Heat Relief: Screen under your hive tops?

[FloridaGardener]

I am many others use screened bottom boards, so the bees will herd the beetles through the 1/8" mesh down on top of the West Beetle Trap below.  So 1/8" keeps out bees, but not SHB.

Re: top entrances
Cupolas...Ridge Vents...commercial cooking fans...
If my garage didn't have a venting fan it would be brutally hot. 
https://www.bobvila.com/articles/attic-ventilation/

I leave a small top entrance in an imirie shim, on big hive.  I have insulated lids with reflective tin. 
20 bees can either hang on the lid inside ... and fan out the rising hot air .... or cluster around and block the gap... as they choose...

https://www.bobvila.com/articles/attic-ventilation/

[Ben Framed]

Re: top entrances
Cupolas...Ridge Vents...commercial cooking fans...
If my garage didn't have a venting fan it would be brutally hot.
https://www.bobvila.com/articles/attic-ventilation/

FloridaGardener you have made a great point! HEAT rises. Cooler air falls. With the bees (air conditioning running), it would seem the cool air generated by their water cooling system would be more effective if the hotter upper air of the hive were allowed to escape? Tim Durham believes in venting. He is the lifetimer beekeeper that I learned it from by watching his videos.  Therefore the heat is not trapped, while the bees are generating cooler air via their water cooling system, The hotter air escapes. You have me thinking again; just when I had decided to go back to insulated tops once again lol. I can definitely see a major difference in bearding since I wedged the tops. So which way is the best? I do not know. Thanks for your post. It is definitely food for thought!

[Ben Framed]

Adding more complicated food for thought, In the house itself, we do have insulation in the ceiling between the attic and roof. Making it easier for our AC units to cool our dwelling place of the house. So there is another monkey wrench thrown in the gears to consider?..  lol
Adding: Your analysis of ridge vents really stand out irregardless of area, dwelling attic area or garage area, both areas are cooler than they would be even on the hottest days!!..

Thanks again..

[AR Beekeeper]

Beekeepers should stop thinking about bees cooling hives the way we cool our houses.  Bees don't intend to cool the air as we do with AC units, they intend to cool the comb.  They do this by evaporating water on the comb surface and at the entrance to cells, so we should remember pre AC days and a fan moving air over our skin.  Fanning helped some if we were in the sun, it worked better if we moved into the shade, and it worked best if we wiped our exposed skin with a damp cloth.

We can help our hives cool by reducing the effects of solar heat by painting them white, placing them in the shade, or using shade boards, or using insulation on tops/sides of the hive, using open mesh bottom boards and hive stands to elevate them, and having a water supply close by. 

Bees fanning comb that is outside the hive in the shade, can cool the surface of that comb using wing power, so why should we worry about the number of entrances to a hive?  Bees fanning at the entrance of a hive are moving the air through the hive and out of the entrance at a rate of 220 to 250 cubic feet per minute which is more than enough to remove the body heat of the bees that remain inside the hive along with the more humid air from evaporation of the water.  Do we really need to add openings at the hive top so that the heat can escape?

[FloridaGardener]

Maybe not, but it makes me feel better because I give them the option - provided it's a small opening. 

And when the hive boxes are 5 high and there's a QX at between box 3 and 4, I do notice a few - but certainly not all - bees enter at the top opening. Maybe it's a shortcut to offload nectar when the bottom boxes are traffic jammed.

[Michael Bush]

>I will try and find it and post it if i can.

I would like to see that study...

>why should we worry about the number of entrances to a hive?

According to Huber (Huber's New Observations, Bicentennial edition, page 461:

"5th Experiment:  Increase in openings decreased  ventilation.
We tried increasing the number of openings in the side of the box, but were not successful.  One of the two candles went out at the end of 8 minutes.  The other kept alight as long as the ventilator was in motion.  I had therefore not obtained a stronger current by multiplying the openings.
These experiments show that in a place with an opening only on one side, air can renew itself when there is some mechanical cause tending to displace it, and this seems to confirm our conjectures on the effect which the fanning of bees has on the hive."

[FloridaGardener]

'Tis true that with no a/c in my car, I can roll down the window on only the driver's side, and feel cooler.  One opening does allow sufficient ventilation.

Another thing that really helps keep it cool is to leave enough capped honey (in the out-cycling brood comb) to be 6-3/4" of insulation on top.  Rather like tinted windows. 
Of course...for me... that means I must unload half the super into a workbox, before I can lift it off the top of the stack...

