Do you ventilate through the bottom?

[eltalia]

Do lets' s open that old hoary soapbox of ventilated bottomboards(VBB)..?...or SSB
as modern b'keeps know them.
Posting into this Aussie themed forum as much of the argument for using such a
device comes from Northern Hemisphere b'keeps - and whilst I have reservations
around the management of SSB in those climes I do accept some b'keeps in some
microclimates may have good reason to use them.

Essentialy VBB originated out of the original adaptation of Langstroths principles
of ventilation and included ventilated lids... in Europe.
Transferring those designs to Aussie climates saw mixed results yet the overiding
occurance of pest intrusion - particularly wax moth - demanded change.
Bees will always go after foreigners with great gusto to either kill and remove or
glue them down insitu.
--but only if they can get to the body --
There are a thousand stories of pests surviving in VBBs, some results passive
others reeking havoc. Attached is a recent example of an old pet hate of mine, this
one in a modern SSB but equally prevailing in the now ancient and out of service VBB.
These guys are deadly, have no misconception of that, and hide exactly where the
unknowing willingly put their hand, either in the hivebody or stored in the shed.

Today we have SHB (small hive beetle), a critter that will use the smallest of crevices
to hide in, unreachable by the EHB. To combat the SHB in assisting the EHB SSB must
be removed AND any joints in hivebody woodwork sealed.
When EHBs can get at SHBs they will control them where the colony is at CM (critical mass)
or slightly less. Anything else the b'keep has to be in there regularly to kill the beetles.

Bill

[Acebird]

Bill the SBB was invented to manage varroa not for ventilation.  The system should have the ability to prevent any ventilation to the hive through the screen.  It can be a plus for beetles or a minus depending on how it is used.

[little john]

Bill the SBB was invented to manage varroa not for ventilation.  The system should have the ability to prevent any ventilation to the hive through the screen. It can be a plus for beetles or a minus depending on how it is used.

Have just GOT to take issue with that POV ...

It may well be true that OMFs (Open Mesh Floors) were originally intended for varroa mites to fall through - just as Viagra was originally intended to treat heart conditions - but it was then discovered (in both of these cases) that they were far more useful for alternative purposes.

Open Mesh Floors can be used to provide ventilation all year round.  I leave my OMFs open for exactly this purpose, and only close those on hives which are unprotected from gale force winds, such as is happening today as I write this.  BTW - I have one colony on 'life support' right now, and closed it's OMF at midday yesterday.  The temperature in the hive has risen by less than 1 deg C following this action - thus (on the strength of one example) dispelling the myth that OMFs cause excessive cooling from high winds during winter.

With ventilation being thus provided at the base of the box, the top can then be fully sealed - which is something that the bees constantly aim to achieve themselves by their use of propolis within that area.  But - some people are wedded to other ideas, and nothing I can ever say will change that.

Re: SHB - that's an issue I know virtually nothing about, but I understand that they fly through hive entrances with impunity anyway, so any hive opening will therefore allow their entry.
LJ

[eltalia]

Bill the SBB was invented to manage varroa not for ventilation.

Sure...buuut have you any idea of numbers of beeHavers who swear
by using them for ventilation? Clue..?.. it's thousands, mostly those
who were sold them as flatpacked whole kit. Can you say "FlowHive"?

As that pix shows they do become havens for pests as bees cannot
get at the animal, or if they can there is nothing tangible to stick larger
critters to.
As I acknowledged, there do exist microclimates where they have a
use, albeit under astute management as LJ has illustrated, that use
not entirely understood just as many do not 'get' how to use queen
excluders.

Bill

[Acebird]

