hive ventilation - sauna or chimney?

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admanga

New Bee
Joined
May 20, 2024
Messages
17
Reaction score
10
Location
Grenoble
Hive Type
warre
Number of Hives
1
[Warre discussion alert - for those that are allergic - please leave now]

1. Ventilation

There seems to be strongly conflicting views on ventilation. Do the bees need a hive with sauna-like conditions or chimney-like conditions?

On helping me to set up a hive for new bees, a longtime Dadant user advised “cover the ventilation hole/porter bee escape in the crown board with a square of card” and “don’t remove the plank below the varroa board until temperatures reach 30 degC”. He and other users therefore are aiming for sauna conditions for the bees.

Next, I’ll turn the rest of this discussion towards the Warre hive, as I’ve started studying that design, and thanks to David Heaf, there is a good collection of links to books and articles about it (https://warre.biobees.com/index.html). I’ve studied that site and I’ve read some of the original texts in French by developers of various more recent versions of that hive.

Strict Warre hives use a cloth topbar cover and a “cushion” which is typically a box of wood shavings as insulation. In theory, this setup works as a chimney that the bees regulate by propolising the topbar cover cloth.

Delon and others say that it is beneficial for the bees if the top of the brood chamber is closed to retain heat (except for winter when some airflow is needed to prevent mold). This could be likened to a nest in a tree, which would typically be closed at the top and open below. Delon recommended a well-insulated crown board (30 mm of wood-fibre insulation) so that humid air descends and condenses down below by the entrance. Delon criticises crown boards with a hole in them. If a crown board contains a bee escape then the bees seal it up indicating that their priority is to retain heat. Concerning varroa, apparently they do not thrive so well in hot and humid conditions. So Delon was in favour of sauna-like conditions.

Guillaume and Freres on the other hand preferred a ventilated roof but criticised the original Warre design for its sealed by propolis top cloth and lack of airflow above the cushion. G&F used a mosquito net over the top bars and a ventilated roof volume above the cushion. (They recommend that this could be retrofitted to Dadant type hives for improvement of their ventilation). The bees fill the mosquito net with propolis and can adjust hive airflow themselves by adding or removing propolis. Above the ventilated part, they also used a thick layer of proper insulation like Delon. G&F also recommended a solid wooden floor, only replacing it with a screen to check varroa in spring for a few days. They are strongly critical of ventilated floors because the bees have no control over airflow and have to use more energy to keep warm.

2. Whole hive insulation
Warre wrote that external insulation was not needed for his hive and was even detrimental to the chances of the bees surviving winter. His logic was that bees in a lightly insulated hive enter their “hibernating” state, while those in well-insulated hive continue to work and use up honey stores unnecessarily.

Delon liked to add external insulation for winter and also his hives were built of 30 mm thick wood instead of 24 mm as per Warre. He criticised Warre by noting that cushion insulation which absorbs moisture is not insulating. I get his point. He also waxed the inside of hives to prevent the walls absorbing moisture. Again, this seems logical if there is a means to evacuate condensed water. I do imagine that his hives stood in a puddle of condensation, while Warre’s probably got rid of some moisture as water vapour.

By the way, Delon’s 45 degree sloping entrance that is minutely adjustable by moving the brood box backwards/forwards seemed like a good idea that went nowhere.

I’m still none the wiser because of these experts' conflicting views. Warre is credible, he spent his whole life studying bees (read his book before writing him off as a mad monk). Delon is credible, having managed hundreds of commercial hives, while Guillaume and Freres are much more recent and write in a highly-opinionated style but without data to back up anything they say (in all I’ve read so far). But possibly because G was the scribe while F was the beek.

The purpose of the “cushion” with moisture absorbing wood shavings would appear to be to wick away moisture. I agree with Delon that if it becomes damp, then its not going to be much of an insulator. I'm not using the cushion for now.

I have put a layer of insulation between the crown boards and flat galvanised roofs to protect the hives from excess summer heat. And I've left the crown board bee escape partially unblocked, so there is a slight chimney effect. But the bees have definitely slowed down this month in their building.

And I’m a bit dismayed that Guillaume and Freres reject the ventilated floor for Varroa management, as my hive purchases were motivated by that feature rather than any other for both Dadant and Warre. For now, the removable ventilation board is left in place. Guillaume and Freres were of the opinion that bees in a Warre are so healthy that they did not need the anti-varroa floor (or any chemical treatment). But no numbers for colony survival were given - impossible to judge their credibility.
 
[Warre discussion alert - for those that are allergic - please leave now]

1. Ventilation

There seems to be strongly conflicting views on ventilation. Do the bees need a hive with sauna-like conditions or chimney-like conditions?

On helping me to set up a hive for new bees, a longtime Dadant user advised “cover the ventilation hole/porter bee escape in the crown board with a square of card” and “don’t remove the plank below the varroa board until temperatures reach 30 degC”. He and other users therefore are aiming for sauna conditions for the bees.

Next, I’ll turn the rest of this discussion towards the Warre hive, as I’ve started studying that design, and thanks to David Heaf, there is a good collection of links to books and articles about it (https://warre.biobees.com/index.html). I’ve studied that site and I’ve read some of the original texts in French by developers of various more recent versions of that hive.

Strict Warre hives use a cloth topbar cover and a “cushion” which is typically a box of wood shavings as insulation. In theory, this setup works as a chimney that the bees regulate by propolising the topbar cover cloth.

Delon and others say that it is beneficial for the bees if the top of the brood chamber is closed to retain heat (except for winter when some airflow is needed to prevent mold). This could be likened to a nest in a tree, which would typically be closed at the top and open below. Delon recommended a well-insulated crown board (30 mm of wood-fibre insulation) so that humid air descends and condenses down below by the entrance. Delon criticises crown boards with a hole in them. If a crown board contains a bee escape then the bees seal it up indicating that their priority is to retain heat. Concerning varroa, apparently they do not thrive so well in hot and humid conditions. So Delon was in favour of sauna-like conditions.

