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Author Topic: Top vs Bottom ?  (Read 21321 times)

Offline BlueBee

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Top vs Bottom ?
« on: December 06, 2012, 08:30:55 pm »
Anybody tired of talking about insulation?  How about another much loved subject among bee keepers; ventilation.  Surely beeks can reach a common ground on top vs bottom ventilation?  Yes?  No?

Yes, I know this has been brought up lots of times before but we’re not suppose to drag out old threads to append new observations, so I thought I would start a new tread on this topic. 

I’m running hives and nucs with a variety of configurations this winter just to observe and learn.  One thing that has really given me some new insight into winter behavior is the use of a plastic sheet/foil for an inner cover.  Now I can watch the bees and the hive environment (temp, humidity, condensation, mold) all winter long without really disturbing the bees (except of course to throw in some more honey balls over the holidays  ;)).

So here’s a couple photos from two hives.  The first photo is from a hive with only a top entrance.  Note, no condensation whatsoever.  This design was totally dry and mold free last season too.  The second photo is from a new hive with only a bottom entrance.  Notice there is condensation in this hive, but the moisture is condensing to the sides of the cluster and I suspect won’t cause big problems; but time will tell.  That situation changes if you super a poly box with a box full of just honey.  Then the top box becomes cool and condensation occurs over the bees heads.  Kind of gets back into that Derekm hive tread..... :-\ 

Based on the activity of the bees in each hive and my IR temp sensor readings, the hive with the bottom only entrance is warmer.  That is not a surprise, but what does surprise me is the moisture seems to be under control at this point.






Thoughts? 
 

Offline RHBee

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Re: Top vs Bottom ?
« Reply #1 on: December 07, 2012, 12:17:58 am »
OK, I'll share my thoughts and conclusions on this subject. First, I believe that proper ventilation in the hive is what this all boils down to. Condensation any time is undesirable.  The fact that brood and bees get wet during the winter will lead to premature death.  The formation of mold is a secondary issue that I'm sure causes health issues for the bees. Secondly, a bottom entrance is needed to allow the bees to provide proper housekeeping.  Where I live upper entrances give the bees a greater area to protect and can thereby allow pests like the SHB and wax moth to invade easier. I think that the answer might be to use a solid inner cover that has spacers on the edges like popsicle sticks and also use SBB with a fine mesh. This would provide adequate air flow for the hive to remain dry but not allow unwanted pests to attack the colony from multiple directions.
These are only my thoughts and rationalizations of the issues as I understand  them.
Later,
Ray

Offline BlueBee

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Re: Top vs Bottom ?
« Reply #2 on: December 07, 2012, 12:43:50 am »
Thanks Ray.  Those are some good thoughts.  I don’t think there is such a thing as a right or wrong answer to the question of top vs bottom, so everybody should get an A in this exam.  I can see pros and cons in both.

Do you leave your screened bottom open all winter?

I’m experimenting with a little of everything this winter to see how the different configurations will work here. 

Offline Vance G

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Re: Top vs Bottom ?
« Reply #3 on: December 07, 2012, 12:54:18 am »
I like the plastic topping and I think I will now have another use for my roll of shrink wrap.  I have gone to an entrance bored in the top box right below the hand hold.  Since I put a 2 1/2 inch feeder rim on top box, that is not quite a top entrance as a nearly 9 inch area above the entrance can collect heat and the bees do indeed stay pretty toasty in this configuration.  Most of the bees seem to loaf hanging from the sound board innercover below the 1  1/2" styrofoam insulation once the cluster reaches the top and chews thru the mountain camp.  I top insulate and my hive wrap is supposed to be R 3.7  Mainly it is a fine windbreak and dead air space.  I close off the bottom entrance entirely for the cold months. 

Offline RHBee

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Re: Top vs Bottom ?
« Reply #4 on: December 07, 2012, 03:23:49 am »

Do you leave your screened bottom open all winter?


Right now I still have the full bottom SHB oil traps installed. The SHB can still be active at our current daytime temperatures and I don't want to take any chances. The high Sunday will be near 80degF. When and if we ever see consistent temps below 50degF I will be installing the SBB. I have the normal solid inner covers with a top entrance. I have modified them so that the entrance has fine mesh screen stapled over it and the regular oval hole is 4" in diameter so the bees can better access the bucket feeder holes.
Later,
Ray

Offline derekm

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Re: Top vs Bottom ?
« Reply #5 on: December 07, 2012, 08:34:59 am »
Can some one will give a typical size and placing for a top entrance, so i can put together an experiment to measure  heat loss?
If they increased energy bill for your home by a factor of 4.5 would you consider that cruel? If so why are you doing that to your bees?

