Poly Nucs and Hives

[user 6228]

continuing for for a thermal conductance of 0.4w/c/m2.
with expanded foams with conductivity of about 0.03w/c/m2 we therefore need walls 75mm thick, to get the bees to be able to warm up the whole hive at -10C . Thinner walls might still allow the bees to heat up the top half. And internal silvering of the hive will also help. But as regards your orignal question, its liitle difficult without wattage and conductance per bee. As regards heating the honey, that depends on the heat losses from your hypothetical tank

note poyurethane foams are better than polystryene 0.021 has been cited for urethane. wood comes in at 0.12~0.14

 

[Poly Hive]

Bees summer cooler in hot weather in poly. Winter warmer in winter oddly.

They need to cluster far less tightly in winter so isolation starvation is not nearly so common.

As noted brooding in summer is wall to wall.

Propolis concerns. Well it gave me a laugh if nothing else. Never had poly break due to propolis. Never had poly break actually apart from one empty brood body which accidentally got run over by a tractor. I very much doubt if 2" thick cedar would have survived either.

Blow torching is not required. Actually it's not required either for timber now if you think about it. But then it's really about the danger, the noise and the fun ain't it? Be honest with yourself here.

Any other seriously practical reasons for not giving bees better accommodation awaited with interest.

PH

 

[EdNewman]

I know it has been posted here many times, but a search brings back too many posts to trawl through.

I'm going to buy a 14x12 poly nuc to test alongside a wooden version next year. What is the minimum density poly I should be looking for?

Ed.

 

[user 6228]

the higher performance of urethane foams means you can get the ideal conductance with only 50mm. If you are getting a foam hive for its thermal properties, thickness of foam is key especially the roof.
If you cant reach close to the magic conductance number the bees are not able to heat all the hive, hence why they cluster. Now one should consider all the other issues that will drain the cluster heat.
1) condensation - water vapour collecting and falling as cold rain on the bees, the condensation forms a thermal short circuit from the roof to the cluster.
2) radiation loss, the blackened walls of some hives will absorb the radiated heat rather than reflect it back. Yes, using a blowtorch makes your bees cold.
3) metal floors. The metal floor conducts heat from the centre of the hive to the outside walls.
4) floor not protected from cold outside air blowing directly on the floor will make this conduction worse. Having baffles below the floor that prevent cold air movement on to floor will help. having an insulating floor material even better. Putting a super under the floor and one under the brood box will take the cluster further from the cold floor, I dont what the bee will make of it but the thermodynamics say it should work.

 

[Poly Hive]

Never heard of a metal floor.

100gms/litre is the magic number.

PH

 

[user 6228]

Never heard of a metal floor.

100gms/litre is the magic number.

PH

the metal mesh flooring?

 

[sugarbush]

Speaking for all of the US; We generally dislike them. The one pictured in my avitar is the only one I have and I bought it only because my local bee supply is out of all woodenware for the season. I also thought that before I condemned them I should actually use one.

When a bear smashes a wood box it can be glued back together, when it smashes a foam box it can be thrown in the trash.

 

[oliver90owner]

The bees need to maintain an average temperature in the cluster, which if IRRC is about 38C.

Unfortunately not true or even close. Less than 20C, possibly at the core, so that will put a lot of calculations out of the window as the delta T has reduced by about 30%. Secondly it is only the very core of the cluster which needs around 35C, IIRC, (for the minimal brooding which would be taking place) so the average temperature across the cluster would be far less. The temperature at the outside of the cluster will be just a little over 8C as a mlinimum (or bees will fall off and die) so the actual delta T from cluster to outside tempertures is now even more reduced.

Those that accurately monitor hive mass through the winter would be able to plot the stores used and so approximate thermal heat produced. Not a simple relationship as soon as brooding starts and certainly not if the hive retains moisture and gets damp.

I personally doubt that 12 kg of fondant is normally used for conversion to thermal energy in a typical English winter, but hey ho, there will still be a saving if the U value of the hive materials is superior - and as PH says the cluster will not need to be so close to the maximum density in poly than it is in wood, which may reduce the anticipasted savings while at the same time reducing the risk of colony failure due to isolation starvation. All 'trade offs'.IIRC the latent heat of vapourisation of liquid water is 530 time the specific heat of liquid water and there is a fair amount of energy required to convert 11kg of sucrose and ~1kg of water to the gaseous (well vapour) state with no apparent temperature rise.

