Upper vs Lower Ventilation (again). - Page 3
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  1. #41
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    Default Re: Upper vs Lower Ventilation (again).

    Water vapor also condenses on cold surfaces. If the sides are colder than the top by design, the bulk of the condensation will happen there. The moisture will be out of the way but still available to the bees.

    Response to Michael Bush #31

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  3. #42
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    Default Re: Upper vs Lower Ventilation (again).

    Quote Originally Posted by logicallycompromised View Post
    Vance G
    that is an improvement over "upper ventilation" but will encourage an exchange of warm air at the expense of the bees because the vacuum formed by air entering and exiting the hive body; i.e. venturi is formed. this is extra stress that colonies may or may not be able to deal with. i consider all variables as the proverbial straw which may break the camels back.
    I have successfully employed this system for about six seasons. Works well.

  4. #43
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    Default Re: Upper vs Lower Ventilation (again).

    JWPalmer,
    i agree with all what you have said because it is logical; protein not just for brood and required in winter(mites compromised the last couple brood cycles which determine the winter bees health-sugar is not enough for long cold winters), mites absolutely need to be treated(fills the bucket of stress too much), smoke does add stress.

    i do not think it is possible to remove the high humidity from the hive; the best we can do is manage it. we need to ask why the humidity in the hive is much above ambient? feeding syrup late in the year below 50f provides one point source. not having a weatherproof hive also makes maters worse, to include vented bottoms; i have obsessed about this detail as well.

    i mentioned it previously, most beekeepers already tilt their hives and use a insulated cover. based one what i have observed and understand, this is all that is needed to keep the moisture which falls out of solution away from the bees. i offered the explanation that around the bees will be a localized environment, a bubble of warmer air which protects them from condensation; warmer air holds more moisture before it falls from solution. too much airflow through the hive will reduce this boundary layer and may place the condensation too close and possible onto the cluster.

    i request that moving forward, beekeepers not only call out the points they do not agree with but also provide their own explanation for what they believe the added upper ventilation provides the colony. i have offered some explanations as to what they believe based on reading threads but i am not certain.
    thank you for your time!

  5. #44
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    Default Re: Upper vs Lower Ventilation (again).

    Quote Originally Posted by Michael Bush View Post
    You can google it and you'll find there are thousands of meteorologists who would love to explain that moist air rises. But the obvious proof is rain and the water cycle.
    Which was exactly my viewpoint until I read about Tiemann. The difference is between the Natural World - which is a totally open system (and with abundant energy supplied by the sun) - and the interior of wood-drying kilns and beehives, which are for-all-intents-and-purposes closed systems.

    I'm suggesting that moist air rises only after it's been warmed, whereas cold moist air initially descends.
    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

  6. #45
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    Default Re: Upper vs Lower Ventilation (again).

    Roland:
    If warm moist air goes up, and CO2 goes down, and two entrances cause a breeze, I would suggest insulation overhead, dead air under the cluster, and a lower entrance only.
    Regardless of the direction of the moist air, my setup is as you describe: sealed, heavily insulated top - with an infinitely large air space below the cluster, by courtesy of an Open Mesh Floor, left open.

    logicallycompromised:
    Vance G - that is an improvement over "upper ventilation" but will encourage an exchange of warm air at the expense of the bees because the vacuum formed by air entering and exiting the hive body; i.e. venturi is formed.
    No gas-flow restrictions with an Open Mesh Floor.

    Vance G:
    Water vapor also condenses on cold surfaces. If the sides are colder than the top by design, the bulk of the condensation will happen there. The moisture will be out of the way but still available to the bees.
    Indeed - that's an integral part of my system also. From time to time I even see water dripping through the OMF which has condensed on the uninsulated hive walls - but this is only ever a tablespoonful or two. Over the course of a season several gallons of water need to be eliminated from each hive, and yet this water is never observed leaving (except for the odd spoonful) in this liquid form. 'Somehow' it's being eliminated - and very successfully - via the bottom of the hive. In summer, this is easy to explain as the bees can setup their own circulatory system. In winter the mechanism dynamic is far less clear, as the bees tend to be clustered for much of the time.

    BTW - I've always considered CO2 build-up to be pretty-much a non-issue - as bees are able to cope with much higher levels of CO2 than us mammals.
    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

  7. #46
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    Default Re: Upper vs Lower Ventilation (again).

    In post # 29, Little John questioned my usage of the word "You".., Unlike German. English does not not have a plural "You". My "You" meant all of you that had posted previously, a plural "You".
    .
    Vance seems to have the best understanding of the needs of the bees, and the physics needed to satisfy those needs. There is no right/wrong, , but there may be a better/worse. That said, every year is different, so the "Best", may not be the best every year, but the best over many decades.

    Crazy Roland

  8. #47
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    Default Re: Upper vs Lower Ventilation (again).

    Quote Originally Posted by Roland View Post
    In post # 29, Little John questioned my usage of the word "You".., Unlike German. English does not not have a plural "You".
    Crazy Roland
    Sad, but true. It used to, when thee and thou were singular, and ye and your were plural. You could try y'all or youse guys. OT, but it was hard to resist. :-)

  9. #48
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    Default Re: Upper vs Lower Ventilation (again).