Offline KD4MOJ

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Re: Top vs Bottom ?
« Reply #6 on: December 07, 2012, 09:32:30 am »
And to think I thought this subject was about something entirely different!  :-D

...DOUG
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Offline BlueBee

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Re: Top vs Bottom ?
« Reply #7 on: December 07, 2012, 11:32:27 am »
Size and place of a top entrance?

Well, it’s at the top. :-D  Sorry, I couldn’t resist.

For winter I reduce my top entrances down to 9mm x approx 50mm.  My top entrance is actually 60mm below the very top.

The bees have done great in those hives, but I've only been able to guess what the real temperature is inside.  At least with my clear plastic inner covers I can now get a better sense of how the bees are responding by observing how tight or loose the cluster is.

 

Offline T Beek

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Re: Top vs Bottom ?
« Reply #8 on: December 07, 2012, 02:41:14 pm »
Wonderful discussion.  We are waiting on BlueBees results for sure.  Seems there are a lot of experimenter Beeks trying to determine pro and con on this issue.  For my bees I'm convinced Top entrances have saved them from certain doom due to condensation.  That said I still use bottom enrances (set at smallest opening in winter) for all but 2 colonies (out of eight) this year.

My top entrances are simply a notch cut into the bottom of my inner covers, allowing the hive to expand w/ the bees.  

Those plastic sheets look interesting, I believe I've seen them used by some German Beeks with good success.  What are they?  Just plastic, any kind of plastic.  Very cool  8-)

Thanks for another great post BlueBee.
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Offline rober

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Re: Top vs Bottom ?
« Reply #9 on: December 07, 2012, 03:57:18 pm »
there is an example of plastic being used in this clip. these hives in general are interesting
www.youtube.com/watch?v=gKTvp1lupHY - Cached

Offline BlueBee

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Re: Top vs Bottom ?
« Reply #10 on: December 12, 2012, 01:57:23 am »
Rober, yep that is the video I got the idea from for my plastic sheet/foil inner cover.  Lots of good bee keeping nuggets in that video IMO.

Here’s a photo from earlier today of the 6 frame medium nuc that is configured with only a small bottom entrance (9mm x about 120mm).  This hive is definitely on the warmer side since the bees aren’t in a tight cluster.  They are just milling around inside the hive.  Temps look great in here, but the condensation is getting a little worse.  Still not like the rainy season in Florida, but clouds are forming.....



The interesting thing I see here is the condensation is off to the sides of the hive and away from the bees in the SINGLE DECKER nucs.  So if the condensation gets big enough to start raining down, at least it won’t fall on the bees.  The condensation in my double decker foam nucs is forming ABOVE the bees heads in the top box.  This is more likely to be a problem since at some point it will eventually rain down on the cluster.  If the volume of the foam is 2x the size of the cluster, the upper layer of combs are getting cold and looks to be cooler than the dew point inside the hive.

The hives with top entrances/vents basically look exactly like the earlier photo.  Bone dry and the bees in formal cluster.  They’re not moving around a whole lot, but they're not frozen stiff either.  Looks to be “sleeping” as Finski would say.

Offline PeeVee

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Re: Top vs Bottom ?
« Reply #11 on: December 13, 2012, 12:39:35 pm »
I like the idea you have shown with the plastic. Looks to be especially valuable to check on stores and/or emergency feeding.

I currently use both top and bottom entrance. Bottom in most hives are left open this year except for 1/4" screening as mouse guards. The top entrance it the usual opening in the inner cover.

Obviously if I plan on using the plastic I would need to modify how the inner cover is placed. Probably replace with a shim to incorporate an entrance and plastic.
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Offline tefer2

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Re: Top vs Bottom ?
« Reply #12 on: December 13, 2012, 12:59:28 pm »
The hives in the videos do not have a top entrance as far as I can tell. What they do have is an completely open bottom that the bees use for an entrance and to feed from the metal bowls. I always thought that the vis-queen covers trapped too much moisture. Maybe I'm wrong and the whole hive bottom open vents it out? She sure throws those hive bodies around, doesn't she.
By the way, all my inner covers have the notch down in winter. Bad experiences without a upper vent hole in winter for me.

Offline BlueBee

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Re: Top vs Bottom ?
« Reply #13 on: December 13, 2012, 01:11:46 pm »
For a hobbyist like myself, I really like the plastic inner cover.  It allows me to watch the bees and monitor how my different homemade hive designs are performing.  To date I haven’t had the need to feed any of my hives (except for the mating nucs in that other thread), but the plastic cover really works great for adding in some emergency food.  You can just peel it back a ways and put in food with minimum disturbance to the bees.