So to actually model the process is not quite as simple as comparing it to a 20W power source.

RAB

 

[user 6228]

The bees need to maintain an average temperature in the cluster, which if IRRC is about 38C.

IIRC the latent heat of vapourisation of liquid water is 530 time the specific heat of liquid water and there is a fair amount of energy required to convert 11kg of sucrose and ~1kg of water to the gaseous (well vapour) state with no apparent temperature rise.

So to actually model the process is not quite as simple as comparing it to a 20W power source.

RAB

you can get the amount of heat you can extract from burning sugar to carbon dioxide and water from any diet book. Though watch out they are kilocalories even though they call them calories. the info I found says
"The bees at the core of the cluster maintain a temperature of 64-90°, while the outer mantel layer of bees maintain a temperature from 48-57°." these temps are in fahrenhiet. if we are going for nice warm bees lets go for 90f thats 32c . so for -10 thats 40c difference.

 

[Poly Hive]

This is getting silly.

A bear smashes a timber Langstroth and it can be glued together? I doubt it.

If a tractor as mentioned kills a poly it would do the same to a Lang.

If the above happens I can buy three polys for a timber unit.

Metal mesh, never think of that as a metal floor to be honest and if heat is being conducted via the mesh it will flow better to timber, cold than it will to poly warm.

Lovely to see the prejudices being aired. LOL

PH

 

[Norton]

I tested my first Swienty poly-hives this year in Cyprus. I can say from casual observations that the bees do seem be more comfortable in them. Spring build-up was slightly better in the poly-hives, honey production also seems higher, but most importantly they are a lot better in helping the bees cope with the summer heat in Cyprus. We have had temperatures in the high 30's to low 40's - I want to see what happens when we get really high temperatures like last year when we had 46C.
All our mating nucs, 560 of them, in Crete are poly.
Best regards
Norton

 

[sugarbush]

This is getting silly.

A bear smashes a timber Langstroth and it can be glued together? I doubt it.

How much experience do you have with bears? Note attached pic, all boxes are salvageable. Usually the bear will bat the boxes around until the frames fall out, the poly hives can't withstand the batting.

 

[Winker]

How much experience do you have with bears?

You must have small bears in your neck of the woods. I have seen English foxes do more dammage

I bet that was a racoon You just want us to think its a bear...Only Joking

 

[Poly Hive]

My experience of bears is precisely 0 and long may it last.

You used the word smashed. That has a precise meaning.

PH

 

[Winker]

My experience of bears is precisely 0 and long may it last.

I have seen some of the local girls from Stonehaven and you're telling me you dodged them all with 0 experience? You must have lived a sheltered youth

 

[Poly Hive]

I wasn't brought up in Stoney... moral never assume...LOL

PH

 

[plumberman]

Bear with me on this one.....

I'm going to try and overwinter some nuclei on poly- but also want to trial some full size hives next year. Any recommendations for National polys? - I see paynes are going to be selling one but no details on cost yet.

 

[Poly Hive]

Try Jones for the Swienty one. Proper density and no design issues. I have some 25 nucs of theirs (Swienty) and some 15 full hives plus more than a few extra brood boxes, so am voting with my wallet.

Obviously there are now others but this is the Rolls Royce as far as I am concerned. Though thankfully not at a RR rice.

PH

 

[user 6228]

you can repair,glue foam polystyrene with epoxy adhesives,

 

[user 6228]

continuing for for a thermal conductance of 0.4w/c/m2.
with expanded foams with conductivity of about 0.03w/c/m2 we therefore need walls 75mm thick, to get the bees to be able to warm up the whole hive at -10C . Thinner walls might still allow the bees to heat up the top half. And internal silvering of the hive will also help. But as regards your orignal question, its liitle difficult without wattage and conductance per bee. As regards heating the honey, that depends on the heat losses from your hypothetical tank

note poyurethane foams are better than polystryene 0.021 has been cited for urethane. wood comes in at 0.12~0.14

Would a bee be better in a hive that has the same thermal properties of the 12" diameter hole in a 3ft diameter old tree trunk(approx 0.4w /c/m2) ? or in one that imitates the worst features of 1960's council developments.
(5w/c/m2)
This means in a standard uninsulated wooden hive if the outside temperature goes more than 4 degrees Centigrade below the bees desired temperature they have to cluster because they cannot maintain the temperature in the hive. In the British climate that could mean a significant proportion of the year.