    Thanks for that Roland - I wasn't sure which 'individual' you were addressing - it never occurred to me you meant "all you guys".
    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

  10. #49
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    Default Re: Upper vs Lower Ventilation (again).

    Quote Originally Posted by mgolden View Post
    Merry Christmas to everyone.



    ?????????

    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.
    A frosty upper entrance in the middle of a cold snap tells me the colony is alive and I can sleep another night That said, this has been the mildest winter we've experienced since moving to Northern Wisconsin 34 years ago, not much snow either. So far anyway with 4 months of winter to go. I often have to poke a hole through the stuff to allow built up condensation to escape.

    But with temps nearing 40F today, we've got bees flying and pooping all over the snow. Hoo-Ray!

  11. #50
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    Default Re: Upper vs Lower Ventilation (again).

    just thought of another variable which helps explain some peoples experiences...
    if the bees are not impeded, they will cluster directly on the top cover. i noticed this and do not put emergency feed in the middle but on the perimeter of the hive body.
    why does this make a difference?
    i have spoke of this temperature gradient formed around the bees as a bubble which reduces the chances of condensation forming near them. well if the bees are not able to be in the extreme top of the hive because these contraptions people build to feed, than this bubble becomes smaller and condensation will form closer to the bees. as previously stated, the warmer the air the more moisture it can hold. the warmer air will be at the top away from the bees thus increasing the propensity for moisture to fall out of solution closer to the bees.

  12. #51
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    Default Re: Upper vs Lower Ventilation (again).

    >I'm suggesting that moist air rises only after it's been warmed, whereas cold moist air initially descends.

    All the moist air in a bee hive in winter is warm. It comes from 70 F to 93 F bees and is the metobolic output from generating heat.
    Michael Bush bushfarms.com/bees.htm "Everything works if you let it." ThePracticalBeekeeper.com 42y 40h 39yTF

  13. #52
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    Default Re: Upper vs Lower Ventilation (again).

    Quote Originally Posted by Michael Bush View Post
    >I'm suggesting that moist air rises only after it's been warmed, whereas cold moist air initially descends.

    All the moist air in a bee hive in winter is warm. It comes from 70 F to 93 F bees and is the metobolic output from generating heat.
    As usual we get the straight and simple answer from MB. Thanks Man!

  14. #53
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    Default Re: Upper vs Lower Ventilation (again).

    Quote Originally Posted by Michael Bush View Post
    >I'm suggesting that moist air rises only after it's been warmed, whereas cold moist air initially descends.

    All the moist air in a bee hive in winter is warm. It comes from 70 F to 93 F bees and is the metobolic output from generating heat.
    Moist air from catabolism may indeed start off near the centre of the cluster as being warm - but then has to pass through a fairly thick layer of bees which are forming an insulation layer around that cluster. The temperature of the outermost layer of bees will be relatively cold (or else they wouldn't be functioning as an efficient insulator) that is, fairly close to ambient, and so the moist air will eventually leave the cluster at, or close to, that reduced temperature - and NOT at the temperatures seen at the cluster's centre.

    And at times other than winter ? You appear not to believe in the Latent Heat of Vapourisation.
    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

  15. #54
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    Default Re: Upper vs Lower Ventilation (again).

    Quote Originally Posted by little_john View Post
    The temperature of the outermost layer of bees will be relatively cold (or else they wouldn't be functioning as an efficient insulator) that is, fairly close to ambient, and so the moist air will eventually leave the cluster at, or close to, that reduced temperature - and NOT at the temperatures seen at the cluster's centre.
    I wonder if you could elaborate on this, I'm not picking up on your point or perhaps misreading.

    Say the ambient temperature is 20 F. Moist vapor exiting the outer layer of the cluster has to be at least 40 F, otherwise the insulator bees would be paralyzed. Won't this relatively warmer air still rise?
    To everything there is a season....

  16. #55
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    Default Re: Upper vs Lower Ventilation (again).

    The air temperature near the sides and bottom of the cluster will be near the 40 F. figure LJ mentions and is corroborated by instrumental data from wintering hives. The temperature immediately above the cluster will be much higher if the top is well insulated. I dont think it is easy to accurately predict what the air flow pattern will be or how strong it will be. A bubble of lighter air can be quite stationary at the top of a relatively narrow column.

    A couple of points to ponder;

    The weight of a given volume of air will vary, both with its temperature, and its moisture content. Higher moisture content makes air lighter, not denser.

    Moisture as well as oxygen and carbon dioxide can be exchanged by the process of diffusion without the need for actually replacing the air volumes containing them.

    Is it a possibility that there is not the amount of convection currents occurring as is being visualized. Sometimes the visions we construct in our minds can lead us to assumptions that cloud our arguments.
    Frank

  17. #56
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    Default Re: Upper vs Lower Ventilation (again).

    Quote Originally Posted by Mike Gillmore View Post
    I wonder if you could elaborate on this, I'm not picking up on your point or perhaps misreading.

