Upper vs Lower Ventilation (again).
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  1. #1
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    Default Upper vs Lower Ventilation (again).

    Ok - I've just read a post in which somebody is blaming the lack of an upper entrance for his colony losses ... so I thought this might be a good opportunity to revisit the old chestnut of which is best during winter - 'upper or lower ventilation' ?

    Warm, moist air rises - obvious isn't it ? Or is it ... ?

    Now although perfectly true as a statement, there are two things inherently unsatisfactory about how this warm moist air comes into being: the first is that air becomes 'moist' by the process of evaporation of liquid water into water vapour - and as anyone who's sat in a boat out at sea wearing wet clothes will tell you - evaporation causes chilling, to such an extent that it often results in hypothermia.

    So, from evaporation 'moist air' is generated - only that air isn't warm. Quite the contrary - it's actually quite cold - and a parcel of cold air, being denser than the air around it, will initially descend, and NOT ascend.
    Should it descend and encounter a substantial opening to the atmosphere, it will quite literally 'fall out of the hive' - but if such an opening isn't present, then condensation will occur upon the cold floor surface (evidence for which is often seen as black mould).

    The second issue is that eventually, these molecules of cold air will begin to be warmed to whatever the ambient temperature happens to be in that part of the hive. At this point - the water vapour component of the air, having a lighter molecular weight than the air which holds it, will indeed begin to rise - but only at the cost of reducing the local internal temperature of the beehive.

    The above may go some way to explain how BOTH upper and lower ventilation can remove water vapour from a beehive - that is, the moist air initially descends, and only later does it begin to ascend. However, from a temperature conservation point-of-view, adequate bottom ventilation is clearly to be preferred.
    Interestingly - with those using conventional hives - Europeans tend to favour bottom ventilation in winter, whereas Americans appear to prefer upper ventilation.


    To flesh this issue out a little more:

    Water has a molecular weight of around 18, whereas the gas nitrogen has a molecular weight of 28, and oxygen 32 - therefore molecules of water vapour are significantly lighter than those of dry air, and so will rise - which of course is why we see clouds high up there in the sky. And, as a one-time chemist, I used to hold the simplistic view that moist air rises ... and that was the end of the matter.

    However, I was to discover a paper by Harry D. Tiemann, 'Kiln Drying of Wood for Airplanes', 1919. Now Tiemann was no slouch when it came to chemistry - a subject he even taught for a while - and so would have been well aware of the molecular weight argument. However, on page 15 of his paper (Bulletin 509 : The Theory of Kiln Drying), he writes:

    " ... evaporation is of itself a cooling operation, and calculation shows that the effect of evaporation is to increase the density of the humid air in spite of the fact that more vapor has therefore been added. [my emphasis] This means that there is a natural tendency of the air to descend as it passes through the lumber, particularly when rapid drying is taking place. The arrangement of the pile of lumber and the kiln, therefore, should be such as not to oppose but to assist the natural gravity tendency. [again, my emphasis] Success or failure sometimes hinge on this point. Extensive observations under all kind of conditions and in all kinds of kilns have shown that this theory of the downward tendency of the air through the pile is the correct principle."
    Tiemann's principles went on to form the basis of the Oregon kiln-drying industry which today has an annual turnover of many millions of dollars, and yet - ironically - American beekeepers have yet to embrace these same principles in the removal of humidity from within their beehives.

    Perhaps this is the point at which I say ... "Tin Hat ON".
    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

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  3. #2
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    Default Re: Upper vs Lower Ventilation (again).

    Quote Originally Posted by little_john View Post
    Ok ........

    Tiemann's principles went on to form the basis of the Oregon kiln-drying industry which today has an annual turnover of many millions of dollars, and yet - ironically - American beekeepers have yet to embrace these same principles in the removal of humidity from within their beehives.

    Perhaps this is the point at which I say ... "Tin Hat ON".
    LJ
    Donno, LJ.

    This entire evaporation context formed around kiln wood drying is not exactly applicable, I don't think.
    After all, in the kiln there is no such thing as significant air gradients from very warm to very cold.
    They dry wood in consistently warm and dry conditions, I would guess.

    Meanwhile, the kiln temperature/moisture context is so different from natural air/moisture movements generated by a warm bodied and breathing organism in cold conditions (bee cluster is essentially that - warm bodied, breathing organism).