Bill I don't know what your beef is with the Flow Hive other than it is common with commercial operators to bash the success.  You are the first that made any connection with it and ventilation that I know of.  I don't believe there are any claims in their patent declarations on ventilation.
We in the north ventilate our hives because clusters have been known to drown due to moisture freezing on the lid and then melting all at once.  The bees have no defense against this phenomena.  It is a responsibility of the beekeeper to prevent it from happening.  I will say this until I am blue in the face that the amount of ventilation that you get is dependent on the smallest hole in the hive be it the top or the bottom.  Fourteen molecules of air does not enter a closed box unless 14 molecules of air exits the box.  I have run wide open mesh bottoms in the dead of winter (-20F) and the hives survived.  That is with an open top vent.  The top vent increases ventilation greatly and it is excessive if you have a screen bottom board fully open.  The problem being is you cannot control where the air comes into the hive if the floor is fully open.  The air can pass over developing brood and chill them.  I found that the bees actually closed off the bottom of my frames to prevent this from happening.  Oddly enough they did not close off the screen which would have taken less propolise.  In my beginning years I had a hole in each box and that is excessive.  I don't do that anymore.
Now my lower entrances are only restricted by my mouse guards.  So there is more of an opening at the bottom entrance then there is in the top vent.  I do not use my screen bottom board for ventilation.  It is closed off by a board in the back of the hive that I can easily move to access the plastic tray.  IMO a screen bottom board is not a good device for controlling ventilation of the hive.
I don not like quilt boxes for the same reason.  You cannot control the flow of air passing through the hive without installing a baffle under the quilt box.
The reality is you have to have an entrance to a hive whether it is upper or lower.  If your hive needs ventilation (the problem is local conditions) then the vent should be aligned with the entrance so air passes up the wall and not through the brood chamber.
I know many people in warmer climates do not vent their hives they rely solely on the entrance for air changes.
Flow hive or no flow hive, venting is a requirement for local conditions.

[Acebird]

Open Mesh Floors can be used to provide ventilation all year round.

In my view this is a mistake.  An open mess floor will affect the efficiency of bees fanning the entrance when it is too hot.  This is something the bees are very capable of doing and causes less stress then having the floor open.  The air that the bees try to push into the hive by fanning will just flow out the bottom taking the path of least resistance.

[eltalia]

Bill I don't know what your beef is with the Flow Hive other than it is common with
 commercial operators to bash the success.
(edit)

[cough]
errrrr.. I have no "beef" with FlowHive[tm] Brian, quite the contrary.
I am actually a customer, a "happy camper" for now - whilst testing
stuph.
Come back in two years time to see if that has changed?
As for your ventilation (pun) ...?...I am addressing all such things
in a submission to that "cold weather beekeeping" thread when
I have that work done - placed on hold whilst we locally had our
own tribulations, and more yet to come, by forecast.
Stay tooned :)

psssst... I am no longer "commercial", retired gentry now...just like
most members here. So please resist colouring my comments from
a bias which is not at all present. I was an Apiarist loooong before
a businessman :)

Bill

[Acebird]

Sure...buuut have you any idea of numbers of beeHavers who swear
by using them for ventilation? Clue..?.. it's thousands, mostly those
who were sold them as flatpacked whole kit. Can you say "FlowHive"?

Bill, this is a bias.  Not something I would expect a happy camper to say on a public forum.

[eltalia]

Sure...buuut have you any idea of numbers of beeHavers who swear
by using them for ventilation? Clue..?.. it's thousands, mostly those
who were sold them as flatpacked whole kit. Can you say "FlowHive"?

Bill, this is a bias.  Not something I would expect a happy camper to say on a public forum.

I disagree, strongly. An example is given, nought else.
Brian.
What you expect from a public forum nobody can
accomodate, as much of your comments added to many
a topic well illustrate.

Bill

[little john]

Seems like you guys need some evidence ...

Moist air is lighter than dry air - every pilot knows that, and that's why we have clouds up there in the sky.

BUT ... (isn't there always a 'but' ?) - the missing piece of the jigsaw which is so often overlooked is that of the evaporative cooling which occurs as moist air is formed.  This cooling makes the molecules of water vapour denser, and thus heavier than air.  Such air will then fall to the ground, or to the bottom of a box.

Here's an example where you can see such water vapour hugging the ground:



It will stay like that until 'the sun burns it off' - that is, until solar radiation reverses the heat loss, thus making that suspended moisture lighter than air again (and invisible), so that it rises high into the sky, where it cools at altitude and once again becomes visible as a cloud formation.

But in a box, there is no solar radiation, and so unless heat from the colony is sufficient to offset that cooling from evaporation (somewhat unlikely in winter), the moist air will remain at the bottom of the box - that is, unless some provision has been made for it to escape, of course.