    Say the ambient temperature is 20 F. Moist vapor exiting the outer layer of the cluster has to be at least 40 F, otherwise the insulator bees would be paralyzed. Won't this relatively warmer air still rise?
    You could well be right under such conditions. I was considering the conditions which exist within British hives during our somewhat milder winters - perhaps this is why bottom ventilation/ bottom entrances etc works so well over here, yet is not favoured in areas which experience much colder winters ?
    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

  18. #57
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    Default Re: Upper vs Lower Ventilation (again).

    Deleting my post, probably not add anything or relevant.
    Last edited by bob128; 01-13-2019 at 08:48 AM.

  19. #58
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    Default Re: Upper vs Lower Ventilation (again).

    How about some actual hive measurements ...

    FIGURE 2. – Temperature readings ( F.) and brood and bee location one comb west of center of cluster at outside temperature of 7.

    That graphic is from a USDA study of hive thermology. The [ambient] temperature outside the hive was 7 degrees F.
    The numbers shown in the graphic are air temperature at the various points inside the hive.

    The study is here: https://beesource.com/resources/usda...-bee-colonies/
    Note that there are 2 supporting graphic pages that are outside of that link, Go here for a complete listing / page links:
    https://beesource.com/resources/usda/
    Look for the paper/group called "The Thermology of Wintering Honey Bee Colonies"
    Graham
    USDA Zone 7A Elevation 1400 ft

  20. #59
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    Default Re: Upper vs Lower Ventilation (again).

    rader, thank you for that comprehensive and scientific study!

    after reading it, i will now offer an apology to Vance G for critiquing their wintering method. based on this study, there is a chance the location of their hole may promote more cleanings flights than most. the idea which compliments this temperature gradient bubble i mentioned is that the the lowest temperature within the hive will be near the bottom entrance, we know this. if this temperature does not approach 40f the bees will likely not pass through it for cleansing flights despite the outside temperature being conducive for such behavior. the goal with having a small upper entrance is placing it in a location still below the cluster to preserve the heat but also allow the bees to fly on marginal days. in the experiment rader linked, the hives upper entrance was about 9" from the top. i am critical of the hive body volume within the tests ([3 stack] langstroth square hive - 12 medium frame boxes across ), i wish the density of bees was stressed as i believe most beekeepers have too much hive volume. if we only have 9" of hive body i do not see the benefit in adding a second entrance like this experiment; the upper entrance was ~9" down just like our bottom entrance would be. the experiment did concede the increased thermal demand placed on the bees with upper entrances but concluded the benefits of more cleaning flights outweighed the difference. i believe we can get the best of both worlds by reducing colonies into single deep box and not using the upper entrance. our colonies are less stressed, and more efficient this way.

    this experiment showed me there could be some benefit to a middle entrance if you have excessive hive volume but i believe this can be improved upon by having reduced hive volume and solo bottom entrance which reduces stress on bees while still encouraging additional cleaning flights.

    thank you all for your contributions, even you bob128(i saw pre-edit and needed to inform myself more about your idea before i made a comment). continue to fight the good fight! live long and prosper!

  21. #60
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    Default Re: Upper vs Lower Ventilation (again).

    Hmmm - I think there's been a tad too much focus here solely on the moisture content of the air within a beehive (which is probably my fault) - so maybe it's time for some elementary chemistry ...

    Oxygen has a molecular weight of 32, and Nitrogen 28 - so, discounting all other gases and bearing in mind that Nitrogen is 80% of the whole - let's say the combination of these two major components of the atmosphere results in a molecular weight for 'air' of 29.

    Ok, so as we know only too well, Water has a molecular weight of 18, which is 11 less than that of dry air (or rather the above Oxygen/Nitrogen mix) - so yes, it is indeed lighter than a molecule of dry air.

    On the other hand, Carbon Dioxide has a molecular weight of 44, or 15 more than the above dry air - i.e. it is more heavier than that air, than water is lighter.

    Now - let's examine what happens when a molecule of sugar (using Sucrose as an example) is oxidised during metabolism - the balanced equation being:

    C12H22O11 + 12O2 > 11H20 + 12CO2 (sorry about not being able to show subscripts)

    As you can see, 12 molecules of oxygen are required for the complete catabolism of one molecule of sugar, during which process 11 molecules of water and 12 molecules of Carbon Dioxide will be produced by the bees, whether these are clustered or not. We see one more molecule of the heavier Carbon Dioxide being produced than of the lighter Water molecule. And so - with all other issues being equal (which of course they're not) exhaled air from honeybees will be heavier than dry air, and not lighter, as is so often claimed.

    Now against this, one needs to factor in the effects of temperature, and the fact that this exhaled air is entering an environment which already contains some water (in the form of water vapour) and some level of existing carbon dioxide.

    Hmm - the situation is now getting pretty complicated, and in view of the above I wouldn't now like to predict whether exhaled air either rises OR falls ... but I'm convinced that it's not just a simple case of "moist air rises" as seductive as such a simplistic idea may seem.
    LJ
    Last edited by little_john; 01-13-2019 at 12:04 PM.
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

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