    Italian scientist Count Lorenzo Romano Amedeo Carlo Avogadro (1776-1856), who hypothesized that equal volumes of gasses at the same temperature and pressure contain equal numbers of molecules.

    by 1860 Avogadro’s law was a bedrock of chemistry as it still is.
    Here is a popular read explaining how it all works out.
    https://www.washingtonpost.com/news/...=.e5a1ec338843

    And so indeed, humid air is lighter than dry air given the constant temperature and pressure because a molecule of water (H2O) is lighter than a molecule of oxygen (O2) or a molecule of nitrogen (N2).

    Granted, the temperatures of the humid air exhaust are changing from warm to cool rapidly, this moist bee exhaust still has plenty of buoyancy in it to try escaping upwards if possible (at first). Then, as the air cools further AND gaseous water condenses into liquid water due to hitting 100% humidity cut-off (water molecules will congregate into floating water caplets, that is), the air then will drop down.

    And so, removing the moisture via upper entrances is very efficient at moisture removal in particular and it works exactly as advertised.
    My personal issue with it is that upper entrances are very inefficient in winter store usage (bees burn through the honey so to compensate the excessive ventilation).
    Meanwhile, upper entrance ventilation is not even necessary to achieve adequate ventilation.
    I don't have upper entrance ventilation and don't have moisture issues either (and don't leave 80 pounds of honey per a hive either, as unnecessary).
    Last edited by GregV; 12-24-2018 at 05:48 PM.
    Former "smoker boy". Classic, square 12 frame Dadants >> Long hive/Short frame/chemical-free experimentations.

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    Default Re: Upper vs Lower Ventilation (again).

    Lj , is this moisture in warm air not created by the warmth and breathing of the cluster and does it not rise to the top and sometimes meet with the cold inner cover and then condense this moisture onto the cold surface of the inner cover or migratory lid. I often see this condensation on my migratory lids especially on strong hives and for this reason use insulation under the migratory cover in the winter and above the inner cover on the standard lids. Now that moisture has not really cooled the air but cooled the bees that are exhaling and if it did cool the air and descend it would go out of my bottom entrances but still I have condensation at the top of my hives.
    Johno

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    Default Re: Upper vs Lower Ventilation (again).

    Merry Christmas to everyone.

    Quote Originally Posted by little_john View Post
    Ok - I've just read a post in which somebody is blaming the lack of an upper entrance for his colony losses ... so I thought this might be a good opportunity to revisit the old chestnut of which is best during winter - 'upper or lower ventilation' ?

    However, from a temperature conservation point-of-view, adequate bottom ventilation is clearly to be preferred.
    ?????????

    Choke the bottom entrance down and use a small upper entrance to get a gentle flow of air. My bottom entrance is 3/8 by 1 jnch wide and upper entrance is 3/4 round hole in a feed shim and quilt box. Internal temp of hive at top is 20-30F warmer than ambient. 2 inch of styrofoam on perimeters. One can slightly crack open the front door and slightly open a second floor window of a house to get a gently air flow or open them wide.

    In cold temps 3/4 round hole will nearly frost over, with a cone of frost, from exiting moisture and top 1/2 inch of shavings is moist/ice crystals. Moisture is rising and exiting.

    This works so well, I am hesitant to try bottom ventilation.
    Zone 3b. If you always do what you always did, you'll always get what you always got!

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    Default Re: Upper vs Lower Ventilation (again).

    Quote Originally Posted by mgolden View Post
    In cold temps 3/4 round hole will nearly frost over, with a cone of frost, from exiting moisture and top 1/2 inch of shavings is moist/ice crystals. Moisture is rising and exiting.
    Sure - but the water vapour isn't exiting on it's own - it's exiting along with the air which supports it, And for that air to rise it must be warmer than the air which surrounds it - and so where does the energy to warm that air come from, if not from within the beehive itself ?

    Which is why I said " ... from a temperature conservation point-of-view, adequate bottom ventilation is clearly to be preferred."

    This works so well, I am hesitant to try bottom ventilation.
    Then don't - I'm not trying to sell a methodology here, just trying (hopefully) to establish some kind of understanding of the possible mechanisms involved.
    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

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    Default Re: Upper vs Lower Ventilation (again).

    Bottom ventilation also results in heat loss, probably air convection within the hive. This would be so particularly with front and rear lower entrance. Is it more less than a modest upward flow?????

