Do you cover or leave open your crown board holes

[Chris Luck]

AFAIK bees put a thin film of propolis over all of the interior surfaces of their hive or cavity and I thought it was an anti septic barrier amongst other things.

Chris

 

[MandF]

That sounds logical, and would explain why they propolise the underside joins of the CBs.

 

[Shabro]

Surely by leaving the feeder holes open you are in effect creating a chimney effect where all the heat will be lost as draws in air from underneath? This cant be good for the bees surely?
I put mesh over initially , and it was all propolised over, who am I to argue?

 

[MandF]

How are you creating a chimney effect? Where is the heat escaping, and to what degree? I buy the extra space that will effectively be heated, but not the chimney effect - my boxes have small gaps in them, as much heat escapes through those than through the vents in the roof if/when a feed hole is left open to allow bees to clean up comb.

Also, who are you arguing with re: propolis? Do you remove brace comb routinely? or propolis on frame lugs? Or let your bees swarm? Or remain queenless in a laying worker hive? This is exactly what we are discussing in my 'bee thinking' thread

 

[MandF]

Also, I just popped down to look at my hives, 2 of them are busily fanning away at the entrance to get the air circulating - would it help if I uncovered the feed holes now?

 

[victor meldrew]

Have another look, you may find that they are fanning in two directions to maximise the area ventilated; whereas with holes uncovered the air would likely short circuit ( take the easy route .)
I spent some time working in the coal mining industry as a boy , the ventilation of coal faces, side roads etc. needed constant attention ! Having a down cast shaft for air ingress and an up cast shaft for air egress, without complex internal regulation would have resulted in large areas of any mine being improperly ventilated ,allowing pockets of the various gasses associated with coal mining to accumulate !
VM

 

[MandF]

As it happens one of the hives has 2 entrances, or rather a block in the middle of the usual entrance, I did this when trying to drift bees into it.

Anyhow, there are bees on both sides fanning the air out.

If you have an OMF would it make much difference if you had a feed hole open? How much air will be drawn down from the roof space vs air drawn up and around through the OMF?

 

[victor meldrew]

If you have an OMF would it make much difference if you had a feed hole open? How much air will be drawn down from the roof space vs air drawn up and around through the OMF?

I personally think so My reasoning being, the omf allows a large volume of low pressure air to enter hive , if open feed hole is open, the hot air will escape creating a venturi effect ( the escaping air will have to increase in speed thus generating the chimney effect )A rising tapering column of air will be self sustaining and leave the upper and outer recesses largely unventilated , save foe maybe a little eddying ?
VM

 

[MandF]

I wonder if anyone has made any infrared heat films of heat movement in hives?

Re venturi idea, wouldnt this be the case if the hot air had a way to escape out into the atmosphere? If it doesnt (or has v. little) then the temp in the roofspace would stabilise and you'd end up with a temperature inversion?

Being a private pilot I have a slightly different take on convection/advection currents etc, so thats what I see happening with an open feed hole?

 

[Walrus]

Surely, if one is as fascinated in this subject as some appear to be, the answer is to conduct an experiment. Given that to be statistically significant you'd need a lot of hives (maybe 50 with open holes and 50 with closed?) I can't do that. So I chose to listen to the beekepers who have lots of hives and/or make their living from it, because that is the next best thing to proving something for myself - in fact its better 'cos they did all the work

I have changed over to insulated/no hole crown boards because I was convinced by certain members posts, plus additional reading, that this is likely to be beneficial (I have OMFs & cedar hives). It may make no difference; it may be much better or like MandF they may die - it doesn't prove anything 'cos I only have 3 hives. I'm happy with my decision and am happy to benefit from the experience of those who have kept far more bees for far longer than I have.

Someone else, reading what I have read, may conclude diffently to what I did, and that's fine. I am happy with my decision and grateful for this forum sparking off my research elsewhere.

 

[victor meldrew]

I wonder if anyone has made any infrared heat films of heat movement in hives?

Re venturi idea, wouldnt this be the case if the hot air had a way to escape out into the atmosphere? If it doesnt (or has v. little) then the temp in the roofspace would stabilise and you'd end up with a temperature inversion?

Being a private pilot I have a slightly different take on convection/advection currents etc, so thats what I see happening with an open feed hole?