Guillaume and Freres on the other hand preferred a ventilated roof but criticised the original Warre design for its sealed by propolis top cloth and lack of airflow above the cushion. G&F used a mosquito net over the top bars and a ventilated roof volume above the cushion. (They recommend that this could be retrofitted to Dadant type hives for improvement of their ventilation). The bees fill the mosquito net with propolis and can adjust hive airflow themselves by adding or removing propolis. Above the ventilated part, they also used a thick layer of proper insulation like Delon. G&F also recommended a solid wooden floor, only replacing it with a screen to check varroa in spring for a few days. They are strongly critical of ventilated floors because the bees have no control over airflow and have to use more energy to keep warm.

2. Whole hive insulation
Warre wrote that external insulation was not needed for his hive and was even detrimental to the chances of the bees surviving winter. His logic was that bees in a lightly insulated hive enter their “hibernating” state, while those in well-insulated hive continue to work and use up honey stores unnecessarily.

Delon liked to add external insulation for winter and also his hives were built of 30 mm thick wood instead of 24 mm as per Warre. He criticised Warre by noting that cushion insulation which absorbs moisture is not insulating. I get his point. He also waxed the inside of hives to prevent the walls absorbing moisture. Again, this seems logical if there is a means to evacuate condensed water. I do imagine that his hives stood in a puddle of condensation, while Warre’s probably got rid of some moisture as water vapour.

By the way, Delon’s 45 degree sloping entrance that is minutely adjustable by moving the brood box backwards/forwards seemed like a good idea that went nowhere.

I’m still none the wiser because of these experts' conflicting views. Warre is credible, he spent his whole life studying bees (read his book before writing him off as a mad monk). Delon is credible, having managed hundreds of commercial hives, while Guillaume and Freres are much more recent and write in a highly-opinionated style but without data to back up anything they say (in all I’ve read so far). But possibly because G was the scribe while F was the beek.

The purpose of the “cushion” with moisture absorbing wood shavings would appear to be to wick away moisture. I agree with Delon that if it becomes damp, then its not going to be much of an insulator. I'm not using the cushion for now.

I have put a layer of insulation between the crown boards and flat galvanised roofs to protect the hives from excess summer heat. And I've left the crown board bee escape partially unblocked, so there is a slight chimney effect. But the bees have definitely slowed down this month in their building.

And I’m a bit dismayed that Guillaume and Freres reject the ventilated floor for Varroa management, as my hive purchases were motivated by that feature rather than any other for both Dadant and Warre. For now, the removable ventilation board is left in place. Guillaume and Freres were of the opinion that bees in a Warre are so healthy that they did not need the anti-varroa floor (or any chemical treatment). But no numbers for colony survival were given - impossible to judge their credibility.
Great post Admanga. Ventilation has been argued about by beekeepers for a very, very long time. I was looking in an old American Beekeeping Journal a few years ago (perhaps from the 1870's) and there was a report there where the matter had been discussed at a meeting of some sort and the vote was split about half way, for and against. Presumably that wasn't when the difference of opinion first emerged.
Research has been done down here to indicate that the decision to ventilate should be based primarily on external humidity.
 
On helping me to set up a hive for new bees, a longtime Dadant user advised “cover the ventilation hole/porter bee escape in the crown board with a square of card”
It seems like you encountered a pretty wise beekeeper. Forget this rubbish about 'sauna conditions' the bees will sort out ventilation/air circulation and humidity themselves without us unnecessarily interfering
His logic was that bees in a lightly insulated hive enter their “hibernating” state, while those in well-insulated hive continue to work and use up honey stores unnecessarily.
a theory which has now been proven to be absolute rubbish
 
Wow, not sure where to start with this. Most, if not all, of your discussion points are not exclusive to Warre hives. If you want to expand to review experience with other hive types, search the forum for some very inciteful discussions on others experiences of how to work with the bees rather than against them.
 
I overwinter hives in insulated boxes with minimal ventilation. (Slowly discarding OMF floors).
Poly nucs? I use as supplied.
Last Winter losses in a cold windy and damp place were MUCH lower than my beekeeping colleagues on OMFs. - (150- 250meters above sea level, edge of Staffordshire Moorlands)
 
@jenkinsbrynmair absolutely not forgetting the sauna aspect. Guillaume and Freres even though that an antiseptic shower is created with a heavily propolised mosquito net above the top bars or frames and condensation containing propolis raining down on the bees.

@madasafish, Since writing the post, I've read earlier discussions here about OMF floors and insulation. Very good comments, and I will look to insulating below the mesh in time for winter. Already at the hive top, I put 40 mm of cork under the galvanised roof and the hive gets partial shade mid afternoon. I have to to plan for -12 to +40 degC. Humidity is unlikely to be a problem, though months of drought can happen.
 
@jenkinsbrynmair absolutely not forgetting the sauna aspect. Guillaume and Freres even though that an antiseptic shower is created with a heavily propolised mosquito net above the top bars or frames and condensation containing propolis raining down on the bees.

@madasafish, Since writing the post, I've read earlier discussions here about OMF floors and insulation. Very good comments, and I will look to insulating below the mesh in time for winter. Already at the hive top, I put 40 mm of cork under the galvanised roof and the hive gets partial shade mid afternoon. I have to to plan for -12 to +40 degC. Humidity is unlikely to be a problem, though months of drought can happen.
PM me if you like.
There are a few unscientific myths bandied about.
 

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