bees can cool a hive, not just with moving air through it, but by evaporative conditioning. If your house has a window AC unit, it won't cool the house if all the windows and doors are open.

It's hard for me to figure out what went wrong. I put the contents of a packed 5 frame nuc in an 8 frame box with an open top. I've moved other packed 5 frame boxes without any problems over the same distance, one in August, but I was trying to do a better job. Disappointing.

On the good side, the hive I left up in the North Country did fine over the winter and is already brooding up well. I was astonished. I went to the bee meeting in Canton, and was sorry to have missed you.
 

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Not enough ventilation. Two things tell you it was not enough instead of too much. If you had too much ventilation the second would have died also, unless it was treated significantly different, even more so since it had less bees. The second thing is that bees can survive down to 42 degrees or so. Was the interior of your car ever that cold? If not, it was not too much ventilation.

too many bees to allow air to move through the cluster is sounds like. Was the box set where the bottom vent holes could allow air up through. You would get no real ventilation unless there was an air supply coming in the bottom, even with a screened top.

Live and learn.
 

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> did they have too much ventilation?

If you didn't have the AC running and the temps were in the 100s I'd say yes... but that wasn't the case... When they aren't free flying, though, they can't get water for cooling anyway...
 

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Discussion Starter #8
too many bees to allow air to move through the cluster is sounds like. Was the box set where the bottom vent holes could allow air up through. You would get no real ventilation unless there was an air supply coming in the bottom, even with a screened top.

Live and learn.
Yes, there was a 2&7/8" screened hole in the bottom, and I added a couple 3/4" rails to the bottom of these boxes, to keep the vent from being blocked.

It's a mystery to me, because I carried a colony just as dense the same distance, and it had no problems, despite being in a 5 frame box with a small bottom vent and a screened entrance. The colony that died had much more ventilation, in a larger box.
 

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Sorry to hear about losing the nuc. I can imagine it must have been very disappointing to open the hive and find nothing but dead bees.

"There was a screened vent hole on the bottom, and a screened entrance hole."

How big were these two holes? Even though the entire top of the hive was screened (and persumably open and not blocked by external objects), they would need more than just an open/screened top to get a good crossflow of air to exhaust heat from the hive. In other words, it doesn't matter how big the outlet is if the inlet is too small.

"The bees were packed tightly into the space between the frames and the screened top-- so tightly that the screen bulged out from them packing in."

If I am visualizing this correctly, if the bees were packed together tightly, they wouldn't have enough room to move their wings to move air through the hive.

The couple of times I have moved bees more than just a few miles, I have been surprised by how much heat they produce. I would now a move a hive a long distance (more than a ~60 minute drive) with both a screened bottom and a screened top, in addition to running the air conditioner.
 

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Discussion Starter #11
>The colony that died had much more ventilation

Keep in mind, that can be a problem if the temperature outside the hive is hot. What they need is enough ventilation, not too much or too little...
They were in an air-conditioned car.

This is confusing to me, as I've moved densely populated nucs the same distance without any problem, and they had much less ventilation. I'm not sure what to do in the future. Should I revert to my five frame nucs with modest ventilation? Should I go with screened tops and bottoms? I guess one thing I can do is only move recently-started nucs, so there aren't a lot of bees. But last August I moved a fairly good-sized swarm in a 5 frame nuc without problems.

Shinbone, the bottom vent hole was 2&7/8" and the entrance was one of those Kelley discs.
 

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What cools a hive is evaporation. The latent heat of water as it evaporates is orders of magnitude greater than dry air.
Moving air, absent water to evaporate into the stream of air, has virtually no capacity to carry off heat.

The air conditioning killed them because it dried the humidity in the air to zero (and any free moisture in the nuc). This makes us cool, because we evaporate water from our bodies through sweat into the dry air. We slurp down "designer water" to replace the losses. Bees don't sweat, and must carry surface water back to the hive to evaporate.

You could of misted them, or left a damp cloth in the box. They would have been okay with access to moisture.
 

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Just to provide some "back of envelope" numbers to the issue of water and air movement and overheating.

A 8 frame deep has about 0.027 m3 of air volume.
Mass of air in the hive may equal something less than 30 grams -- 33 grams for empty box.
Raising 30 grams 7 degree C (ie from 90 F to lethal 110 F) requires approximately 0.84 kilojoules of energy. In other words if the hive unbalances by about 200 calories, it goes lethal.

The latent heat of water (2260 kjoule per kilogram) implies that the entire nuc box could draw off the excess energy by evaporation and return to the preferred brood temperature by evaporation of 0.37 ***grams*** of water. That is less than one-tenth of a teaspoon. Alternatively it could move a massive volume of air (about 2.5 x the volume of the box).


The effect of water's massive heat of enthalpy also account for the hideous lethal effects of moisture in the winter. The excess moisture draws warmth from the hive with greater efficiency than air leaking through the hive.
 

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Discussion Starter #15
You could of misted them, or left a damp cloth in the box. They would have been okay with access to moisture.
I'll do that next time-- sounds sensible. But I still don't understand why the swarm I carried from NY to FL in August, with the AC on high, didn't have any problems. On this spring trip, the AC was only on occasionally.
 
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