    At the end of the day, it is better to have an interior temp of 4-8C to minimize bee activity and honey consumption.

    A study of the two methods of ventilation would be an interesting read. Does one method or the other result in a drier interior? Nosema problems are less with a drier interior. I haven't used fumagillin in last 7 years and no Nosema apis problems. Does one or the method result in a more optimized interior temperature?
    Last edited by mgolden; 12-26-2018 at 10:58 AM. Reason: meant to say apis
    Zone 3b. If you always do what you always did, you'll always get what you always got!

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    Default Re: Upper vs Lower Ventilation (again).

    Quote Originally Posted by johno View Post
    I often see this condensation on my migratory lids especially on strong hives and for this reason use insulation under the migratory cover in the winter and above the inner cover on the standard lids.
    Hi Johno - hope you had a good festive ...

    You raise a good point - I've experienced exactly the same myself.

    I see the bottom vs top ventilation issue as having two components - the dynamics involved, and any explanation of them. And of course it may well be that the explanation I've offered is partially - or even completely - incorrect.

    Having said that, I'm now going to steal a phrase from your Founding Fathers ...

    I see two "truths which are self-evident" - the first being that in those countries where bottom ventilation during winter is practiced, this is extremely successful - otherwise they wouldn't continue to use it (!)

    And so I've tried to compile an explanation for how upper AND lower ventilation can BOTH work - perhaps I haven't been entirely successful, but I'd like to think this was a reasonable effort.

    A second self-evident truth is that Tiemann's methodology DOES work. Perhaps it doesn't function strictly according to his theory - but it certainly works in practice, and a major industry has been founded based upon this methodology, and which has continued to work right up to the present day - using exactly the same techniques, whether these be theoretically correct or not.

    The principle reason I've been focussing upon Tiemann's methods is that his kilns appear to me to be a fairly close analogue to that of the 'hive sealed at top and sides, with bottom ventilation'. Sure, his kilns are designed to extract moisture from within timber (lumber), but it is the method of drainage - which is only ever at the bottom - which I find a compelling feature.

    It might be worth mentioning here that when Tiemann first proposed his ideas, they were rejected out of hand as being completely unworkable. (perhaps his employers had fixed thinking related to other forms of moisture-removing structures - such as those for hops - which vent at their tops ?)(*) It was only after Tiemann went ahead and built a kiln to his own design (a shed, heavily insulated at both top and sides, draining via the bottom), and duly demonstrated that his principles worked, that his employers finally began to listen to him.

    Some of Tiemann's principles are truly counter-intuitive - perhaps that was the root of the problem of acceptance ? These include injecting steam into the kiln, for at first sight it does seems crazy to be adding even more moisture when the object of the exercise is to actually remove moisture ...

    But isn't this exactly what happens when bees exhale during winter ? One major component of their metabolism is water vapour, and that is added to air which already contains water vapour - just as with Tiemann's kilns. Any heat energy which the bees' water vapour contains is analogous (perhaps ?) to the heat provided by Tiemann's steam injection.

    It often occurs to me that one of the huge problems we humans face when investigating issues related to gases is their non-visibility. With a few notable exceptions, gases in general are invisible, and although in reality we move around within a soup of gaseous molecules, we tend to view the atmosphere - especially that which exists immediately before our eyes - are being just so much 'empty space'.

    It's only occasionally that we get to experience visual evidence of gases becoming visible. The most common of these is during Winter when our exhaled breath often becomes visible at it encounters cold air.

    Now bearing in mind that the molecular weight (and thus it's gravitational attraction) of a molecule of water doesn't change - whether it happens to be a molecule of ice, water, water vapour or steam - the only thing which changes is it's physical state. And so when we exhale our warm breath on a cold frosty Winter morning, what happens to those - now visible - water molecules ?

    At the moment I'm waiting for a really cold day in order to check this, but from memory this visible 'cloud' appears to hang in the air (with neutral buoyancy, as it were) until it dissipates. It appears to neither ascend or descend with much enthusiasm.
    This phenomenon is of course simply a case of a sudden drop to dew-point of heavily moisture-laden exhaled air, which causes a change of state of the (gaseous) water vapour component into molecules of liquid water which remain more-or-less suspended in the air which contains them - any tendency for them to rise (due to their molecular weight being less than that of both nitrogen and oxygen) being countered by the gravitational pull of the Earth.