Good point Tefer, the plastic would interfere with vapor that would normally escape through an inner cover if that is your configuration.  The usefulness of the plastic inner cover is going to be dependent upon your hive venting design.

Offline BlueBee

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Re: Top vs Bottom ?
« Reply #14 on: December 13, 2012, 10:16:44 pm »
Interestingly, you may recall seeing the condensation in one of my mating nucs with a top entrance in that other thread.  Here is the photo again:



That seems like some pretty significant condensation and that is with a top entrance!  Go figure.  You can kind of imagine the convection currents in that photo as the warmer air rises above the bees and circulates to the edges of the box where the condensation is occurring. 

It is curious how I’ve got all this condensation in my mating nuc with with a top entrance but NONE in the full sized hive with a LOT more bees (beach ball sized clusters). :?  I'm not sure how to explain that at this point.   

Offline RHBee

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Re: Top vs Bottom ?
« Reply #15 on: December 25, 2012, 02:01:19 pm »
BlueBee, I have a question about top entrances. How do the bees clean out the hive debris and dead. I see a lot of experienced beekeepers who swear by top entrances I just don't understand how the bees deal with the housekeeping issues.
Later,
Ray

Offline little john

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Re: Top vs Bottom ?
« Reply #16 on: December 25, 2012, 05:30:27 pm »
Anybody tired of talking about insulation?  How about another much loved subject among bee keepers; ventilation.  Surely beeks can reach a common ground on top vs bottom ventilation?  Yes?  No?

I'd say no ...

My reasoning is that there may be 2 different mechanisms at work. Don't ask me exactly what they are - I just know that 2 conflicting dynamics are involved.

My evidence for saying this ? Observations.

Take clouds for example. They are evidence of suspended moisture, which has become visible by virtue of warm air containing that moisture rising up from sea-level and reaching the coldness of altitude. If that moisture should then become even colder, such as happens when the supporting air is forced to rise up over a mountain range, even more moisture will come out of suspension, and precipitate as rain (or snow if it's REALLY cold).

Ok - so far so good, no surprises there then.

Now lets take another scenario with this warm air containing moisture: when a belt of warm air (with it's suspended moisture) hits a cold front, then fog results, as the moisture comes out of suspension. Same principle, with humid air revealing the moisture it's carrying as a direct result of it suddenly becoming cold.

What we are witnessing are clouds of moisture occurring at high level, and clouds of moisture occurring at low level. One event taking place at high altitude (a dynamic which supports the upper entrance theory), but the other taking place near ground level (a dynamic supporting the bottom entrance theory).

Both events take place in the natural world - what is needed (imo) is for someone knowledgeable about such things to explain the conditions where one occurs and not the other - which may possibly go some way to solving this seemingly never-ending conundrum.

LJ
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Offline little john

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Re: Top vs Bottom ?
« Reply #17 on: December 25, 2012, 06:14:48 pm »
I think I've got it ...

It's all to do with the weight of the water, and the temperature (lifting capacity etc) of the air.

Modest concentrations of moisture can easily be lifted by warm air.

But dense concentrations of water vapour (heavy ...) held by not so warm air, will be unable to rise, and thus will stay close to the ground.

That's why this conundrum can never be solved - because 'it all depends'. Looks like both entrance locations will work, albeit under different conditions.

LJ

(any physicists in the house ?  confirmation of the above required)
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Offline Joe D

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Re: Top vs Bottom ?
« Reply #18 on: December 25, 2012, 10:58:53 pm »
I am still a newbee, last winter was my first and it was fairly warm.  I had SBB, bottom entrances, an inner cover with hole in middle and a gap on each side with a telescoping cover.  They did fine, I do have my hives on a slab with chain link fence around it with a small doorway on the south side, it also has a roof.  I put plastic sheeting on the west and north sides.  This fall I had some robbing and closed the entrances to about 3 in wide.  I also last year and this duct taped over the side holes in the inner cover except on the south side.  I am a lot farther south than a lot of you.  The hives normally don't get wet when it rains unless it blows pretty good.  Good luck to you.


Joe

Offline CapnChkn

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Re: Top vs Bottom ?
« Reply #19 on: December 26, 2012, 02:32:54 am »
Water vapor has a specific gravity of 0.6218.  That's 1 third lighter than air which has a specific gravity of 1.000.

http://www.engineeringtoolbox.com/specific-gravities-gases-d_334.html
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