I see where you are coming from but think my analogy of the coal mine ,being an enclosed space , more like a bee hive than the vagaries presented by the open atmosphere ?
I have a little interest in temperature inversion , being a radio ham ,I know that the junction of cold air trapped under warm air during temperature inversions ,acts as a mirror to VHF/UHF radio waves and so increases the distance radio signals travel Sorry it also interrupts TV signals
VM

 

[MandF]

I sort of get the coal mine analogy, except I do think in a hive there is not enough venting to the outside atmosphere via the 2 meshed inserts in the roof, esp if the temp in the roof gets to be a higher temp than the more circulating air below a feed hole, to create the chimney/venturi effect you mention?

For a pilot, a temp inversion often means a mucky layer of haze, but it is beautifully smooth to fly in

 

[REDWOOD]

I wonder if anyone has made any infrared heat films of heat movement in hives?

Re venturi idea, wouldnt this be the case if the hot air had a way to escape out into the atmosphere? If it doesnt (or has v. little) then the temp in the roofspace would stabilise and you'd end up with a temperature inversion?

Being a private pilot I have a slightly different take on convection/advection currents etc, so thats what I see happening with an open feed hole?

I watched a beekeeper light a match and held it one side of the entrance and the flame was being sucked in and then did the same the other side and watched the flame being blown out, to me this indicated that bees circulate the air from one end to the other, probably bees fanning are ripening honey removing moister

 

[Walrus]

I found this very interesting:
http://www.uoguelph.ca/canpolin/Publications/JTB-PAPER-Sudarsanetal-2011.pdf

It looks at simulations of air flows in a solid floor hive with one entrance/exit only. I have the supplementary bits & bobs including videos of air flows in the hive.

The main point is that in ambient temperatures common in the UK (less that 30 degress celsius) there is very good airflow in the hive and air is heated before it enters the brood area. Most air bypasses the brood area. Bees regulate the brood temp in various ways as described in the paper (heat & mass exchange).

It would appear that at higher ambient air temperatures, using the model in the research, the air flow is much less and there can be a higher build up of carbon dioxide, but the researchers concede that more work needs to be done on this because the bees can change this by rearranging their position on the comb.

My overall take on it was that for UK temperatures, a hive with a solid floor and only one hole is very capable of effective thermoregulation and elimination of CO2. The addition of an OMF is likely to increase air flow around the edges of the hive IMO.

I also appreciated what Dave Cushman, who was rarely wrong with respect to beekeeping in the UK, had to say on ventilation:
http://www.dave-cushman.net/bee/ventilation.html

 

[Dusty Rhodes]

I found this very interesting:
http://www.uoguelph.ca/canpolin/Publications/JTB-PAPER-Sudarsanetal-2011.pdf



I also appreciated what Dave Cushman, who was rarely wrong with respect to beekeeping in the UK, had to say on ventilation:
http://www.dave-cushman.net/bee/ventilation.html

It's certainly well argued. But he misses out, amongst other things, consideration as to whether insulation is required/problematic during summer.

Dusty

 

[Skyhook]

Also, I just popped down to look at my hives, 2 of them are busily fanning away at the entrance to get the air circulating - would it help if I uncovered the feed holes now?

Leave the poor things alone, theyre doing fine without you disrupting the airflow they're creating.

 

[MandF]

Leave the poor things alone, theyre doing fine without you disrupting the airflow they're creating.

It was a rhetorical question - based on the idea that an open feed hole creates a lot of extra ventilation.

I agree with you - leave them alone, they are able to cope however we configure our hives.

 

[user 6228]

It's certainly well argued. But he misses out, amongst other things, consideration as to whether insulation is required/problematic during summer.

Dusty

4 hives all insulated all with bottom entrances no top vent.
3 hives have solid, highly insulated floors(25 ~ 50mm kingspan) floors, and highly insulted roof and sides(50mm) with entrances 75mm or more or below the floor level. in full sunshine
The colonies are not crowded in that they still have space to expand
No bearding observed. Fanning heard in evening.

 

[Polyanwood]

Where is Pamber Heath? Just wondered as you have got serious insulation, which may do some good, but I wondered what prompted you - do you have extreme weather?

 

[oliver90owner]

do you have extreme weather?

Extreme weather is neither here nor there.

Think early polyhives with no OMF - bees were apparently all right in those - or deep inside a tree (although there might be some cooling water passing nearby, on the way from the roots to the leaves).