    There is also gravitational attraction between the molecules themselves, and so they will gradually begin to coalesce into much larger entities which - as we see in the case of light drizzle - eventually become sufficiently large to fall free from the atmosphere which, until then, had been supporting them.

    Could this then be a better explanation for how bottom ventilation works so effectively ... ?

    Although we normally think of moist air rising - as with clouds in the sky - this isn't always the case, as can be seen in the following photograph:



    Indeed, whenever we witness the existence of early-morning dew, this also confirms that moisture from the air has descended - at least until such time as it is warmed by the sun.
    'best
    LJ

    (*)"Perhaps the term 'kiln drying' has an unfortunate association with lime or pottery or brick kilns, in which the material is baked."
    The Kiln Drying of Woods for Airplanes - National Advisory Comittee for Aeronautics, 1920
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

  9. #8
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    Default Re: Upper vs Lower Ventilation (again).

    Lj it does not really matter where the moist air eventually goes to as long as it does not go to a cold surface above the bees and then condense and start dripping on the bees. Now after saying that I have reduced bottom entrances and small vents on a feeding shim which is under the insulation and still find a little condensation under the inner covers or under the insulation however I am sure that I would have more if I never had insulation.
    Johno

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    Default Re: Upper vs Lower Ventilation (again).

    I have a sheet of clear 4 mill plastic between the top bars and the insulated inner cover on all my hives and nucs. When the outer cover and the inner cover are removed from the colonies with solid bottom boards the only condensation is in the corners of the box and along the edge where the top and sides come together. There is only a little, and often bees are collecting it. The colonies with screened bottom boards usually have none.

    I quit using a top entrances/vents 40 years ago when I observed that colonies with only bottom entrances overwinter as well or better than those with upper entrances. Our temperatures are mild compared to what northern beekeepers have. Our lowest overnight temperature this year is 17F, and usually the daytime temps are mid 40s to low 50s.
    42 + years - 24 colonies - IPM disciple - Naturally Skeptic

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    Default Re: Upper vs Lower Ventilation (again).

    Quote Originally Posted by little_john View Post
    .....which causes a change of state of the (gaseous) water vapour component into molecules of liquid water which remain more-or-less suspended in the air which contains them - any tendency for them to rise (due to their molecular weight being less than that of both nitrogen and oxygen) being countered by the gravitational pull of the Earth.

    There is also gravitational attraction between the molecules themselves, and so they will gradually begin to coalesce into much larger entities which - as we see in the case of light drizzle - eventually become sufficiently large to fall free from the atmosphere which, until then, had been supporting them.

    .............

    Indeed, whenever we witness the existence of early-morning dew, this also confirms that moisture from the air has descended - at least until such time as it is warmed by the sun.
    'best
    LJ
    I am getting confused here....

    There are NO molecules of "(gaseous) water vapour" as opposed to "molecules of liquid water" (or "molecules of hard water", for consistency).
    There are only molecules of water that ever exist (a natural chemical compound that can exist in various physical states - three main states as documented).

    Molecules of water (when in gaseous state) can never be visible.
    For sure, I do not see them in my cube around me just as of this writing - and yet there are billions of water molecules floating around me; I breath lots of them out myself every minute.

    What is visible under certain conditions - liquid water caplets or hard water clumps, present in the air, and large enough to reflect light (so we can see them).
    For any object to be visible, the object must be large enough to reflect light (talking about even the tiniest water droplet still being thousands and millions times larger than a single water molecule).
    So we only can observe liquid or hard water conglomerates large enough to reflect light (but never gaseous water).

    Still, conglomerates of liquid or hard water very commonly are small enough to stay up in the atmosphere indefinitely and virtually never fall down (those darn, high-altitude clouds are very stubborn at hanging up there).
    Former "smoker boy". Classic, square 12 frame Dadants >> Long hive/Short frame/chemical-free experimentations.

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    Default Re: Upper vs Lower Ventilation (again).

    Bees move air where they want it in warm weather anyone check to see if there is (bee supplied) air movement around a cluster?

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    Default Re: Upper vs Lower Ventilation (again).

    It is the cold weather we worry about, not sure how much air clustered bees move but any cold moisture dripping onto clustered bees spells disaster.