Such cold moist air in winter causes black mould to form - always at the bottom of those boxes with solid floors:





And - if you want even more evidence of this phenomenon - check out the multi-billion dollar timber (lumber) seasoning industry which has it's origins in Oregon - where timber is treated with steam inside huge insulated sheds - with the excess moisture being drained-off ... again, always from the bottom.

Yes - you can allow moisture to escape from holes in the top of the hive, but this will be done at the expense of loss of heat.  Which is an excellent idea during a summer in the tropics, but not so clever in more temperate regions.  There are sound reasons why bees try their hardest to seal-up the tops of their hives with propolis.  You can work with the bees, or against them - it's your choice, always.
LJ

[eltalia]

Seems like you guys need some evidence ...

... not this black duck, LJ :-)

I have seen first-hand hundreds of thousands of dollars in
retail stock written off (damaged) by the very same
phenononmen (sp?) seen on a smaller scale within hive
structure.
I'd shy away from this 'debate' normally, as it is pointless
to attempt to interpret the science for b'keeps in a format
which would suddenly change what many take as
"written in stone". Even introductory principles extract "hey,
kanga rider, what would you know about cold weather".
Fact is, I do... (design and fix) such 'things' is my actual
core expertise - read  "profession".
What I have elected to do is construct a model and present
that in the Cold Weather thread, for review and consumption,
the masticating kind, not the illness type consumption :-))

There are sound reasons why bees try their hardest to seal-up the tops of their hives with
 propolis.  You can work with the bees, or against them - it's your choice, always.
LJ

Exzackery.
Nice panaramas LJ...reminds me of frosty mornings in
Gippsland and other like environs here.

Bill

[Bamboo]

Seems like you guys need some evidence ...

Moist air is lighter than dry air - every pilot knows that, and that's why we have clouds up there in the sky.

LJ

Mate you obviously have no idea about "moist air" as you put it and probably should have spoken to a pilot. I used to have my pilots licence. I could give you a whole lesson on clouds, density, and why pilots avoid them but I suggest you go and learn a little about meteorology.

[little john]

Yet another unnecessarily personal and abrasive post from Bamboo who appears intent on starting a fight. 

At no point did I mention 'avoiding clouds', from which I assume you are referring to the up-draughts within cumulonimbus.  The mechanism for clouds appearing in the sky applies equally to fair-weather cumulus, cirrus, and all the rest ...

Molecular weight of oxygen = 32
Molecular weight of nitrogen = 28

Molecular weight of Water = 18

Therefore moist air (air containing moisture) warmed sufficiently to compensate for evaporative cooling will always be lighter than dry air.

Little John (not my real name, surprisingly),
formerly of 12 Sqn RAF (Buccaneers)

[Bamboo]

LJ I am not picking a fight. I was merely saying that you were incorrect regarding moist air being light.
Not sure where you got your figures from but your molecular weights are incorrect.
Oxygen is 15.999
Nitrogen is 14.006
You are correct with water at 18

Which means my friend water is always heavier. Your picture illustrates the point perfectly and why it rains. If water was lighter than air it would never rain.

[little john]

LJ I am not picking a fight. I was merely saying that you were incorrect regarding moist air being light.
Not sure where you got your figures from but your molecular weights are incorrect.
Oxygen is 15.999
Nitrogen is 14.006
You are correct with water at 18

I got my figures from memory, as one of my degrees is in Organic Chemistry.

The figures you have quoted for Oxygen and Nitrogen are their atomic weights - but in the gaseous form they exist as diatomic molecules: O2 and N2 (sorry, I can't quickly figure out how to show subscripts in .html), hence their molecular weights are twice their atomic weights.
LJ

[eltalia]

Nahhh LJ, I can 'hear' Paul talkin' like 'n that.
His post merely lacks filtering for this "international"
 audience, like :-)

But both exchanges exhibit plainly why it is I avoid such
let's say, "technicalities at conference level", no audience
participation, and the only winner is g00gle.com.

Fact is condensation within a hive body (structure) is neither
Met. nor a controlled barometric event as each of you rely on.
It is simply a matter of heat exchange - or for many suffering
mould, the lack of.

As for the wings (member waaaving)?
I know boats... I flew in Papua and so know full well to avoid
Cloud, buggers got rocks an' trees in 'em @10, 000 feet!
FUN times :-)))

Bill