[Ben Framed]

Again part of the beauty of beemaster is folks getting together as we are doing here, discussing a subject with each participating member bringing in fresh ideas and prospectives of points of view to the round-table. Together we strive to find what is reasonably best for our bees.

I don?t just create an opening on top. Actually my tops are flat solid pieces of Advantec. No lips, no divots. Just a solid board for a top. I have never had a top come off or blow off. 3/4 inch Advantech is pretty heavy. The quarter inch wedge gives ventilation along the entire width of the back, but also the two sides. From zero gap at the front and gap increasing wider as we finally reach the full quarter inch gap at the back. This gives a goodly amount of ventilation to theoretically give a slight vent of moving of inside atmosphere. Again I am not advocating others to do this, though I am still in the process myself of this experiment. (I have not placed the insulation boards back in my tops yet... 😊

All your thought are welcome and appreciated.

[Oldbeavo]

The research project that i read stated that the opening of the lid provided what they called vertical  chimney like draft. It is effective in cooling the hive.
But they spoke about the convection air currents created  by  the bees are thought to be horizontal across the brood frames.
The bees bring in water to cool are using the convection currents to cool.
On insulation, the 7/8 - 22mm wood of the hives has an R factor of 1.2, while 1 1/2" - 40mm of poystyrene is an R factor of 7.9.
There is also thought that the outside frame that is usually full of honey works as a heat sink to capture incoming heat or hold heat in cold weather to protect the brood.
,
.

[rast]

Perhaps the bearding bees had to return to guard duty with almost 3/4 of the top of the hive open.

[Ben Framed]

You seem off of the screens, Phillip, but for anyone who is curious, #8 screen doesn't stop SHB, although it does slow them down.  I saw one squeeze through a screened inner cover today.  It was tight, but the little bugger made it through before I could smash him.    I did get his friend though. 

Thanks Member, I used the #8  when I was making screen bottom boards for use with oil trays a couple years ago as recommended by Beemaster2 and Paus. This set up worked well as the bees were excluded from the oil trays by number 8 HWC. As you described, the number 8 allowed the SHB to go through to their doom. If I were to continue on, deciding to use top screens as discussed here, I would not use number 8 Hardware cloth, but regular metal window screen (aluminum). I have plenty of this screen left over from a home project here a few years ago. If I do not scrap this experiment and where to continue onward, the screen expense would only be an indirect expense.   

[yes2matt]

Philip why not just try it on one or two hives? It's not going to kill them.

My bet is they will have it 85% sealed by the end of the season, and 100% by next spring. But as long as you don't clean the screen, they'll have a good propolis envelope.

Sent from my SM-J737P using Tapatalk

[BeeMaster2]

Matt,
I use screen (window screen) tops in all of my hives. The bees normally only propolis the outer inch of the screen. They do sometimes add more each year. During winter months you can easily remove most of it just by moving the screen back and forth and most of if falls off if it is cold enough. I do have a few screens that I have not cleaned that only have a six inch hole in the middle. They were built up over many years.
Jim Altmiller

[Ben Framed]

Thanks Matt and Jim, the screens would not be needed in my area during winter as SHB are not a problem at my location during the winter months. Therefore I would remove them. The Temperature usually drops into the 20s f every year, many years into the teens Fahrenheit some days, so cleaning what buildup should be a cake walk. Up until now I have not added any top screens.

[paus]

My experience is the same as Jim's .  I also have started placing a cloth over the screen and putting shavings or sawdust about 1 1/2 inches deep , level full.  I leave it there all year as this is excellent insulation.  Sawdust is a better insulation but not as good for use in the smoker, in an emergency or just changing the sawdust.

[TheHoneyPump]

In all this discussion about cooling , what is lacking is consensus on what ambient temperature level would be considered hot enough to warrant doing anything at all?  What is hot? What is the number?

[Oldbeavo]

The temp that seems hot for us is somewhere in the 95F+ range but with low humidity. We try to have our bees in shade by 11 o'clock. our Eucalypts provide a dappled shade but it is comfortable.
95 degrees in Arizona or 95 degrees in Florida, i would think that the higher humidity would test the bee cooling system.
Our rule of thumb is to have water as close as possible, no further than 300 yards is ideal.