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    Default Re: Upper vs Lower Ventilation (again).

    Hmm, would you rather wear a dry sweater in a 20F room, or a wet sweater in a 40F room. The dry sweater wins every time. I simply do not understand the concept that you need to hold the heat, and thus any moisture, in the hive. Mostly because I know that the bees are not trying to heat the hive in the first place. Whether you use an upper entrance, a screened bottom board, or just crack the telescoping top a little, some air flow is necessary for the health of the hive.

    BTW, high altitude clouds, i. e., cirrus clouds, are composed of ice crystals. That is why they are able to get that wispy feathery look.
    Thankfully, the bees are smarter than I am. They are doing well, in spite of my efforts to help them.

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    Default Re: Upper vs Lower Ventilation (again).

    Quote Originally Posted by JWPalmer View Post
    Hmm, would you rather wear a dry sweater in a 20F room, or a wet sweater in a 40F room.
    there is a way to not have a wet sweater and still get the warmer room; beekeepers making poor decisions create the wet sweater in a colder room.

    the cluster of bees will generate warm air and this air will form a localized bubble of warm air around the cluster so long as there are not drafts and currents which disrupt the bubble of localized environment. when extra vents are made or wind is able to enter the hive without diffusing it will create turbulence which reduces this bubble of safely around the cluster. when that bubble becomes reduced, colder air gets closer to the moist air the bees are exhaling and increasing the likelihood that condensation will form closer to the bees. warm air can keep more moisture suspended in solution before it falls out, drafts increase cold air and you lose the control of where the moisture will fall out. most people fight this ghost of condensation and do more damage than good. the bees require more food and if it too cold they may not be able to reach that food on marginal days that a better insulated hive with no heat escaping out can. a well sealed, proper fitting hive, with no drafts and a insulated top cover will keep condensation away from the cluster. for insurance, a hive that is then tilted back and small holes drilled in bottom to release the water which may collect is a logical way to deal with the ghosts beekeepers have created while reducing the stress of the colony. most people already tilt their hive and have insulated top covers. they are so close to helping the bees but then drill holes and allow precious heat(it is not free and comes at an expense) to escape and make it difficult for bees to deal with condensation. many of these colonies are dealing with other stress and eventually they add up to death. minimize as much stress as possible, do not create it. i think people are unable to understand they are doing more damage then good with ventilation, with enough people speaking out about it, maybe someone will explain it in a way which makes sense to them. i think people feeding their bees syrup too late and not switching to dry sugar when below 50f makes it next to impossible to deal with the condensation.

    there does not have to be a wet sweater in the hive, the large majority of beekeepers fabricate this condition from poor decisions and their bees suffer.

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    Default Re: Upper vs Lower Ventilation (again).

    How big is this "bubble" of warm air supposed to be and what data do you have to prove it even exists? The presentation I attended on wintering bees had some hard data using thermal imaging that showed the that on a 0F day, the temps just outside the cluster were just a few degrees above ambient. In this case, the core was right at 90F and the outside of the cluster around 40. Not but inches away, the air inside the hive was 17. Though slightly warmer above the cluster. Don't remember the exact number. One thing is certain though, humid air is more thermally conductive than dry air so a moist hive environment is more likely to pull the heat away from the bees than to help them retain it. Keep in mind, we are not talking a drafty hive, just one in which there is a means for humidity to escape, before it condenses and rains on the bees.
    Thankfully, the bees are smarter than I am. They are doing well, in spite of my efforts to help them.

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    Default Re: Upper vs Lower Ventilation (again).

    Quote Originally Posted by GregV View Post
    I am getting confused here....

    There are NO molecules of "(gaseous) water vapour" as opposed to "molecules of liquid water" (or "molecules of hard water", for consistency).
    There are only molecules of water that ever exist (a natural chemical compound that can exist in various physical states - three main states as documented).

    Molecules of water (when in gaseous state) can never be visible.
    Water has FOUR states, not three: solid, liquid, gas and vapour. Solid being ice (of course); liquid being the water we're so familiar with; and steam being an invisible gas. However, there is also 'vapour', which is perhaps best thought of as a being 'like a gas, but at the wrong temperature'.

    Water vapour exists at a temperature significantly below that at which steam would be formed, yet is neither a liquid (with molecules in intimate contact with each other), or solid (with molecules forming a crystalline lattice) and yet possesses many of the characteristics of a gas - that is, it's molecules are spread far apart and thus will readily mix with 'true' gases.

    Perhaps it's easiest to understand the nature of water vapour if one considers electron shells: with ice these electrons are responsible for binding the water molecules very tightly together; with liquid water the binding is much looser, yet still exists - as can be seen with surface tension/formation of a meniscus etc.; in it's vapour state however, the molecules are spread so far apart that not even the outermost electron shells of it's component atoms can interact with other water vapour molecules - so that there's no longer any binding present (such as surface tension - 'cause there's no surface for it's existence), not even when those molecules become momentarily visible when exhaling on a frosty day.

    In it's vapour state then, water acts for-all-intents-and-purposes 'as if' it were a gas, yet at an absurdly low temperature when compared with that required to form steam - which is why I used phrases such as "(gaseous) water vapour" when describing it.
    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

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    Default Re: Upper vs Lower Ventilation (again).

    Here is a paragraph or two from Dave Cushman's site. He explains why he is a believer in a well insulated hive top but no ventilation. Air and moisture exchange is at the vented bottom of the hives.

    http://www.dave-cushman.net/bee/ventilation.html

    I have been very successful with a heavy top insulation in the form of a 5" thick shavins insulation box that does provide a slow exit of the moist air atop of the cluster. Some heat is lost in the form of sensible heat and also the latent heat in the gaseous water vapor.

    Because of the pure physics of the issue as well as the knowledge that the sealed, insulated top indeed works very well in thousands of cold European country hives, I have decided to try it with 6 hives. I have from 3 to 4 inches of styrofoam blocks covering the top of the hives and no top vent.

    If I am happy with the setup come spring, I will appreciate how much easier it is than dealing with the shavings box tops. Not much of a test yet as it has only been down to a few degs below 0 F. yet and two and a half months to go! We usually hit close to 40 below but have not got there for the last few years.
    Frank

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    Default Re: Upper vs Lower Ventilation (again).

    When I chose the thread title "Upper vs Lower Ventilation" - the 'versus' was intended to refer to the underlying mechanism involved, as upper ventilation is easy enough to understand, albeit with some loss of heat as warm air will always accompany the moisture - no matter how minimal that air movement is. But - the mechanism of ventilation when this occurs in a downward direction is far less clear.

    So, for example - the following web-pages sing the praises of bottom ventilation:
    http://www.dave-cushman.net/bee/kenhomf.html
    http://www.dave-cushman.net/bee/open_mesh_floors.html
    http://www.dave-cushman.net/bee/ventilation.html

    ... but there's no convincing explanation there of HOW this works. The last link does contain a rather optimistic theory involving a proposed convection current within the hive's interior, resulting in passive gaseous exchange across the OMF by diffusion. A convection current might be plausible in a more-or-less empty box, but it's hard to imagine this happening within a box crammed full of combs with bees upon them - and taking place during Winter.
    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

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    Default Re: Upper vs Lower Ventilation (again).

    all heat sources produce a gradient area around them as they try and reach homeostasis with environment. i do not know the temperature of the cluster but based on what i have observed i imagine this gradient is still able to maintain a warm enough temperature that the moisture does not fall out of solution for about 4+ inches. this is because the heat rises and not able to escape. i image without a sealed upper environment, this gradient would be less than 1/2" from cluster temperature to ambient(like upper ventilation creates). reading your full response, looks like your presentation suggested 1", i will defer to their testing.

    one of my main points are, that beekeepers can manage the temperature in a way without upper ventilation successfully and most are just one step away from doing it. there is zero threat of condensation forming close enough to the bees that it drips on them should they follow the advice i offered; i think others have shared something similar.

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    Default Re: Upper vs Lower Ventilation (again).

    Indeed, my understanding is that most of the European poly hives utilize a screened bottom board that remains open year round. I do not advocate that a top vent is required, just that some form of ventilation is needed. Only 4 of my 16 have a top entrance but all are on SBB, most have an insert in place, but not all, and one has both a top entrance and no insert. Hives are bone dry and there are no dead bees piling up on the bottom boards. The idea of puposely trapping this humidity in the hive and then Rube Goldberging a way to deal with it is beyond hysterical. A dry hive is a happy hive.
    Thankfully, the bees are smarter than I am. They are doing well, in spite of my efforts to help them.

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